CN114720284A - HDPE material performance hydraulic bulging test method and system - Google Patents
HDPE material performance hydraulic bulging test method and system Download PDFInfo
- Publication number
- CN114720284A CN114720284A CN202111599619.5A CN202111599619A CN114720284A CN 114720284 A CN114720284 A CN 114720284A CN 202111599619 A CN202111599619 A CN 202111599619A CN 114720284 A CN114720284 A CN 114720284A
- Authority
- CN
- China
- Prior art keywords
- data
- bulging
- test
- test piece
- tensile
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000000463 material Substances 0.000 title claims abstract description 78
- 229920001903 high density polyethylene Polymers 0.000 title claims abstract description 68
- 239000004700 high-density polyethylene Substances 0.000 title claims abstract description 68
- 238000010998 test method Methods 0.000 title claims description 13
- 238000012360 testing method Methods 0.000 claims abstract description 175
- 238000004088 simulation Methods 0.000 claims abstract description 67
- 238000000034 method Methods 0.000 claims abstract description 50
- 238000002474 experimental method Methods 0.000 claims abstract description 42
- 238000009864 tensile test Methods 0.000 claims abstract description 33
- 230000008569 process Effects 0.000 claims abstract description 30
- 238000004458 analytical method Methods 0.000 claims abstract description 21
- 230000004044 response Effects 0.000 claims abstract description 13
- 230000006378 damage Effects 0.000 claims description 50
- 238000006073 displacement reaction Methods 0.000 claims description 48
- 229920003023 plastic Polymers 0.000 claims description 23
- 239000004033 plastic Substances 0.000 claims description 23
- 230000009467 reduction Effects 0.000 claims description 22
- 230000007246 mechanism Effects 0.000 claims description 13
- 230000010354 integration Effects 0.000 claims description 12
- 230000008859 change Effects 0.000 claims description 10
- 238000009826 distribution Methods 0.000 claims description 9
- 239000007769 metal material Substances 0.000 claims description 9
- 230000002829 reductive effect Effects 0.000 claims description 9
- 238000003825 pressing Methods 0.000 claims description 8
- 230000035882 stress Effects 0.000 description 37
- 239000000835 fiber Substances 0.000 description 7
- 230000009471 action Effects 0.000 description 6
- 229910000831 Steel Inorganic materials 0.000 description 5
- 230000015556 catabolic process Effects 0.000 description 5
- 238000011161 development Methods 0.000 description 5
- 230000018109 developmental process Effects 0.000 description 5
- 229920000642 polymer Polymers 0.000 description 5
- 239000010959 steel Substances 0.000 description 5
- 238000004364 calculation method Methods 0.000 description 4
- 210000004027 cell Anatomy 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000011160 research Methods 0.000 description 4
- 238000005452 bending Methods 0.000 description 3
- 238000006731 degradation reaction Methods 0.000 description 3
- 230000005489 elastic deformation Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000000977 initiatory effect Effects 0.000 description 3
- 239000004698 Polyethylene Substances 0.000 description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000013467 fragmentation Methods 0.000 description 2
- 238000006062 fragmentation reaction Methods 0.000 description 2
- 238000001746 injection moulding Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 230000036961 partial effect Effects 0.000 description 2
- -1 polyethylene Polymers 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000010008 shearing Methods 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000012935 Averaging Methods 0.000 description 1
- 208000027418 Wounds and injury Diseases 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000009795 derivation Methods 0.000 description 1
- 238000001212 derivatisation Methods 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- 239000003651 drinking water Substances 0.000 description 1
- 235000020188 drinking water Nutrition 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000013013 elastic material Substances 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 208000014674 injury Diseases 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000007620 mathematical function Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 210000001724 microfibril Anatomy 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 239000010956 nickel silver Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000031877 prophase Effects 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 230000003938 response to stress Effects 0.000 description 1
- 230000011218 segmentation Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 230000002459 sustained effect Effects 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
- G01N3/10—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by pneumatic or hydraulic pressure
- G01N3/12—Pressure testing
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/28—Investigating ductility, e.g. suitability of sheet metal for deep-drawing or spinning
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/44—Resins; Plastics; Rubber; Leather
- G01N33/442—Resins; Plastics
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0016—Tensile or compressive
- G01N2203/0017—Tensile
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/003—Generation of the force
- G01N2203/0042—Pneumatic or hydraulic means
- G01N2203/0048—Hydraulic means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
- G01N2203/0075—Strain-stress relations or elastic constants
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/0202—Control of the test
- G01N2203/0212—Theories, calculations
- G01N2203/0218—Calculations based on experimental data
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/026—Specifications of the specimen
- G01N2203/0262—Shape of the specimen
- G01N2203/0278—Thin specimens
- G01N2203/0282—Two dimensional, e.g. tapes, webs, sheets, strips, disks or membranes
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/026—Specifications of the specimen
- G01N2203/0298—Manufacturing or preparing specimens
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Engineering & Computer Science (AREA)
- Food Science & Technology (AREA)
- Medicinal Chemistry (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention discloses a method and a system for testing HDPE material performance hydraulic bulging, wherein the method comprises the following steps: respectively adopting a uniaxial tension test and a hydraulic bulging test to test the material performance of the test piece to obtain tension test data and bulging test data; performing finite element simulation according to the tensile test data and the bulging test data respectively to obtain simulated tensile data and simulated bulging data; and comparing the simulated tensile data with the tensile experimental data, and comparing the simulated bulging data with the bulging experimental data to obtain the mechanical response relation of the test piece. The invention provides a comparison of a finite element method for a hydraulic bulging experiment, so that the hydraulic bulging experiment can explain the phenomenon of the experiment process from the angle of numerical analysis, and the accuracy of the analysis of the mechanical properties of the HDPE material is further improved.
Description
Technical Field
The invention relates to the technical field of bulging experiment tests, in particular to a method and a system for testing the performance hydraulic bulging of an HDPE material.
Background
The high polymer polyethylene (HDPE) material is widely applied to the aspects of residential drinking water delivery, domestic water discharge, municipal water underground delivery, natural gas delivery, telecommunication, partial heat supply pipelines, solid-liquid medium transmission of medical systems and the like.
Compared with the traditional metal material, the HDPE material has many advantages and becomes the best choice for urban pipe networks. However, the development and application level of HDPE pipes in China is generally low, and the HDPE pipes have certain gap compared with the advanced level in China, and how to correctly evaluate the mechanical property and the destructive behavior of the HDPE pipes in order to really use the HDPE pipes in large area in China is the primary problem to be faced. HDPE pipe is a typical plastic pipe and the most predominant form of loading is internal pressure. Therefore, the research on the internal pressure load bearing capacity of the HDPE pipe is an important basis for correctly recognizing and using the HDPE pipe, and is also one of important means for evaluating the raw material of the pipe.
Under the action of internal pressure load, three failure modes of the HDPE pipe mainly exist. The first is ductile failure, where the HDPE pipe begins to creep and expand under the action of high internal pressure, and when sustained until a certain point suddenly bulges at the weakest part of the pipe and fails very quickly. The second is brittle fracture, and the small cracks in the pipe under the action of small internal pressure generate crack propagation at the crack tip under the action of tearing stress to cause the damage of the pipe. The crack propagation speed is usually quite slow, requiring more than decades, and is therefore also referred to as the slow crack stage; it is also possible that a fairly rapid crack propagation results in an instantaneous crack, i.e. a rapid crack propagation in general, and the incidence of rapid crack propagation is now greatly suppressed, so stress cracking in general is referred to as slow crack growth. Third, degradation of the HDPE pipe monolith leads to brittle failure, a stage that has been well in excess of 50 years.
For HDPE pipe, either toughness failure or slow crack propagation is intrinsically yield-induced, with the only difference being the yield mechanism. The yield mechanism is mainly divided into two types: shear yield and crazing shear yield are shear deformations of a material due to molecular slip during deformation. Ductile failure is a typical shear yield process, and is the stress to which an HDPE pipe is subjected under internal pressure reaches or exceeds the yield stress of the material, so that the HDPE pipe is damaged soon after shear yield. The slow crack propagation is generally considered to be caused by that impurities are mixed in the HDPE material or defects or cavities are generated in the processing process, so that stress concentration is generated at the positions of the defects when the pipe is subjected to external force, when the concentrated stress exceeds the yield stress of the HDPE, silver cracks are generated on the part of the material, fibers in the silver cracks generate creep fracture to generate cracks along with the increase of time under the action of the external force, and new silver cracks are formed at new crack tips, so that the process recurs and leads the cracks to propagate forwards, namely the slow crack propagation is generally called. Crack propagation will be accompanied by a breakdown of the internal fiber structure, the breakdown of the fibers within the crazes determining the rate of crack propagation. Generally, it is thought that the molecular chains in or among fibers are disentangled to cause fiber breakage, the number of polymer-linked molecules is used for predicting the service life of the HDPE pipe, and with the progress of the material synthesis technology, the novel pipe often has very excellent slow crack propagation resistance, the toughness damage area becomes wider and wider, and the damage time can reach decades. Therefore, it is important to study the ductile fracture of the steel.
For HDPE pipes, mechanical property analysis is usually performed by using conventional tensile, bending, impact, hardness and hydraulic bulge tests. The small punch test is an experimental method which uses a punch to punch a test piece sheet at a certain speed, records load-displacement (or deformation deflection) data of the test piece in the whole process from deformation to failure, and analyzes the data to obtain various performance parameters of the material. However, because the test piece is subjected to concentrated load, the relation between the material performance and the force-displacement curve is difficult to establish theoretically; the evaluation on yield strength, tensile strength, fracture toughness and the like mostly belongs to empirical correlation, and empirical correlation formulas obtained by different researchers are different; meanwhile, the empirical correlation formulas are greatly influenced by factors such as the size of the steel ball, the rigidity of the steel ball, the centering of the steel ball, the friction coefficient between the steel ball and the test piece and the like. Compared with a small punch rod technology, the hydraulic bulging technology has the advantages that the test piece is subjected to uniform load and is convenient for theoretical analysis and is not influenced by factors such as eccentricity and friction. The hydraulic bulging test has higher precision and is not limited by excessive test conditions. However, the finite element simulation study of the experimental process is clearly insufficient, and the phenomena of the experimental process, such as local thinning and toughness damage, cannot be explained from the point of view of numerical analysis.
Disclosure of Invention
The invention aims to provide a method and a system for testing HDPE material performance hydraulic bulging, and aims to solve the problems that finite element simulation research in the existing hydraulic bulging experiment process is insufficient, and the phenomenon of the experiment process cannot be explained from the angle of numerical analysis.
In order to achieve the aim, the invention provides a HDPE material performance hydraulic bulging test method, which comprises the following steps:
respectively testing the material performance of the test piece by adopting a uniaxial tension test and a hydraulic bulging test to obtain tension experiment data and bulging experiment data;
carrying out finite element simulation according to the tensile test data and the bulging test data respectively to obtain simulated tensile data and simulated bulging data;
and comparing the simulated tensile data with the tensile experimental data, and comparing the simulated bulging data with the bulging experimental data to obtain the mechanical response relation of the test piece.
Optionally, the material performance of the test piece is tested by using a uniaxial tensile test to obtain tensile test data, and the method specifically comprises the following steps:
determining an engineering stress-strain curve according to the characteristics of the test piece;
carrying out uniaxial tension on the test piece, and recording the real stress strain;
when the volume is not changed in the stretching process, the real stress strain meets the formula:
εT＝ln(1+ε)
σT＝σ(1+ε)
wherein ε is the engineering strain εTFor true strain, σ and σTRespectively representing engineering stress and real stress;
and selecting a Poisson's ratio, and adding the Poisson's ratio into the real stress-strain satisfying formula to obtain a real stress-strain curve.
Optionally, before the material performance of the test piece is tested by using the uniaxial tensile test and tensile test data is obtained, the method further includes:
determining a hyperelastic model of the test piece as a Marlow structure to represent the nonlinear elasticity of the test piece;
using isotropic power law hardening
Determining a plastic model of the test piece;
selecting a reduced criterion ductile damage initial criterion to judge the damage evolution rule.
Optionally, the performing finite element simulation according to the tensile test data to obtain simulated tensile data specifically includes:
establishing a stretching finite element model for the uniaxial stretching test piece;
adopting a three-dimensional eight-node reduction integral unit to perform meshing on the stretching finite element model;
and adopting a display format integral ABAQUS/Explicit, setting a density and a total mass scaling value, controlling the loading displacement and the loading rate to be consistent with those in a uniaxial tension test, and carrying out a simulation experiment to obtain simulated tension data, wherein the simulated tension data comprises a load-displacement curve, equivalent strain cloud pictures at different loading displacements, a failure mechanism, a failure position and port morphology.
Optionally, the material performance of the test piece is tested by adopting a hydraulic bulging test, so as to obtain bulging test data, which specifically includes:
and carrying out a bulging test on the test piece by adopting a hydraulic bulging test device to obtain bulging displacement data and test piece strain stress data.
Optionally, performing finite element simulation according to the bulging experimental data to obtain simulated bulging data specifically includes:
establishing a hydraulic bulging finite element model according to a hydraulic bulging experimental device;
carrying out mesh division on the hydraulic bulging finite element model by adopting a three-dimensional eight-node reduction integral unit;
a first-order reduction integration unit is provided with an hourglass control rigidity parameter to obtain a refined grid;
adopting a display format integral ABAQUS/Explimit, setting a total mass scaling value, setting a fixture as a metal material, setting an elastic modulus, a Poisson ratio and a density value, and describing by using an isotropic linear elastic constitutive structure;
setting the bottom end of the fixture as a fixed end, constraining all degrees of freedom, and simultaneously applying symmetric constraints in X and Y directions to two symmetric planes respectively; setting friction contact on the upper and lower surfaces of the test piece, and setting a friction coefficient; and applying pressure on the lower surface of the test piece at a constant speed according to the experimental pressure in a pressure loading mode to obtain simulated bulging data, wherein the simulated bulging data comprises a deformation strain cloud chart, a pressure-displacement curve, a damage distribution cloud chart and local thinning data.
Optionally, the comparing the simulated tensile data with the tensile experimental data to obtain a mechanical response relationship of the test piece specifically includes:
analyzing the deformation rule of the test piece under tension according to the load-displacement curve and equivalent strain cloud charts at different loading displacements;
determining the necking change of the test piece according to the failure mechanism and the failure position;
and determining the evolution rule of the test piece from stretching to breaking according to the necking change and the port morphology.
Optionally, comparing the simulated ballooning data with the ballooning experiment data to obtain a mechanical response relationship of the test piece specifically includes:
analyzing the bulging deformation rule of the test piece according to a pressure-displacement curve obtained by deformation strain cloud pictures, simulation and experiments;
predicting the fracture position of the test piece according to the damage distribution cloud picture;
and analyzing the test piece thinning rule according to the local thinning data.
A HDPE material performance hydraulic bulge test system, the system comprising:
the test unit is used for testing the material performance of the test piece by respectively adopting a uniaxial tensile test and a hydraulic bulging test to obtain tensile test data and bulging test data;
the simulation unit is used for carrying out finite element simulation according to the tensile test data and the bulging test data respectively to obtain simulated tensile data and simulated bulging data;
and the analysis unit is used for comparing the simulated tensile data with the tensile experimental data and comparing the simulated bulging data with the bulging experimental data to obtain a mechanical response relation of the test piece.
Optionally, the simulation unit includes a stretching simulation module and a bulging simulation module;
the stretch simulation module is configured to:
establishing a stretching finite element model for the uniaxial stretching test piece;
carrying out mesh division on the stretching finite element model by adopting a three-dimensional eight-node reduction integral unit;
adopting a display format integral ABAQUS/Explicit, setting a density and a total mass scaling value, controlling a loading displacement and a loading rate to be consistent with those in a uniaxial tension test, and carrying out a simulation experiment to obtain simulation tension data, wherein the simulation tension data comprises a load-displacement curve, equivalent strain cloud pictures at different loading displacements, a failure mechanism, a failure position and port morphology;
the ballooning simulation module is to:
establishing a hydraulic bulging finite element model according to a hydraulic bulging experimental device;
carrying out mesh division on the hydraulic bulging finite element model by adopting a three-dimensional eight-node reduction integral unit;
a first-order reduction integration unit is provided with an hourglass control rigidity parameter to obtain a refined grid;
adopting a display format integral ABAQUS/Explimit, setting a total mass scaling value, setting a fixture as a metal material, setting an elastic modulus, a Poisson ratio and a density value, and describing by using an isotropic linear elastic constitutive structure;
setting the bottom end of the fixture as a fixed end, constraining all degrees of freedom, and simultaneously applying symmetric constraints in X and Y directions to two symmetric planes respectively; setting friction contact on the upper and lower surfaces of a test piece, and setting a friction coefficient; and applying pressure on the lower surface of the test piece at a constant speed according to the experimental pressure in a pressure loading mode to obtain simulated bulging data, wherein the simulated bulging data comprises a deformation strain cloud chart, a pressure-displacement curve, a damage distribution cloud chart and local thinning data.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
compared with the existing model, the HDPE material performance hydraulic bulging test method and system provided by the invention embody different mechanical properties and have less uncertain parameters, and the related mechanical properties of the HDEP material can be reflected more intuitively. In addition, the invention analyzes the nonlinear elasticity of the HDPE material, improves the accuracy of mechanical property analysis, and overcomes the problem of inaccuracy caused by analyzing the linear elasticity of most existing models.
The invention also provides a technical basis for predicting the damage of the HDEP material by effectively analyzing and describing the toughness damage of the HDEP material.
The invention provides a comparison of a finite element method for a hydraulic bulging experiment, so that the hydraulic bulging experiment can explain phenomena in the experiment process from the angle of numerical analysis, such as local thinning and toughness damage, and the accuracy of HDPE material mechanical property analysis is further improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a schematic drawing of the dimensions of a shaft tensile test piece;
FIG. 2 is a graph of engineering stress strain relationship for HDPE;
FIG. 3 is a graph of true stress strain for HDPE;
FIG. 4 is a schematic diagram of strain decomposition;
FIG. 5 is a tensile finite element model of a uniaxial tensile test piece;
FIG. 6 is a graph comparing experimental and simulated load-displacement curves;
FIG. 7 is a cloud graph of equivalent strain at a loading displacement of 31mm in a simulation;
FIG. 8 is a schematic view of a uniaxial tensile damage derivatization process
FIG. 9 is a comparative graph of fractures after stretching; wherein a is a finite element fracture, and b is an experimental fracture;
FIG. 10 is a schematic flow chart of the hydraulic bulge test device;
FIG. 11 is a bulging finite element model of a hydraulic bulging experiment;
FIG. 12 is a strain cloud under 8 MPa;
FIG. 13 is a graph comparing experimental and simulated pressure-displacement curves; a is a finite element simulation diagram, and b is an experimental result diagram;
FIG. 14 is a cloud of damage distributions before the balloon test piece breaks;
FIG. 15 is a schematic view of partial thinning;
FIG. 16 is a graph showing the variation of the reduced thickness with load.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
The invention aims to perform uniaxial tension experiments and hydraulic bulging experiments on HDPE, and perform finite element modeling and numerical simulation on the experimental process. By reasonably selecting a description method of constitutive relation and failure mode of the HDPE material, mechanical response of a test piece in an experimental process is analyzed, and physical characteristics such as local thinning are discussed so as to deeply know failure mode of HDPE.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
The HDPE material performance hydraulic bulging test method provided by the embodiment comprises the following steps:
respectively testing the material performance of the test piece by adopting a uniaxial tension test and a hydraulic bulging test to obtain tension experiment data and bulging experiment data;
performing finite element simulation according to the tensile test data and the bulging test data respectively to obtain simulated tensile data and simulated bulging data;
and comparing the simulated tensile data with the tensile experimental data, and comparing the simulated bulging data with the bulging experimental data to obtain the mechanical response relation of the test piece.
Each step is described in detail below with reference to examples.
Firstly, testing the material performance of a test piece by adopting a uniaxial tensile test to obtain tensile test data
1.1 test piece and experimental equipment
The test pieces in the embodiment are PE80 grade M7600 raw materials produced by Chinese petrochemical Yanshan petrochemical industry, the sheet test pieces are all prepared by adopting a single-screw injection molding process, and the injection molding temperature is 165 ℃. The dimensions of the uniaxial tensile test piece are shown in FIG. 1.
Selecting the standard ASTM D638-10 with wider allowable range of the thickness of the test piece as the reference standard of the HDPE material mechanical tensile experiment.
A GWT4503 universal testing machine provided by SANS is adopted in the stretching experiment, and a DBX-800 large-deformation extensometer is adopted as an extensometer to ensure the experiment precision. The experimental reference standard is ASTM D638, and the experimental temperature is controlled to be 25 +/-3 ℃ during the stretching process. Parallel test pieces 3. Displacement loading is adopted in the experiment, and the loading rate is controlled to be 2 mm/min.
1.2 engineering stress-strain relationship
The engineering stress-strain relationship of the HDPE material used in this example is closer to the mechanical response of the metal material, as shown in fig. 2. When subjected to uniaxial tension, the stress-strain curve experiences:
elastic deformation of the AB section: in the region before the yield point is reached, the stress increases with increasing strain and the change in the stress-strain curve deviates from a straight trend. The salient feature of this region is that its deformation will recover slowly as the external force is removed.
Elastic-plastic deformation of the BC section: yielding at point B reaches the maximum of the engineering stress-strain curve, creating plastic deformation, strain softening at segment BC creates necking, with increasing strain and decreasing stress, during which the polymer interior undergoes very complex changes: the spherulite structure is transformed into a fiber structure, and finally molecular chains are pulled off and broken.
As can be seen from FIG. 2, the stress-strain curve of polyethylene can be approximately regarded as linear relationship only in a small range, and the overall behavior is nonlinear relationship. In the initial deformation stage, the stress increases along with the increase of deformation, meanwhile, the nonlinear relation of stress and strain is more obvious, and the material is softened and falls after yielding until finally breaking.
1.3 true stress-strain relationship
The engineering stress-strain curve is based on the assumption that the cross-sectional area and the specimen length do not change during the drawing process. In the actual stretching process, the section of the stretching test piece is continuously slightly reduced, and the strain of HDPE is relatively large compared with the strain of common metal materials, so that the true stress-strain condition needs to be considered.
If the volume does not change in the stretching process, the true stress strain satisfies the following conditions:
εT＝ln(1+ε)
σT＝σ(1+ε)
wherein ε is the engineering strain εTFor true strain, σ and σTRepresenting engineering stress and true stress, respectively.
The bulk of HDPE test pieces in actual tensile deformation is variable and therefore the poisson's ratio needs to be taken into account, which is typically 0.38 for polymeric materials. Figure 3 shows the true stress-strain curve for HDPE.
Second, HDPE material constitutive model
2.1 super elastic model
The material constitutive model describes the stress response of a material under a given strain by a mathematical function. The Marlow method can accurately describe the elastic behavior of the material before the strain reaches 0.6, so that the Marlow structure is selected in the embodiment to characterize the nonlinear elasticity of the HDPE material.
In addition to the non-linear elastic characteristic, after the strain reaches 0.2, the local plastic deformation occurs to cause the tensile test piece to have obvious necking phenomenon, thereby leading to the reduction of the bearing area and the stress. This mechanism causes an error between the Marlow constitutive and the experimental curve at the later stage of loading, indicating that the influence of plasticity cannot be ignored.
2.2 Plastic model
In experimental data, the strain provided includes not only the plastic strain of the material, but also the overall strain of the material. The overall strain must be decomposed into elastic and plastic strain components.
ε＝εe+εp
Wherein epsilonpIs the true plastic strain, ε is the overall true strain, εeIs the true elastic strain. For a linear elastic material, the elastic strain is equal to the ratio of the true stress to the young's modulus. In this example, Marlow's structure was chosen to describe the non-linear elastic behavior in the early stages of deformationThe change in elastic modulus is large, while the elastic modulus after the material yields can be considered to be substantially constant, i.e., linear elasticity. Thus, the plastic strain can be calculated from the following formula:
εp＝ε-εe＝ε-εy-Δσ/E
wherein epsilonyThe total strain before yielding, E is the tangent modulus at the yield point, and Δ σ ═ σ - σyIs true stress and yield stress sigmayThe difference of (a). The schematic diagram is shown in fig. 4.
In an embodiment, isotropic power law hardening is used
A plastic strain curve, i.e. a plastic model, is described, with the parameters listed in table 1.
TABLE 1 Plastic model fitting parameters
2.3 ductile Damage model
In this embodiment, a reduced criterion is selected to determine the beginning of the damage for predicting the damage caused by the development of the hole. The model assumes that the equivalent plastic strain at the onset of damage is a function of the three axes of stress and the strain rate:
wherein eta is-p/q stress triaxial degree, p is compressive stress, q is a Misses equivalent stress,
is the equivalent plastic strain rate. The injury initiation criterion is met when the following conditions are met:
wherein wDIs a state variable that monotonically increases with plastic deformation. Once the set starting criteria are met, the material stiffness will degrade according to the damage evolution law specified by the criteria.
The damage evolution law describes the rate of degradation of material stiffness, ABAQUS assumes that the stiffness degradation associated with active failure mechanisms can be modeled using a scalar damage variable D. At any given time in the analysis process, the stress tensor in the material is given by the scalar damage equation:
wherein
Is the effective (or undamaged) stress tensor computed in the current increment.
Refers to the stress present in the material without damage. When D ═ 1, the material loses load bearing capacity. By default, any element may be deleted from the model if all nodes of that element lose their bearer capabilities. This example uses the energy criterion provided by ABAQUS for damage derivation definition, and simulates fragmentation by giving the energy required for failure after damage initiation (fragmentation energy).
Thirdly, carrying out finite element simulation according to the tensile experiment data to obtain simulated tensile data
3.1 tensile finite element model
The finite element model of the uniaxial tensile test piece is shown in fig. 5, the distance between the clamps in the actual experiment is 92.46mm, and the tensile finite element model intercepts the test piece in order to keep the loading condition consistent with the experiment. The model includes all parallel segments and a small portion of the transitional arc region.
Considering that the test piece is subjected to bending load in the subsequent simulation of the bulging experiment, in order to avoid the possible shearing self-locking phenomenon and keep the same in the two calculation examples, the three-dimensional eight-node reduction integration unit (C3D8R) is used for carrying out meshing on the model. The linear reduction integration unit is equivalent to a normal stress unit because only one integration point is arranged at the center of the unit, the result on the integration point is relatively accurate, but the node stress obtained through interpolation and averaging is not accurate enough. The stress concentration problem of a single node is not involved in the present embodiment, and therefore cell selection is considered feasible.
3.2 loads and boundary conditions
This example uses a Explicit format integral ABAQUS/Explicit with a density set at 0.9Kg/mm3 and a total mass scaling of 10. The loading speed is kept consistent with that in the experiment by adopting a loading mode of controlling displacement and is 2.00 mm/min. The left end of the test piece is a fixed end, all degrees of freedom are restrained, a clamping state is simulated, and loading is applied to the right end face.
3.3 analysis of simulation results and Experimental results
3.3.1 deformation analysis
FIG. 6 shows the load displacement curves of HDPE test pieces from uniaxial tensile tests and finite element simulations. The HDPE breaking process can be seen in three parts: a large elastic deformation zone, an elastic-plastic deformation zone and a failure zone. The mechanical model chosen can accurately describe the mechanical behavior of the material in the elastic and initial plastic zones, but the development of the damage is faster in the later stages, resulting in a fracture that occurs earlier than in the experiment. The simulated displacement at break was 31.15mm, while the experimental value was 33.78mm with an error of 7.78%.
Fig. 7 shows the equivalent strain cloud at a loading displacement of 31mm in the simulation. It can be seen that the test piece is approximately uniformly deformed in the early stage of stretching, and as the loading displacement increases, the deformation gradually concentrates on a small area on the right side, which is also the starting position of aging.
3.3.2 necking analysis
The initiation of cracks requires considerable fracture energy due to the presence of interfacial adhesion and occurs at higher stresses, as can be seen from the damage evolution process that increases the yield fracture process. Once a void is formed, its growth depends on the stability of the filament elongation and the resistance of the particle-matrix interface. The ductile damage criterion used herein is based on the creation, growth, and aggregation of pores in the material, and the above damage process can be best described as shown in fig. 8.
Fig. 8 shows that the tensile specimen failure occurs first at the center position, and when the damage of the center cell reaches the threshold value of 1, the damage of the adjacent cells is only 0.16. And the displacement load at the starting moment of the central unit failure is smaller than that at the rest positions. For the whole, the toughness damage of the HDPE material reaches the initial criterion at the tensile displacement of 15mm, namely w in the formula 12D1. Thereafter, the evolution phase of the damage was entered and finally fractured at a loading displacement of 30mm, during which the amount of damage D developed exponentially as a result of the rapid accumulation of fracture energy at a later stage.
3.3.3 fracture morphology comparison
Fig. 9 shows fracture shape comparison of finite element simulation result (a) and experiment result (b). The experimental results show a clear polymer fracture characteristic, i.e. a long chain deformation process is firstly undergone, then crazing occurs, and microfibril fracture is shown at the fracture. In finite elements, fracture fibers correspond to significant deformation of the elements at the end of loading. When the necking position is locally failed, the accumulated damage of individual units reaches a critical value, a preset unit deleting mechanism is triggered, the stress at the fracture is released by deleting part of units, and the rest units are rapidly elongated, so that the appearance characteristic of fig. 9(a) is presented.
Fourthly, testing the material performance of the test piece by adopting a hydraulic bulging test to obtain bulging test data
4.1 Hydraulic bulge experimental device
The test is carried out by a self-made hydraulic bulging device, the size of the test piece is a wafer test piece with the diameter of 10mm, and the pressing speed is 0.2 MPa/min. As shown in fig. 10, the hydraulic inflation device mainly includes a high-pressure pump, a pressure gauge, a pressure sensor, a displacement conduction device, a data acquisition card, a computer and the like, and the experimental process is as shown in fig. 10. The pressure gauge and the pressure sensor are arranged on the oil circuit, the pressure gauge is mainly used for facilitating experimenters to observe the implementation condition of pressure, and pressure signals are transmitted to the computer through the data acquisition card by the pressure sensor. And the displacement generated by the deformation of the central point of the test piece is transmitted to the displacement sensor by the displacement transmission device and then passes through the data acquisition card.
Fifthly, carrying out finite element simulation according to the bulging experiment data to obtain simulated bulging data
5.1 bulging finite element model
The finite element model of the hydraulic bulge test is shown in fig. 11, and the thickness of the test piece is 1mm, which is consistent with the test. The bulging experiment model is an obvious axisymmetric model, and after the calculation speed of numerical simulation and the precision of a result are considered at the same time, the whole test piece is subjected to segmentation treatment in the research, and the 1/4 model is taken for operation.
Considering that the test piece is subjected to bending load during loading, a three-dimensional eight-node reduction integration unit (C3D8R) is also used for meshing the model so as to avoid the shearing self-locking phenomenon. The concept of hourglass stiffness is introduced into a first-order reduction integration unit in ABAQUS, and the calculation accuracy of the reduction integration unit can be effectively improved by reasonably refining the grid. It is recommended that there be at least four layers of cells in the thickness direction, so for this embodiment, five layers of divisions are made in the thickness direction of the test piece to control the calculation error.
5.2 loads and boundary conditions
Also using Explicit format integration ABAQUS/Explicit, the total mass scales to 10. The fixture is made of metal material, and has elastic modulus of 200Gpa, Poisson ratio of 0.3 and density of 7.9Kg/mm 3. Since the fixture is much stiffer than the rubber material, it is described using an isotropic linear spring constitutive.
The loading is consistent with the experiment, and the pressure is applied to the lower surface of the test piece at a constant speed according to 0.2Mpa/min in a pressure loading mode. In consideration of freedom degree control, the bottom end of the fixture is set to be a fixed end, all freedom degrees are restrained, and meanwhile symmetrical restraint in the X direction and the Y direction is respectively applied to two symmetrical planes.
The friction properties between the specimen and the fixture are also an important influencing factor. In practical experiments, the pressing ring has a pressing load, so that the HDPE sheets and the fixture can be considered to have larger static friction. In the simulation, frictional contact was set on the upper and lower surfaces of the test piece, respectively, and the friction coefficient was set to 0.5.
5.3 analysis of simulation results and Experimental results
5.3.1 deformation analysis
As shown in fig. 12, it is evident that there are two main areas of deformation, one at the bottom end of the specimen, which are subjected to tensile forces, and plastic flow occurs gradually. The other position is the specimen tip.
Fig. 13 shows the pressure-displacement curve of the HDPE test piece obtained by finite element simulation and the corresponding experimental results. The test has higher pre-loading (4-6MPa), so the early results cannot be analyzed, but the change trends of the two before the failure of the test piece are completely the same, including the change rate dP/dU of the pressure along with the displacement, are subjected to the processes of ascending-descending-ascending-descending.
5.3.2 Damage analysis
As shown in fig. 14, the damage distribution cloud before the rupture of the ballooning test piece is shown, and the position where the damage value is the largest is the test piece vertex and is expanded in a ring shape. Large deformation regions were observed in the experiment compared to other locations. In addition, the contact position of the clamping ring has certain damage development, which needs to be taken into consideration to prevent non-top end fracture in the experiment.
The results show that in the simulation of the bulging experiment, the toughness damage method can also predict the fracture position of the test piece more accurately. However, considering the mechanical complexity of HDPE materials, small changes in loading rate, temperature, etc. may result in changes in damage behavior, and therefore, a great deal of work is required to determine the model parameters in the early stage.
5.3.3 local thinning analysis
In addition, significant local thinning of the HDPE specimen tips was observed during the experiments, as indicated by the tip thickness H1 being less than the side thickness H2, as shown in fig. 15. This phenomenon is effectively characterized in finite element simulation. By defining H1 and H2 as the thickness of the specimen at positions 0mm and 2mm from the center point when unloaded, and defining DH (H2-H1) as the reduced thickness, the variation law of the reduced thickness with load shown in fig. 16 can be obtained from the simulation results of the finite elements. The result shows that DH and applied pressure present obvious nonlinear relation, the HDPE sheet is in the elastic deformation stage in the loading prophase, at this moment, the thinning is less, it is nearly uniform bulging to explain the test piece. In contrast, the reduced thickness exhibited a significant upward trend after the pressure reached 2MPa, which was a result of plastic flow of the material under loading. Furthermore, the relationship of pressure to reduced thickness can be well fitted using a third order polynomial.
Sixth, summarize
In this embodiment, a constitutive model of the HDPE material is revised through a uniaxial tensile test, a plurality of superelasticity mechanical models and damage models are considered, a finite element simulation analysis is performed on a tensile test and a hydraulic bulging test, and the obtained conclusion is as follows:
the superelasticity constitutive relation can effectively describe the nonlinear elastic behavior of the HDPE material, wherein the Marlow constitutive relation shows better fitting accuracy. Numerical simulations of the HDPE elastic phase can be achieved in the commercial software ABAQUS by means of parameter calibration.
At a loading rate of 2mm/min, the HDPE material shows significant elasto-plastic mechanical behavior, including physical phenomena such as necking. The contribution of plastic deformation must therefore be taken into account when considering the mechanical description of HDPE, and the purely elastic constitutive cannot be used simply.
Fracture of HDPE materials is caused by a ductile failure mechanism, microscopically, by the action of voids formed by the separation of the crystallite boundaries and by the tensile extension of the polymer chains. This process can be characterized using a product criteria failure model.
The unit types are reasonably selected and combined with the constitutive relation, so that the numerical value reduction can be accurately carried out on the uniaxial stretching process. The research discusses the damage development and necking phenomenon of the simulation result, and the fracture morphology obtained by simulation and experiment is basically consistent.
The finite element simulation of the hydraulic bulging experiment accurately predicts the deformation process and the failure occurrence position of the test piece.
The obvious local thinning phenomenon appears in the bulging experiment simulation, the thinning speed is low in the early stage of loading, the thinning thickness obviously rises after the external pressure reaches 2MPa, and the relation can be described by using a third-order polynomial.
The invention also provides a system corresponding to the method, and the HDPE material performance hydraulic bulging test system comprises:
the test unit is used for testing the material performance of the test piece by respectively adopting a uniaxial tensile test and a hydraulic bulging test to obtain tensile test data and bulging test data;
the simulation unit is used for carrying out finite element simulation according to the tensile test data and the bulging test data respectively to obtain simulated tensile data and simulated bulging data;
and the analysis unit is used for comparing the simulated tensile data with the tensile experimental data and comparing the simulated bulging data with the bulging experimental data to obtain a mechanical response relation of the test piece.
Wherein the simulation unit comprises a stretching simulation module and an inflation simulation module;
the stretch simulation module is configured to:
establishing a stretching finite element model for the uniaxial stretching test piece;
carrying out mesh division on the stretching finite element model by adopting a three-dimensional eight-node reduction integral unit;
adopting a display format integral ABAQUS/Explicit, setting a density and a total mass scaling value, controlling a loading displacement and a loading rate to be consistent with those in a uniaxial tension test, and carrying out a simulation experiment to obtain simulation tension data, wherein the simulation tension data comprises a load-displacement curve, equivalent strain cloud pictures at different loading displacements, a failure mechanism, a failure position and port morphology;
the ballooning simulation module is to:
establishing a hydraulic bulging finite element model according to a hydraulic bulging experimental device;
carrying out mesh division on the hydraulic bulging finite element model by adopting a three-dimensional eight-node reduction integral unit;
a first-order reduction integration unit is provided with an hourglass control rigidity parameter to obtain a refined grid;
adopting a display format integral ABAQUS/Explimit, setting a total mass scaling value, setting a fixture as a metal material, setting an elastic modulus, a Poisson ratio and a density value, and describing by using an isotropic linear elastic constitutive structure;
setting the bottom end of the fixture as a fixed end, constraining all degrees of freedom, and simultaneously applying symmetric constraints in X and Y directions to two symmetric planes respectively; setting friction contact on the upper and lower surfaces of a test piece, and setting a friction coefficient; and applying pressure on the lower surface of the test piece at a constant speed according to the experimental pressure in a pressure loading mode to obtain simulated bulging data, wherein the simulated bulging data comprises a deformation strain cloud chart, a pressure-displacement curve, a damage distribution cloud chart and local thinning data.
For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (10)
1. A HDPE material performance hydraulic bulging test method is characterized by comprising the following steps:
respectively adopting a uniaxial tension test and a hydraulic bulging test to test the material performance of the test piece to obtain tension test data and bulging test data;
carrying out finite element simulation according to the tensile test data and the bulging test data respectively to obtain simulated tensile data and simulated bulging data;
and comparing the simulated tensile data with the tensile experimental data, and comparing the simulated bulging data with the bulging experimental data to obtain the mechanical response relation of the test piece.
2. The HDPE material performance hydraulic bulging test method of claim 1, wherein the uniaxial tensile test is used for testing the material performance of the test piece to obtain tensile test data, and the method specifically comprises the following steps:
determining an engineering stress-strain curve according to the characteristics of the test piece;
carrying out uniaxial tension on the test piece, and recording the real stress strain;
when the volume is not changed in the stretching process, the real stress strain meets the formula:
εT＝ln(1+ε)
σT＝σ(1+ε)
wherein ε is the engineering strain εTFor true strain, σ and σTRespectively representing engineering stress and real stress;
and selecting a Poisson ratio, and adding the Poisson ratio into the real stress-strain satisfying formula to obtain a real stress-strain curve.
3. The HDPE material performance hydraulic bulging test method as claimed in claim 1, wherein before the test piece material performance using uniaxial tensile test is tested to obtain tensile test data, the method further comprises:
determining a hyperelastic model of the test piece as a Marlow structure to represent the nonlinear elasticity of the test piece;
using isotropic power law hardening
Determining a plastic model of the test piece;
selecting a reduced criterion ductile damage initial criterion to judge the damage evolution rule.
4. The HDPE material performance hydraulic bulging test method of claim 1, wherein the finite element simulation is performed according to the tensile test data to obtain simulated tensile data, and the method specifically comprises the following steps:
establishing a stretching finite element model for the uniaxial stretching test piece;
carrying out mesh division on the stretching finite element model by adopting a three-dimensional eight-node reduction integral unit;
and adopting a display format integral ABAQUS/Explicit, setting a density and a total mass scaling value, controlling the loading displacement and the loading rate to be consistent with those in a uniaxial tension test, and carrying out a simulation experiment to obtain simulated tension data, wherein the simulated tension data comprises a load-displacement curve, equivalent strain cloud pictures at different loading displacements, a failure mechanism, a failure position and port morphology.
5. The HDPE material performance hydraulic bulging test method of claim 1, wherein the material performance of the test piece is tested by using a hydraulic bulging test, and bulging test data are obtained, and the method specifically comprises the following steps:
and carrying out a bulging test on the test piece by adopting a hydraulic bulging test device to obtain bulging displacement data and test piece strain stress data.
6. The HDPE material performance hydraulic bulging test method of claim 1, wherein the obtaining of the simulated bulging data by performing finite element simulation according to the bulging test data specifically comprises:
establishing a hydraulic bulging finite element model according to a hydraulic bulging experimental device;
carrying out mesh division on the hydraulic bulging finite element model by adopting a three-dimensional eight-node reduction integral unit;
setting an hourglass control rigidity parameter in a first-order reduction integral unit to obtain a refined grid;
adopting a display format integral ABAQUS/Explimit, setting a total mass scaling value, setting a fixture as a metal material, setting an elastic modulus, a Poisson ratio and a density value, and describing by using an isotropic linear elastic constitutive structure;
setting the bottom end of the fixture as a fixed end, constraining all degrees of freedom, and simultaneously applying symmetric constraints in X and Y directions to two symmetric planes respectively; setting friction contact on the upper and lower surfaces of the test piece, and setting a friction coefficient; and applying pressure on the lower surface of the test piece at a constant speed according to the experimental pressure in a pressure loading mode to obtain simulated bulging data, wherein the simulated bulging data comprises a deformation strain cloud chart, a pressure-displacement curve, a damage distribution cloud chart and local thinning data.
7. The HDPE material performance hydraulic bulging test method of claim 1, wherein the simulated tensile data is compared with the tensile experimental data to obtain a mechanical response relation of a test piece, and the method specifically comprises the following steps:
analyzing the deformation rule of the test piece under tension according to the load-displacement curve and equivalent strain cloud charts at different loading displacements;
determining the necking change of the test piece according to the failure mechanism and the failure position;
and determining the evolution rule of the test piece from stretching to breaking according to the necking change and the port morphology.
8. The HDPE material performance hydraulic bulging test method of claim 6, wherein the step of comparing the simulated bulging data with the bulging experimental data to obtain a mechanical response relation of the test piece specifically comprises:
analyzing the bulging deformation rule of the test piece according to a pressure-displacement curve obtained by deformation strain cloud pictures, simulation and experiments;
predicting the fracture position of the test piece according to the damage distribution cloud picture;
and analyzing the test piece thinning rule according to the local thinning data.
9. A HDPE material performance hydraulic bulge test system, characterized in that the system comprises:
the test unit is used for testing the material performance of the test piece by respectively adopting a uniaxial tensile test and a hydraulic bulging test to obtain tensile test data and bulging test data;
the simulation unit is used for carrying out finite element simulation according to the tensile test data and the bulging test data respectively to obtain simulated tensile data and simulated bulging data;
and the analysis unit is used for comparing the simulated tensile data with the tensile experimental data and comparing the simulated bulging data with the bulging experimental data to obtain a mechanical response relation of the test piece.
10. The HDPE material performance hydraulic bulge test system of claim 9, wherein the simulation unit comprises a tensile simulation module and a bulge simulation module;
the stretch simulation module is configured to:
establishing a stretching finite element model for the uniaxial stretching test piece;
carrying out mesh division on the stretching finite element model by adopting a three-dimensional eight-node reduction integral unit;
adopting a display format integral ABAQUS/Explicit, setting a density and a total mass scaling value, controlling a loading displacement and a loading rate to be consistent with those in a uniaxial tension test, and carrying out a simulation experiment to obtain simulation tension data, wherein the simulation tension data comprises a load-displacement curve, equivalent strain cloud pictures at different loading displacements, a failure mechanism, a failure position and port morphology;
the ballooning simulation module is to:
establishing a hydraulic bulging finite element model according to a hydraulic bulging experimental device;
carrying out mesh division on the hydraulic bulging finite element model by adopting a three-dimensional eight-node reduction integral unit;
a first-order reduction integration unit is provided with an hourglass control rigidity parameter to obtain a refined grid;
adopting a display format integral ABAQUS/Explimit, setting a total mass scaling value, setting a fixture as a metal material, setting an elastic modulus, a Poisson ratio and a density value, and describing by using an isotropic linear elastic constitutive structure;
setting the bottom end of the fixture as a fixed end, constraining all degrees of freedom, and simultaneously applying symmetric constraints in X and Y directions to two symmetric planes respectively; setting friction contact on the upper and lower surfaces of a test piece, and setting a friction coefficient; and applying pressure on the lower surface of the test piece at a constant speed according to the experimental pressure in a pressure loading mode to obtain simulated bulging data, wherein the simulated bulging data comprises a deformation strain cloud chart, a pressure-displacement curve, a damage distribution cloud chart and local thinning data.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111599619.5A CN114720284A (en) | 2021-12-24 | 2021-12-24 | HDPE material performance hydraulic bulging test method and system |
| GB2208555.9A GB2614352B (en) | 2021-12-24 | 2022-06-10 | Hydraulic bulge testing method and system for material properties of HDPE |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111599619.5A CN114720284A (en) | 2021-12-24 | 2021-12-24 | HDPE material performance hydraulic bulging test method and system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114720284A true CN114720284A (en) | 2022-07-08 |
Family
ID=82235108
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111599619.5A Pending CN114720284A (en) | 2021-12-24 | 2021-12-24 | HDPE material performance hydraulic bulging test method and system |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN114720284A (en) |
| GB (1) | GB2614352B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2614352A (en) * | 2021-12-24 | 2023-07-05 | China Special Equipment Inspection & Res Inst | Hydraulic bulge testing method and system for material properties of HDPE |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112199879A (en) * | 2020-10-22 | 2021-01-08 | 中国石油大学(华东) | Method for establishing and analyzing three-dimensional fracture model of polyethylene under complex stress |
| CN112284921B (en) * | 2020-10-22 | 2022-12-27 | 苏州热工研究院有限公司 | Method for determining uniaxial stress-strain relation of material based on high-temperature hydraulic bulge test sample |
| CN114720284A (en) * | 2021-12-24 | 2022-07-08 | 中国特种设备检测研究院 | HDPE material performance hydraulic bulging test method and system |
| CN114626264A (en) * | 2022-03-01 | 2022-06-14 | 南京理工大学 | Free bulging-based method for measuring flow stress of thin-wall metal pipe |
-
2021
- 2021-12-24 CN CN202111599619.5A patent/CN114720284A/en active Pending
-
2022
- 2022-06-10 GB GB2208555.9A patent/GB2614352B/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2614352A (en) * | 2021-12-24 | 2023-07-05 | China Special Equipment Inspection & Res Inst | Hydraulic bulge testing method and system for material properties of HDPE |
| GB2614352B (en) * | 2021-12-24 | 2023-12-20 | China Special Equipment Inspection & Res Inst | Hydraulic bulge testing method and system for material properties of HDPE |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2614352B (en) | 2023-12-20 |
| GB2614352A (en) | 2023-07-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Zhang et al. | Tensile behavior of an auxetic structure: Analytical modeling and finite element analysis | |
| Li et al. | The initiation and growth of macroscopic martensite band in nano-grained NiTi microtube under tension | |
| CN105631148A (en) | Method for analyzing mechanical property of UD-CMC (Unidirectional Ceramic Matrix Composite) under stress oxidation environment | |
| Pan et al. | Effect of multiple secondary cracks on FRP debonding from the substrate of reinforced concrete beams | |
| CN114720284A (en) | HDPE material performance hydraulic bulging test method and system | |
| CN111339703A (en) | Virtual prediction method for material hardening behavior under large strain condition | |
| Djavanroodi et al. | Equal channel angular pressing of tubular samples | |
| Zenkert et al. | Fatigue of closed cell foams | |
| CN107657081A (en) | A kind of Forecasting Methodology of aircraft tension structure breaking load | |
| Doroszko et al. | Modeling of the tension and compression behavior of sintered 316L using micro computed tomography | |
| Kossakowski | Influence of initial porosity on strength properties of S235JR steel at low stress triaxiality | |
| Chen et al. | Uniaxial ratchetting of filled rubber: experiments and damage-coupled hyper-viscoelastic-plastic constitutive model | |
| CN111089561A (en) | Tunnel deformation early warning value determination method | |
| Zemanová et al. | Smeared fixed crack model for numerical modelling of glass fracture in LS-DYNA | |
| Yolum et al. | Peridynamic modelling of delamination in DCB specimen | |
| Qiao et al. | Tensile-mechanical degradation-properties and JC constitutive model of studs after strong-acid corrosion | |
| Sawada | Fracture criterion considering notch brittleness of polytetrafluoroethylene under quasi-static loading | |
| Kossakowski | Effect of initial porosity on material response under multi-axial stress state for S235JR steel | |
| Wang et al. | Effective strain range-based prediction and analysis of the fatigue life of pipette shaft seal ring | |
| Wang et al. | Sectional finite element analysis of coupled deformation between elastoplastic sheet metal and visco-elastoplastic body | |
| Luong et al. | Damage initiation mechanism in rubber sheet composites during the static loading | |
| Takekoshi et al. | Study of material modeling of polymers for impact analysis | |
| Cao et al. | High-temperature deformation and interfacial damage in CGI: 3D numerical analysis | |
| Esposito et al. | Multiscale material model for asr-affected concrete structures | |
| Barbier et al. | Mean stress effect by incremental two scale damage model |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |