CN106546477B - Test specimen component and test method for the test of fragile material type III Dynamic Fracture Toughness - Google Patents
Test specimen component and test method for the test of fragile material type III Dynamic Fracture Toughness Download PDFInfo
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- CN106546477B CN106546477B CN201610875683.4A CN201610875683A CN106546477B CN 106546477 B CN106546477 B CN 106546477B CN 201610875683 A CN201610875683 A CN 201610875683A CN 106546477 B CN106546477 B CN 106546477B
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- 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
- G01N3/02—Details
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- 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
- G01N3/30—Investigating strength properties of solid materials by application of mechanical stress by applying a single impulsive force, e.g. by falling weight
- G01N3/307—Investigating strength properties of solid materials by application of mechanical stress by applying a single impulsive force, e.g. by falling weight generated by a compressed or tensile-stressed spring; generated by pneumatic or hydraulic means
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- 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
- G01N2203/027—Specimens with holes or notches
Abstract
The invention discloses the test specimen component tested for fragile material type III Dynamic Fracture Toughness and test methods, test specimen component includes the test specimen ontology with grooving and the pressure head for compressing test specimen ontology, test specimen ontology is square plane plate, grooving disposed thereon is the identical grooving of four shapes, it is located at two line of symmetry positions of test specimen ontology plate face on four sides of test specimen ontology, along the direction in test specimen body thickness direction and line of symmetry, grooving, which is open, extends through the plate face up and down of test specimen ontology towards test specimen body interior in the direction of grooving；Pressure head is that four shapes are identical, arc end face pressure head with test specimen entity plate plane at point contact, and two pressure heads are symmetrically positioned on the same diagonal line of test specimen ontology side plate face, and another two pressure head is symmetrically positioned on another diagonal line of another lateral plates of test specimen ontology.The test method is tested using above-mentioned test specimen component cooperation Hopkinson pressure bar test device.
Description
Technical field
The invention belongs to material mechanical performance testing fields, in particular to are used for fragile material type III Dynamic Fracture Toughness
The test specimen component and test method of test.
Background technique
The engineering fields such as building, water conservancy, machinery, traffic, petroleum, mining industry, aerospace be directed to concrete, rock,
The breakage problem of the fragile materials such as ceramics or graphite.Fracture toughness resists the mechanics ginseng of fracture as material is characterized in fracture mechanics
Number all has important value in engineer application and theoretical research.According to the difference of cracks in body load mode, can will break
It splits and is divided into three kinds of I type, II type and type III basic models, correspondingly, it is tough that fracture toughness is also classified into I type, II type and type III fracture
Degree, i.e. KIc, KIIcAnd KIIIc.The fracture of I type refers to that opening mode is broken, i.e., two crack surfaces mutually open；The fracture of II type refers in face
Shearing-type fracture, i.e., two crack surfaces can produce relative sliding, and glide direction is vertical with crack front line direction；Type III mould
Formula refers to that shear outside the plane type (also known as tearing mode) is broken, and the opposite glide direction of two crack surfaces and crack front line direction are flat
Row.
In recent years, many researchers have carried out numerous studies, but existing most of researchs to the fracture toughness testing of material
The I type or II type fracture toughness testing being directed under the conditions of semi-static load, for the research phase of type III fracture toughness testing
To less, especially for type III fracture toughness testing research dynamic, under the conditions of high loading rate almost without, this be because
For：In laboratory, I type is applied to test specimen containing crackle and II type load is easier, and applied type III load and generally require
Sufficiently complex device and very cumbersome operation, and be used for type III Dynamic Fracture Toughness test experimental provision almost without.
However, in practical projects, type III fracture toughness is usually that engineering design, security evaluation and numerical simulation are indispensable
Basic material parameter, and under the dynamic fracture behaviors of material and the dynamic loadings such as energy dissipation rule and explosion, shock, earthquake
The dynamic characteristics and failure mechanism of engineering material have close ties, and the dynamic mechanical test of material is paid more and more attention.
Therefore, it is necessary to develop simple and feasible method to obtain fragile material type III Dynamic Fracture Toughness.
CN103471935A discloses the test specimen for testing III type fracture toughness of plastic material, and the test specimen is flat for rectangle
Plate test specimen, long side > broadside > thickness are symmetrical arranged two perpendicular to the initial of long side in the middle position of two long sides of plate
Symmetrical V-type side grooving, the test specimen is arranged in two surfaces of grooving crackle, ligament that is remaining after grooving, playing connection function
Static test can be completed on general universal testing machine.But if the test specimen is directly applied into fragile material III type dynamic
Following deficiency will be present in fracture toughness testing：(1) test specimen needs to make shallower V-type grooving, and the production of this V-type grooving is got up
It is extremely not easy, especially for coarse grained concrete and rock material, is easy to cause additional damage to test specimen, influences test specimen
Precision；It (2) when being tested using the test specimen is loaded by 4 angle points of the support base fulcrum to rectangle test specimen, load side
Formula is point loading, and loading position is exactly in rectangle test specimen angle point, this loading method implements very difficult, is especially existed
In dynamic test, easily causes load angle point to be destroyed earlier than crack tip, experiment is caused to be failed, the test specimen is dynamic in type III
Practicability in state fracture toughness testing is very poor；(3) how to calculate the fracture of III dynamic type after the invention and undeclared experiment tough
Degree, thus and it is incomplete.
Summary of the invention
For existing type III Dynamic Fracture Toughness test test specimen, structure is complicated, manufacture difficulty is big, in type III Dynamic Fracture
The practicability is poor in toughness test, and without the state of the art of feasible type III Dynamic Fracture Toughness test method, the present invention
It is intended to provide the test specimen component and test method for the test of fragile material type III Dynamic Fracture Toughness, to simplify fragile material
Type III Dynamic Fracture Toughness tests the structure of test specimen, fills up fragile material type III Dynamic Fracture Toughness test neck in the prior art
The blank in domain.
Provided by the present invention for the test specimen component of fragile material type III Dynamic Fracture Toughness test, including with grooving
Test specimen ontology and the pressure head for compressing test specimen ontology, the test specimen ontology are square plane plate, and grooving disposed thereon is four
The identical grooving of a shape, is located at two line of symmetry positions of test specimen ontology plate face on four sides of test specimen ontology, cuts
The direction of slot extends through examination towards test specimen body interior along the direction in test specimen body thickness direction and line of symmetry, grooving opening
The plate face up and down of part ontology；The pressure head is that four shapes are identical, presses with test specimen entity plate plane at the arc end face of point contact
Head, two pressure heads are symmetrically positioned on the same diagonal line of test specimen ontology side plate face, and it is another that another two pressure head is symmetrically positioned in test specimen ontology
On another diagonal line of side plate face, contact point the hanging down to its immediate this body side surface of test specimen of each pressure head and test specimen ontology
Directly it is equidistant.
In the technical solution of above-mentioned test specimen component, the pressure head is flat hemisphere or flat semiellipsoid structure pressure
Head；The pressure head is adhered in test specimen ontology plate face in its planar base surface mode parallel with test specimen ontology plate face.
In the technical solution of above-mentioned test specimen component, the contact point to its this side of immediate test specimen of pressure head and test specimen ontology
The vertical range in face is 5~10mm.
In the technical solution of above-mentioned test specimen component, the ratio between side length of the thickness of test specimen ontology and test specimen ontology for 0.1~
0.2。
In the technical solution of above-mentioned test specimen component, the ratio between depth and the side length of test specimen ontology of grooving are 0.2~0.3.
In the technical solution of above-mentioned test specimen component, the width of grooving is no more than 1mm.
In the technical solution of above-mentioned test specimen component, the side length of test specimen ontology is 50~100mm.
The present invention also provides the method for using above-mentioned test specimen module testing fragile material type III Dynamic Fracture Toughness, packets
Include following steps：
1. test specimen is mounted between the incident bar and transmission bar of Hopkinson pressure bar test device, make the rear end of incident bar
Face, transmission bar front end face respectively be located at pressure head of the test specimen ontology or more in two plate faces and contact, surveyed using Hopkinson pressure bar
The impact bar that trial assembly is set hits the front end face of incident bar, and stress wave is set the waveform shaping on incident bar front end face
It is acted on test specimen after piece shaping operation by incident bar, stress wave undergoes reflection and transmission on test specimen, is being entered using setting
Penetrate incident strain, reflection strain of the foil gauge acquisition on bar and transmission bar since hitting to test specimen ontology failure whole process
And transmission strain；
2. load is calculated by formula (I) to change with time value P (t),
In formula (I), E and A are respectively the elasticity modulus and cross-sectional area of incident bar, transmission bar, εi(t)、εr(t) it is respectively
The incidence and reflection that foil gauge on incident bar measures strain the value that changes with time, εt(t) it is surveyed for the foil gauge on transmission bar
The transmission obtained strains the value that changes with time；
Right back-pushed-type (II) calculates III type stress strength factor KⅢThe value that changes with time KⅢ(t), according to KⅢ(t) before peak
The slope of straightway determines dynamically load rateKⅢ(t) maximum value is fragile material in dynamically load rateWhen
Type III Dynamic Fracture Toughness KⅢc,
In formula (II), B and L are respectively the thickness and side length of test specimen ontology, and Y is test specimen ontology geometric shape coefficient.
In the technical solution of the method for above-mentioned testing brittle material type III Dynamic Fracture Toughness, the test specimen ontology geometry
The factors such as the size of form factor Y value and the setting position of the depth of grooving, the side length of test specimen ontology and pressure head are related, test specimen
Ontology geometric shape coefficient Y value is calculated using finite element numerical software.
The method for calculating Y value using finite element numerical software is as follows：
In the finite element numericals software for calculation such as engineering circles common ANSYS or ABAQUS, establish with test specimen ontology at appoint
The finite element numerical model of the test specimen ontology of one ratio, in the finite element numerical model of test specimen ontology with test specimen ontology load(ing) point
Apply Arbitrary Load P at corresponding position, is then answered using the type III that finite element numerical software for calculation calculates output crack tip
Power intensity factor KIII, Y value is calculated by formula (III),
In formula (III), B ' and L ' is the geometric parameter of the finite element numerical model of test specimen ontology, with B and L in test specimen ontology
Physical significance it is identical, and between these corresponding geometric parameters be in same ratio.
In the technical solution of the method for above-mentioned testing brittle material type III Dynamic Fracture Toughness, the failure of test specimen ontology refers to
Test specimen is destroyed loses bearing capacity completely.
In the technical solution of the method for above-mentioned testing brittle material type III Dynamic Fracture Toughness, by changing impact bar
The fragile material type III Dynamic Fracture Toughness under the conditions of the high loading rate of wide scope can be obtained in stroke speed.
Implement the Hopkinson pressure bar test device of the method for above-mentioned testing brittle material type III Dynamic Fracture Toughness, it is main
It to include impact bar emitter, impact bar, gas chamber, the waveform shaping piece being arranged on incident bar front end face, incident bar, transmission
Bar, the foil gauge being attached on incident bar and transmission bar, data acquisition processing system and absorbing rod, the impact bar are located at gas chamber
In, it is corresponding with the rear end of gas chamber that impact bar emitter is located at gas chamber front end, the front end of incident bar, the rear end of incident bar and transmission
The front end of bar is oppositely arranged the clamping pair to form clamping test pieces, and the foil gauge for being attached to incident bar and transmission bar surface is adopted with data
Collect processing system connection, the rear end of transmission bar and the front end of absorbing rod are oppositely arranged.
In above-mentioned Hopkinson pressure bar test device, incident bar and transmission bar are steel solid hopkinson bar, incident bar and transmission bar
Bar diameter it is equal, waveform shaping piece is the copper circular gasket that 20~50mm of diameter, thickness are about 3mm.
Compared with prior art, the invention has the advantages that：
1. the present invention provides a kind of new structural test specimen groups for the test of fragile material type III Dynamic Fracture Toughness
Part, the test specimen are made of the square-shaped planar plate test specimen ontology with straight side grooving with the pressure head for compressing test specimen ontology, test specimen
Ontology is obtained after simply cutting by block fragile material, and it is the production for completing the test specimen that seaming chuck is bonded on test specimen ontology,
Cutting processing amount is small, and straight side grooving can effectively reduce difficulty of processing, especially for coarse grained rock and concrete etc.
Material, moreover it is possible to reduce test specimen damage when processing, improve machining accuracy, with the existing rectangular flat plate test specimen with V-type grooving
It compares, not only production method is simple, difficulty of processing is low for test specimen of the present invention, and can improve the machining accuracy of test specimen.
2. the test specimen of the present invention for the test of fragile material type III Dynamic Fracture Toughness is by pressure head in test specimen ontology
On ingenious arrangement, cooperation the common Hopkinson pressure bar device of dynamic experiment can by pressure head realize to crackle dynamic
, type III loads under the conditions of high loading rate, in addition on loading position and test specimen ontology the form of grooving and position setting rationally,
Test failure will not be caused because load(ing) point cracks prior to Near A Crack Tip when load, be surveyed with existing type III Dynamic Fracture Toughness
Part of having a try is compared, it is not necessary that the load of type III dynamic loads can be realized with the use of complicated load and clamping device, moreover it is possible to
Complicated load operation is avoided, test specimen of the present invention is simple, easy to operate with loading method and is conducive to improve loading accuracy
Advantage, compensate for the existing type III fracture toughness testing test specimen deficiency that the practicability is poor in type III fracture toughness testing.
3. the present invention also provides the method using above-mentioned test specimen testing brittle material type III Dynamic Fracture Toughness, the party
Load, and the party can be realized using the test specimen provided by the invention cooperation common Hopkinson pressure bar device of dynamic experiment in method
The operating process of method and the equal very simple of calculating process of fragile material type III Dynamic Fracture Toughness, therefore this method is in test specimen
It is all had great advantages in production, device requirement, test process and input, this method has filled up brittleness in the prior art
The blank of material type III Dynamic Fracture Toughness testing field lacks, and helps to solve in engineering to feasible type III Dynamic Fracture
The actual demand of toughness test method, it is practical, be conducive to promote and apply.
4. the method for testing brittle material type III Dynamic Fracture Toughness of the present invention is easy to operate, during test
It need to only be recorded by the data acquisition processing system of Hopkinson pressure bar device since hitting to test specimen failure whole process
Incidence strain, reflection strain and transmission strain, can calculate fragile material type III Dynamic Fracture Toughness and corresponding dynamic
The type III dynamic under the conditions of the high loading rate of wide scope can be obtained in LOADING RATES, also, the stroke speed by changing impact bar
Fracture toughness has advantage applied widely.
Detailed description of the invention
Fig. 1 is the schematic perspective view that this sends out test specimen component described；
Fig. 2 is the top view of Fig. 1；
Fig. 3 is the side view of Fig. 1；
Fig. 4 is scheme of installation of the test specimen component of the present invention in Hopkinson pressure bar test device；
In figure, 1-test specimen ontology, 2-groovings, 3-pressure heads, 4-impact bars, 5-impact bar emitters, 6-gas chambers,
7-waveform shaping pieces, 8-incident bars, 9-transmission bars, 10-foil gauges, 11-data acquisition processing systems, 12-absorbing rods,
L-test specimen ontology side length, B-test specimen ontology thickness, a-grooving depth, t-grooving width, S-pressure head and test specimen
Vertical range of the contact point of ontology to its immediate this body side surface of test specimen, D-hemisphere pressure head diameter.
Specific embodiment
It is tested by the following examples and in conjunction with attached drawing to of the present invention for fragile material type III Dynamic Fracture Toughness
Test specimen component and test method be described further.It is necessary to it is pointed out here that, the following examples are only intended to preferably explain
The working principle of the invention and its practical application are stated, in order to which the present invention is used for each of its field by the technical staff in other fields
In kind facility, and improved according to the imagination of various special-purposes.Although the present invention, which has passed through text, discloses its first choice implementation
Scheme, but can be appreciated that optimization property and alterability therein by reading these technology explanatory notes, and without departing from this
It is improved in the scope and spirit of invention, but such improvement should still fall within the protection scope of the claims in the present invention.
Embodiment 1
In the present embodiment, the structural schematic diagram of the test specimen component for the test of fragile material type III Dynamic Fracture Toughness is such as
Shown in Fig. 1~3, the test specimen ontology of the test specimen component, which is cut by concrete block through diamond slice machine-cut, to be made.
For the test specimen component of fragile material type III Dynamic Fracture Toughness test, by the test specimen ontology 1 with grooving 2 and support
The pressure head 3 of test specimen ontology is pressed to form, the test specimen ontology is square plane plate, side length L=70mm, the test specimen of test specimen ontology
The thickness B=10mm of ontology, the grooving 2 on the test specimen ontology is the identical grooving of four shapes, is located at test specimen sheet
The two line of symmetry positions of four sides of body, direction of the direction of grooving along test specimen body thickness direction and line of symmetry, grooving
Opening extends through the plate face up and down of test specimen ontology towards test specimen body interior, the width of the depth a=14mm of grooving, grooving
T=1mm；The pressure head 3 is the flat hemisphere of steel that four diameter D are 10mm, the upper face of each pressure head and test specimen ontology
Or lower face, at point contact, two pressure heads are symmetrically positioned on the same diagonal line of test specimen ontology side plate face, and another two pressure head is symmetrical
On another diagonal line of another lateral plates of test specimen ontology, i.e., two diagonal lines where four pressure heads are mutually perpendicular to, each pressure head
Vertical range S with contact point to its immediate this body side surface of test specimen of test specimen ontology is 5mm.
Embodiment 2
In the present embodiment, the structural schematic diagram of the test specimen component for the test of fragile material type III Dynamic Fracture Toughness is such as
Shown in Fig. 1~3, the test specimen ontology of the test specimen component, which is cut by concrete block through diamond slice machine-cut, to be made.
For the test specimen component of fragile material type III Dynamic Fracture Toughness test, by the test specimen ontology 1 with grooving 2 and support
The pressure head 3 of test specimen ontology is pressed to form, the test specimen ontology is square plane plate, the side length L=100mm of test specimen ontology, examination
The thickness B=20mm of part ontology, the grooving 2 on the test specimen ontology is the identical grooving of four shapes, is located at test specimen
The two line of symmetry positions of four sides of ontology, the direction of grooving are cut along the direction in test specimen body thickness direction and line of symmetry
Channel opening extends through the plate face up and down of test specimen ontology towards test specimen body interior, the width of the depth a=30mm of grooving, grooving
Spend t=1mm；The pressure head 3 is the flat hemisphere of steel that four diameter D are 15mm, the upper plate of each pressure head and test specimen ontology
Face or lower face are at point contact, and two pressure heads are symmetrically positioned on the same diagonal line of test specimen ontology side plate face, another two pressure head pair
Claim to be located on another diagonal line of another lateral plates of test specimen ontology, i.e., two diagonal lines where four pressure heads are mutually perpendicular to, each to press
The vertical range S of head and contact point to its immediate this body side surface of test specimen of test specimen ontology is 10mm.
Embodiment 3
In the present embodiment, the structural schematic diagram of the test specimen component for the test of fragile material type III Dynamic Fracture Toughness is such as
Shown in Fig. 1~3, the test specimen ontology of the test specimen component, which is cut by rock block through diamond slice machine-cut, to be made.
For the test specimen component of fragile material type III Dynamic Fracture Toughness test, by the test specimen ontology 1 with grooving 2 and support
The pressure head 3 of test specimen ontology is pressed to form, the test specimen ontology is square plane plate, side length L=50mm, the test specimen of test specimen ontology
The thickness B=5mm of ontology, the grooving 2 on the test specimen ontology is the identical grooving of four shapes, is located at test specimen ontology
Two line of symmetry positions of four sides, along the direction in test specimen body thickness direction and line of symmetry, grooving is opened in the direction of grooving
Mouth extends through the plate face up and down of test specimen ontology towards test specimen body interior, the width t of the depth a=10mm of grooving, grooving
=0.8mm；The pressure head 3 is the flat hemisphere of steel that four diameter D are 8mm, the upper face of each pressure head and test specimen ontology
Or lower face, at point contact, two pressure heads are symmetrically positioned on the same diagonal line of test specimen ontology side plate face, and another two pressure head is symmetrical
On another diagonal line of another lateral plates of test specimen ontology, i.e., two diagonal lines where four pressure heads are mutually perpendicular to, each pressure head
Vertical range S with contact point to its immediate this body side surface of test specimen of test specimen ontology is 5mm.
Embodiment 4
In the present embodiment, brittleness material is tested using the cooperation Hopkinson pressure bar test device of test specimen component described in embodiment 1
Expect type III Dynamic Fracture Toughness.
Hopkinson pressure bar test device mainly includes impact bar emitter 5, impact bar 4, gas chamber 6, is arranged in incidence
Waveform shaping piece 7, incident bar 8, transmission bar 9, the foil gauge 10 being attached on incident bar and transmission bar, data on bar front end face
Acquisition processing system 11 and absorbing rod 12, the impact bar 4 are located in gas chamber 6, impact bar emitter 5 be located at gas chamber front end,
The front end of incident bar 8 and the rear end of gas chamber are corresponding, and the rear end of incident bar 8 and the front end of transmission bar 9 are oppositely arranged to form clamping examination
The clamping pair of part component 1 and 3 is attached to the foil gauge 10 and data acquisition processing system 11 of section surface in incident bar and transmission bar
Connection, the rear end of transmission bar 9 and the front end of absorbing rod 12 are oppositely arranged, and the incident bar 8 and transmission bar 9 are bar diameter 100mm
Steel solid hopkinson bar, waveform shaping piece 7 is the copper circular gasket of diameter 30mm, thickness 3mm.
The test process of fragile material type III Dynamic Fracture Toughness is as follows：
1. test specimen component is mounted between the incident bar 8 of Hopkinson pressure bar test device and transmission bar 9, make incident bar
Rear end face, transmission bar front end face respectively be located at pressure head 3 of the test specimen ontology or more in two plate faces and contact, starting impact bar hair
The trigger mechanism of injection device 5 hits impact bar 4 to the front end face of incident bar, and stress wave is set in incident bar front end face
On waveform shaping piece shaping operation after acted on test specimen by incident bar, stress wave undergone on test specimen multiple reflections and thoroughly
Both ends after penetrating eventually in test specimen reach dynamic equilibrium, using the foil gauge acquisition being arranged on incident bar and transmission bar from hitting
It hits and starts to strain and be transmitted at data acquisition to the incident strain, reflection strain and transmission of test specimen ontology failure whole process
In reason system 11.
2. load is calculated by formula (I) to change with time value P (t),
In formula (I), E and A are respectively the elasticity modulus and cross-sectional area of incident bar, transmission bar, εi(t)、εr(t) it is respectively
The incidence and reflection that foil gauge on incident bar measures strain the value that changes with time, εt(t) it is surveyed for the foil gauge on transmission bar
The transmission obtained strains the value that changes with time；
The ε 1. recorded according to incident bar, the elasticity modulus of transmission bar and cross-sectional area and stepi(t)、εr(t)、εt
(t) P (t) can be calculated in value.
After calculating P (t), III type stress strength factor K is calculated by formula (II)ⅢThe value that changes with time KⅢ(t), according to
KⅢ(t) slope of straightway determines dynamically load rate before peakKⅢ(t) maximum value is that fragile material adds in dynamic
Load rateWhen type III Dynamic Fracture Toughness KⅢc,
In formula (II), B and L are respectively the thickness and side length of test specimen ontology, and Y is test specimen ontology geometric shape coefficient, Y value benefit
It is calculated with finite element numerical software.
The method for calculating Y value using finite element numerical software is as follows：
In the finite element numericals software for calculation such as engineering circles common ANSYS or ABAQUS, establish with test specimen ontology at appoint
The finite element numerical model of the test specimen ontology of one ratio, in the finite element numerical model of test specimen ontology with test specimen ontology load(ing) point
Apply Arbitrary Load P at corresponding position, is then answered using the type III that finite element numerical software for calculation calculates output crack tip
Power intensity factor KIII, Y value is calculated by formula (III),
In formula (III), B ' and L ' is the geometric parameter of the finite element numerical model of test specimen ontology, with B and L in test specimen ontology
Physical significance it is identical, and between these corresponding geometric parameters be in same ratio.
For the present embodiment, determining Y value is 3.088 according to the method described above.
B, L and Y value and P (t), which are substituted into formula (II), can be calculated III type stress strength factor KⅢChange at any time
Change value KⅢ(t), according to KⅢ(t) slope of straightway can determine dynamically load rate before peakThen K is soughtⅢ(t)
Maximum value is up to fragile material in dynamically load rateWhen type III Dynamic Fracture Toughness KⅢc。
Claims (10)
1. a kind of test specimen component for the test of fragile material type III Dynamic Fracture Toughness, it is characterised in that including band grooving (2)
Test specimen ontology (1) and compress the pressure head (3) of test specimen ontology, the test specimen ontology is square plane plate, disposed thereon
Grooving (2) is the identical grooving of four shapes, is located at two line of symmetries of test specimen ontology plate face on four sides of test specimen ontology
Position, along the direction in test specimen body thickness direction and line of symmetry, grooving is open towards test specimen body interior in the direction of grooving
Extend through the plate face up and down of test specimen ontology；The pressure head (3) is that four shapes are identical, connect with test specimen ontology plate face at point
The arc end face pressure head of touching, two pressure heads are symmetrically positioned on the same diagonal line of test specimen ontology side plate face, the symmetrical position of another two pressure head
In on another diagonal line of another lateral plates of test specimen ontology, the contact point of each pressure head and test specimen ontology to its immediate test specimen sheet
The vertical range of body side surface is equal.
2. the test specimen component according to claim 1 for the test of fragile material type III Dynamic Fracture Toughness, feature exist
In the pressure head be flat hemisphere or flat semiellipsoid structure pressure head.
3. the test specimen component according to claim 2 for the test of fragile material type III Dynamic Fracture Toughness, feature exist
It is adhered in test specimen ontology plate face in the pressure head in its planar base surface mode parallel with test specimen ontology plate face.
4. the test specimen component according to claim 1 or 2 or 3 for the test of fragile material type III Dynamic Fracture Toughness,
Be characterized in that the contact point of pressure head and test specimen ontology to the vertical range (S) of its immediate this body side surface of test specimen be 5~10mm.
5. the test specimen component according to claim 1 or 2 or 3 for the test of fragile material type III Dynamic Fracture Toughness,
It is characterized in that the ratio between the thickness (B) of test specimen ontology and the side length (L) of test specimen ontology are 0.1~0.2.
6. the test specimen component according to claim 1 or 2 or 3 for the test of fragile material type III Dynamic Fracture Toughness,
It is characterized in that the ratio between the depth (a) of grooving and the side length (L) of test specimen ontology are 0.2~0.3.
7. the test specimen component according to claim 6 for the test of fragile material type III Dynamic Fracture Toughness, feature exist
It is no more than 1mm in the width (t) of grooving.
8. the test specimen component according to claim 1 or 2 or 3 for the test of fragile material type III Dynamic Fracture Toughness,
The side length (L) for being characterized in that test specimen ontology is 50~100mm.
9. using the method for test specimen module testing fragile material type III Dynamic Fracture Toughness described in one of claim 1 to 8,
It is characterized in that including the following steps：
1. test specimen component is mounted between the incident bar (8) of Hopkinson pressure bar test device and transmission bar (9), make incident bar
Rear end face, transmission bar front end face respectively be located at pressure head (3) of the test specimen ontology or more in two plate faces and contact, utilize Hope golden
The impact bar (4) of gloomy compression bar test device hits the front end face of incident bar, and stress wave is set in incident bar front end face
On waveform shaping piece shaping operation after acted on test specimen component by incident bar, stress wave undergoes reflection on test specimen component
And transmission, using the foil gauge acquisition being arranged on incident bar and transmission bar to test specimen ontology failure whole process since hitting
Incident strain, reflection strain and transmission strain；
2. load is calculated by formula (I) to change with time value P (t),
In formula (I), E and A are respectively the elasticity modulus and cross-sectional area of incident bar, transmission bar, εi(t)、εrIt (t) is respectively incidence
The incidence and reflection that foil gauge on bar measures strain the value that changes with time, εt(t) it is measured for the foil gauge on transmission bar
Transmission strains the value that changes with time；
Right back-pushed-type (II) calculates III type stress strength factor KⅢThe value that changes with time KⅢ(t), according to KⅢ(t) straight line before peak
The slope of section determines dynamically load rateKⅢ(t) maximum value is fragile material in dynamically load rateWhen
Type III Dynamic Fracture Toughness KⅢc,
In formula (II), B and L are respectively the thickness and side length of test specimen ontology, and Y is test specimen ontology geometric shape coefficient.
10. the method for testing brittle material type III Dynamic Fracture Toughness according to claim 9, it is characterised in that described
Test specimen ontology geometric shape coefficient Y value is calculated using finite element numerical software.
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| CN106932253B (en) * | 2017-04-17 | 2019-08-30 | 四川大学 | Test the test specimen component and test method of rock I-II mixed mode dynamic fracture toughness |
| CN107367431A (en) * | 2017-08-30 | 2017-11-21 | 中国科学院武汉岩土力学研究所 | A kind of stress wave transflector experimental system based on plane fluctuation |
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