CN106649928A - Method for analyzing influence of injection molding process on impact behavior of thin-walled large-curvature polycarbonate plastic part - Google Patents

Method for analyzing influence of injection molding process on impact behavior of thin-walled large-curvature polycarbonate plastic part Download PDF

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Publication number
CN106649928A
CN106649928A CN201610846739.3A CN201610846739A CN106649928A CN 106649928 A CN106649928 A CN 106649928A CN 201610846739 A CN201610846739 A CN 201610846739A CN 106649928 A CN106649928 A CN 106649928A
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yield stress
thin
annealing
curvature
plastic part
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许英杰
陆欢
张卫红
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Northwestern Polytechnical University
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Northwestern Polytechnical University
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]

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  • Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
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  • General Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)

Abstract

The invention discloses a method for analyzing an influence of an injection molding process on an impact behavior of a thin-walled large-curvature polycarbonate plastic part, and solves the technical problem of low practicality of an existing method for analyzing an influence on an impact behavior of a polycarbonate composite material. According to the technical scheme, the method comprises the steps of performing a tension test on an annealed sample piece, constructing a yield stress main curve, and calculating a main curve conversion factor; establishing a relationship between molding heat history and a yield stress according to a yield stress-annealing time main curve for calculating the yield stress; building a thin-walled large-curvature plastic part finite element model, judging all unit application failure criteria in the model, and obtaining impact behaviors of the thin-walled large-curvature plastic part under different heat history conditions. The yield stress main curve is established, so that a logarithmic evolution equation of the yield stress in an annealing process is constructed; and optimization is performed from the perspective of machining conditions to obtain the thin-walled large-curvature polycarbonate plastic part most suitable for use; and the whole process from modeling to calculation is concise and efficient, so that the method is high in practicality.

Description

What injection molding process affected on thin-walled deep camber Merlon plastic impact behavior divides Analysis method
Technical field
The present invention relates to the analysis method that a kind of polycarbonate composite material impact behavior affects, more particularly to a kind of injection The analysis method that moulding process affects on thin-walled deep camber Merlon plastic impact behavior.
Background technology
The transparency, high ductibility, the resistance to impact of thermoplastic polymer Merlon (Polycarbonate, abbreviation PC) Deng excellent properties so as to become one of irreplaceable new structural material of aerospace field, be widely used in Aeronautics and Astronautics The polycarbonate components of various configuration and the protective articles of astronaut etc..The resistance to impact of PC, for measurement Chalpy impact examination Test, be best in thermoplastic.Therefore so as to include airplane canopy, protective face mask, eye protection suitable for impact application Mirror, windshield, vehicle window etc..Injection mo(u)lding is for manufacturing the most widely used method of thermoplastic polymer product.Whole During, the polymer of melting is injected into die cavity, is cooled down under high stuffing pressure afterwards, injection mo(u)lding polymer machinery performance Influence factor be usually the thermal history of process.
Document " Processing-induced properties in glassy polymers:development of the yield stress in PC[J].International Polymer Processing,2005,20(2):170- 177 " analysis method that a kind of polycarbonate composite material impact behavior affects is disclosed.The method directly predicts high polymer in note The distribution of yield stress during molded, the method is to be in glassy state temperature temperature below based on PC materials in annealing process With the differentiation relation of yield stress, through the numerical simulation of injection molding process, can estimate yield stress in a product Distribution, it was demonstrated that thermal history during from melt to solidification have impact on the yield stress of PC products after shaping, but, in whole mistake Cheng Zhong, only illustrates impact of the molding technological condition to thin-walled deep camber Merlon plastic yield stress after shaping, without this Plant molding technological condition to analyze the influence research of thin-walled deep camber Merlon plastic impact behavior.
The content of the invention
In order to overcome the shortcomings of the analysis method poor practicability that existing polycarbonate composite material impact behavior affects, this It is bright that the analysis method that a kind of injection molding process affects on thin-walled deep camber Merlon plastic impact behavior is provided.The method pair Annealing exemplar carries out stretching experiment, measures the change curve of the yield stress with annealing time of exemplar under different annealing temperature, One yield stress principal curve of construction, calculates principal curve conversion factor.Shaping is set up according to yield stress-annealing time principal curve Thermal history calculates yield stress with the relation of yield stress.Thin-walled deep camber plastic FEM model is set up, then to finite element Model applies corresponding load boundary condition, and all unit application failure criterias in model are judged, show that thin-walled is big Impact behavior of the curvature plastic in the case of different thermal histories.Due to establishing a yield stress principal curve, construct The logarithm EVOLUTION EQUATION of yield stress in annealing process is succinct from the angle of processing conditions, whole injection molding process Yield stress is legibly calculated, the impact behavior of PC products is analyzed, the thin-walled deep camber that optimization obtains being best suitable for using gathers Carbonic ester plastic；Whole process from modeling to calculating is succinctly efficiently, practical.
The technical solution adopted for the present invention to solve the technical problems：A kind of injection molding process is to the poly- carbon of thin-walled deep camber The analysis method that acid esters plastic impact behavior affects, is characterized in comprising the following steps：
Step one, to annealing, exemplar carries out stretching experiment, measures the yield stress of exemplar under different annealing temperature with moving back The change curve of fiery time, constructs a yield stress principal curve, uses formula
Calculate principal curve conversion factor.
In formula, Δ UaFor experiment parameter, 205kj/mol；R is universal gas constant；T is that the heat of any annealing process is gone through History；TrefFor reference temperature.
Step 2, according to principal curve conversion factor, use formula
Calculate the accumulation equivalent time of plastic under each mold temperature in injection mo(u)lding cooling procedure.
Step 3, injection mo(u)lding are from glassy state temperature TgMold temperature is cooled to until this process that shaping terminates is regarded as Equivalent annealing process, with following formula the PC materials in cooling procedure are constrained：
T ＞ Tg：
T≤Tg：
In formula, TgFor the glass transition temperature of PC；TcT () is the thermal history of material in injection process.
Step 4, the relation that shaping thermal history and yield stress are set up according to yield stress-annealing time principal curve, with public affairs Formula
σy=σY, 0+c·log(teff+ta) (5)
Calculate yield stress.
In formula, σY, 0, c, taTo test fitting parameter；teffFor equivalent time.
Step 5, thin-walled deep camber plastic FEM model is set up, then corresponding load side is applied to FEM model All unit application failure criterias in model are judged by boundary's condition, if the strain of certain unit exceedes a certain of regulation Individual fixed value ε, then it is assumed that the unit has damaged failure.After whole element analysises judge to finish, then shock analysis terminate.Finally Draw impact behavior of the thin-walled deep camber plastic in the case of different thermal histories.
The invention has the beneficial effects as follows：The method carries out stretching experiment to exemplar of annealing, and measures sample under different annealing temperature The yield stress of part constructs a yield stress principal curve with the change curve of annealing time, calculates principal curve conversion factor. Shaping thermal history is set up according to yield stress-annealing time principal curve and calculates yield stress with the relation of yield stress.Set up thin Wall deep camber plastic FEM model, then applies corresponding load boundary condition to FEM model, to all in model Unit application failure criteria judged, draws impact behavior of the thin-walled deep camber plastic in the case of different thermal histories.Due to A yield stress principal curve is established, the logarithm EVOLUTION EQUATION of the yield stress in annealing process has been constructed, from processing bar The angle of part is set out, and yield stress is concisely calculated in whole injection molding process, analyzes the impact row of PC products For optimization obtains the thin-walled deep camber Merlon plastic for being best suitable for using；Whole process from modeling to calculating is succinctly efficient, It is practical.
The present invention is elaborated with reference to the accompanying drawings and detailed description.
Description of the drawings
Fig. 1 is the thermal history curve of PC material plastics under different mold temperatures in the inventive method.
Fig. 2 is that, as mold temperature is raised in the inventive method, experimental result is tied with the yield stress of analog result contrast Fruit is schemed.
Fig. 3 is in the inventive method under different mold temperatures, to impact the kinetic energy change curve in impact process that drops hammer.
Specific embodiment
Reference picture 1-3.What injection molding process of the present invention affected on thin-walled deep camber Merlon plastic impact behavior divides Analysis method is comprised the following steps that：
Below for mold temperature be 40 DEG C, 60 DEG C, 80 DEG C, 120 DEG C, 130 DEG C of thin-walled PC material plastics, calculate different The yield stress of thin-walled PC materials and this yield stress is applied in thin-walled model carries out shock analysis under mold temperature, and will Resulting result carries out contrast verification with actual experimental result.
Step 1：By mold temperature be 40 DEG C, 60 DEG C, 80 DEG C, 120 DEG C, the injection moulding process of 130 DEG C of thin-walled PC materials Analogue simulation, draws the thermal history of different mold temperatures.
Step 2：According to thermal history data, formula is used
Calculate yield stress-annealing time principal curve conversion factor.In formula, Δ UaFor experiment parameter, 205kj/mol；R is Universal gas constant；T is the thermal history of any annealing process；TrefFor reference temperature.
Step 3：According to principal curve conversion factor, formula is used
Calculate the accumulation equivalent time of plastic under each mold temperature in injection mo(u)lding cooling procedure.
Step 4：Injection mo(u)lding is from glassy state temperature TgMold temperature is cooled to until this process that shaping terminates is regarded as Equivalent annealing process, with following formula the PC materials in cooling procedure are constrained：
T ＞ Tg：
T≤Tg：
In formula, TgFor the glass transition temperature of PC；TcT () is the thermal history of material in injection process.
Step 5：Assume in whole injection molding process, physical evolution process and the surrender in annealing process of yield stress The evolutionary process of stress is identical, a series of experiment discussion yield stress in annealing process has been carried out in research and has been drilled Change, use following formula
σy(t)=σY, 0+c·log(teff+ta) (5)
Calculate the yield stress of thin-walled deep camber Merlon plastic.In formula, σY, 0, c, taTo test fitting parameter.
Step 6：The material properties of yield stress are added into thin-walled deep camber Merlon Plastic part model and in model All unit application maximum strain criterion of strength judge successively, if certain unit strain exceed regulation some fixed value ε, then it is assumed that the unit has damaged failure.After whole element analysises judge to finish, then shock analysis terminate.The method can divide Impact behavior of the analysis thin-walled deep camber plastic in the case of different thermal histories.Fig. 3 is that under different mold temperatures, impact is dropped hammer Kinetic energy change in impact process.It is identical with experimental result trend, it can be seen that the result obtained using present invention detection and reality Test measurement result to coincide preferably.

Claims (1)

1. a kind of analysis method that injection molding process affects on thin-walled deep camber Merlon plastic impact behavior, its feature exists In comprising the following steps：
Step one, to annealing, exemplar carries out stretching experiment, measures the yield stress of exemplar under different annealing temperature with during annealing Between change curve, construct a yield stress principal curve, use formula
a T ( T ) = exp [ ΔU a R · [ 1 T - 1 T ref ] ] - - - ( 1 )
Calculate principal curve conversion factor；
In formula, Δ UaFor experiment parameter, 205kj/mol；R is universal gas constant；T is the thermal history of any annealing process；Tref For reference temperature；
Step 2, according to principal curve conversion factor, use formula
t eff = ∫ 0 t a T - 1 ( T ( t ) ) dt - - - ( 2 )
Calculate the accumulation equivalent time of plastic under each mold temperature in injection mo(u)lding cooling procedure；
Step 3, injection mo(u)lding are from glassy state temperature TgBe cooled to mold temperature until shaping terminate this process regard as it is equivalent Annealing process, with following formula the PC materials in cooling procedure are constrained：
T > T g : t eff c = 0 - - - ( 3 )
T ≤ T g : t eff c = ∫ 0 t c a T - 1 ( T c ( t ) ) dt - - - ( 4 )
In formula, TgFor the glass transition temperature of PC；TcT () is the thermal history of material in injection process；
Step 4, the relation that shaping thermal history and yield stress are set up according to yield stress-annealing time principal curve, use formula
σy=σy.0+c·log(teff+ta) (5)
Calculate yield stress；
In formula, σY, 0, c, taTo test fitting parameter；teffFor equivalent time；
Step 5, thin-walled deep camber plastic FEM model is set up, then corresponding load boundary bar is applied to FEM model All unit application failure criterias in model are judged by part, if the strain of certain unit exceedes some of regulation and consolidates Definite value ε, then it is assumed that the unit has damaged failure；After whole element analysises judge to finish, then shock analysis terminate；Finally draw Impact behavior of the thin-walled deep camber plastic in the case of different thermal histories.
CN201610846739.3A 2016-09-23 2016-09-23 Method for analyzing influence of injection molding process on impact behavior of thin-walled large-curvature polycarbonate plastic part Pending CN106649928A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110987706A (en) * 2019-11-14 2020-04-10 合肥通用机械研究院有限公司 Method for estimating fracture toughness main curve reference temperature of ferritic steel by using impact energy

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101717565A (en) * 2009-11-20 2010-06-02 金发科技股份有限公司 High-low temperature resistant flame retardant polycarbonate composite and moulded products prepared therefrom
CN103093062A (en) * 2013-02-19 2013-05-08 西北工业大学 Parametric analysis method of effect of injection molding process to plastic part buckling deformation

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101717565A (en) * 2009-11-20 2010-06-02 金发科技股份有限公司 High-low temperature resistant flame retardant polycarbonate composite and moulded products prepared therefrom
CN103093062A (en) * 2013-02-19 2013-05-08 西北工业大学 Parametric analysis method of effect of injection molding process to plastic part buckling deformation

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
YINGJIE XU等: "Processing-Induced Inhomogeneity of Yield Stress in Polycarbonate Product and Its Influence on the Impact Behavior", 《POLYMERS 2016》 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110987706A (en) * 2019-11-14 2020-04-10 合肥通用机械研究院有限公司 Method for estimating fracture toughness main curve reference temperature of ferritic steel by using impact energy

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Application publication date: 20170510