JP2011196884A - Simulation device of creep deformation characteristic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simulation device capable of performing highly accurately simulation of a creep deformation characteristic of a resin molding component, in a mode universal to the shape or the structure of a test piece cut out from the resin molding component which is a final product using a fiber reinforced resin material or the like, without performing a lot of complicated measurement or calculation.SOLUTION: This simulation device 20 includes a determination part 20a of a modulus of longitudinal elasticity, an activation energy determination part 20b, a stress index determination part 20c, a determination part 20d of a time index and a rate constant, and a strain rate calculation part 20e. Further, a deformation characteristic measuring part 30 for measuring an elastic deformation characteristic or a creep deformation characteristic of test pieces TP, TPcut out mechanically from a fiber reinforced resin molding component 10 is connected to the simulation device 20.

Description

  The present invention relates to a creep deformation characteristic simulation apparatus, and more particularly to a creep deformation characteristic simulation apparatus for resin molded parts such as fiber reinforced resin molded parts.

  In recent years, a number of resin molded parts that are lightweight and have a high degree of freedom have been used in vehicles such as automobiles.

  Since such resin molded parts are often subjected to loads under high ambient temperatures over time, the creep deformation characteristics of resin molded parts are evaluated efficiently and accurately at the research and development stage, and the final It is required to easily determine the specifications.

  Patent Document 1 discloses a creep physical property test method that eliminates the repetition of a plurality of stress measurements for each temperature in the creep test and efficiently determines the creep physical property value. The steady creep physical property value according to the so-called Norton law. And a method for calculating a time-curable creep property value according to a so-called time-curable creep law from a load history of a stress relaxation process.

  Specifically, in Patent Document 1, a cylindrical test piece is formed in advance, and a constant load is applied to the test piece while applying a constant load (strain is constant). A stress change (load change) is measured, and a graph relating to a change in stress with respect to elapsed time is obtained. Each steady creep property value according to the Norton rule is determined by a single regression analysis, and each time-curing creep property value according to the time-curing creep rule is determined by a multiple regression analysis.

JP 2007-85778 A

  However, according to the study of the present inventor, in the configuration proposed in Patent Document 1, a cylindrical test piece is formed in advance to obtain each creep physical property value, so that it is actually formed as a final product. There is a basic problem that a creep property value reflecting the structure of a molded part cannot be obtained.

  In Patent Document 1, steady creep physical property values and time-curing creep physical property values are determined by regression analysis. Therefore, in order to improve the accuracy of the obtained creep physical property values, a large number of cylindrical test pieces are used. It is necessary to measure many profiles in the stress relaxation process after molding, and it is complicated to obtain a high-accuracy creep property value and obtain a high-accuracy creep deformation characteristic.

  In particular, when using a complex resin material, for example, a fiber reinforced resin material, a test piece molded in advance using the fiber reinforced resin material is compared with a fiber reinforced resin molded part that is actually molded as a final product. The creep property value tends to deviate from the creep property value of the fiber reinforced resin molded part as the final product. In this situation, how many test pieces are molded? Even if many stress relaxation process profiles are measured, it is difficult to obtain a highly accurate creep property value.

The present invention has been made in view of such circumstances, and the test piece cut out from a resin molded part which is a final product using a fiber reinforced resin material or the like without complicated and a large amount of measurement and calculation. It is an object of the present invention to provide a simulation apparatus capable of performing a simulation of creep deformation characteristics of a resin molded part with high accuracy in a form universal to the shape and structure.

  In order to achieve the above object, the present invention determines a corrected longitudinal elastic modulus by applying a finite element analysis (hereinafter referred to as FEA) based on the elastic deformation characteristics of a test piece cut out from a resin molded part. Based on the longitudinal elastic modulus determination part and the mathematical formula showing the creep strain rate applying the time hardening law with the activation energy, stress index, time index and rate constant as the creep physical properties based on the creep deformation characteristics of the specimen The activation energy determination unit that determines the activation energy and the mathematical formula in which the stress corrected by applying FEA using the longitudinal elastic modulus based on the creep deformation characteristics is substituted, The stress index determination unit for determining the stress index and the time corrected together by applying FEA based on the creep deformation characteristics A strain that calculates a creep strain rate by substituting the activation energy, the stress index, the time index, and the rate constant into the equation A first characteristic is that the apparatus is a simulation apparatus for creep deformation characteristics of a resin molded part, including a speed calculation unit.

  In addition to the first feature, the present invention has three types of contents corresponding to the three types of combinations of the creep deformation characteristics in the load applied to the test piece and the temperature applied to the test piece. Is the second feature.

  According to the present invention, in addition to the first or second feature, the creep deformation characteristic used in the activation energy determining unit is a temperature applied to the test piece with a constant load applied to the test piece. The third feature is that it has two types of contents corresponding to combinations of two types.

  In addition to the first to third features of the present invention, the creep deformation characteristics used in the stress index determination unit may be configured such that the temperature applied to the test piece is constant and the load applied to the test piece is constant. A fourth feature is to have two types of contents corresponding to the two types of combinations.

  In addition to the first to fourth characteristics, the present invention has a fifth characteristic that the time index and speed constant determining unit simultaneously determines the time index and the speed constant.

  In addition to the first to fifth features, the present invention has a sixth feature that the resin molded part is a fiber reinforced resin molded part.

  In addition to the first to sixth features, the present invention has a seventh feature that the test piece is plate-shaped or cylindrical.

Further, according to the present invention, in addition to the first to seventh features, the mathematical expression includes a creep strain rate of dε _c / dt, the rate constant of A (Pa ⁻ⁿ · s ^−m ), and the activation energy. ΔH (J / mol), gas constant R (= 8.31447 J / mol), absolute temperature T (K), stress σ (Pa), stress index n, time t (sec) and time When the index is m, the eighth characteristic is that it is expressed by the following equation (Equation 1).

  According to the first feature of the present invention, a longitudinal elastic modulus corrected by applying FEA to a test piece cut out from a resin molded part by applying FEA based on an elastic deformation characteristic of the test piece is determined. Based on the creep deformation characteristics of the piece, the activation energy is determined using a mathematical formula showing the creep strain rate applying the time hardening rule, and FEA based on the elastic deformation characteristic is applied based on the creep deformation characteristic of the test piece. The stress index is determined using a mathematical formula in which the corrected stress is substituted, and the time index and the speed constant corrected together are determined by applying FEA based on the creep deformation characteristics. Therefore, it is possible to easily and accurately determine each creep physical property value of the test piece and by extension, the resin molded part. And by using such activation energy, stress index, time index, and rate constant, it is possible to calculate a creep strain rate that is highly consistent with the characteristics of the final resin molded part, which is complicated and requires a lot of measurement and calculation. Simulation of the creep deformation characteristics of resin molded parts in a manner that is universal to the shape and structure of test pieces cut out from resin molded parts that are final products using fiber-reinforced resin materials, etc. It can be performed with high accuracy.

  According to the second feature of the present invention, the creep deformation characteristics of the test piece need only have three types of contents corresponding to the three types of combinations of the load applied to the test piece and the temperature applied to the test piece. The creep deformation characteristics can be measured in a small number of steps and in a short time.

  According to the third feature of the present invention, the creep deformation characteristic of the test piece used in the activation energy determining unit is a combination of two types of temperatures applied to the test piece with a constant load applied to the test piece. Since it is sufficient that there are two types of corresponding contents, the activation energy can be easily determined.

  According to the fourth feature of the present invention, the creep deformation characteristic of the test piece used in the stress index determination unit corresponds to a combination in which the temperature applied to the test piece is constant and the load applied to the test piece is two types. Since it is sufficient if there are two types of contents to be performed, the stress index can be easily determined.

  According to the fifth feature of the present invention, the time index and the rate constant determining unit determine the time index and the rate constant at the same time. Therefore, the time index and the rate constant can be easily determined and the test is performed. It is possible to easily and accurately determine each creep property value of the piece, and by extension, the resin molded part.

  According to the sixth aspect of the present invention, a fiber reinforced resin molded part having a complicated internal structure can be applied as the resin molded part, and the creep deformation characteristics of the resin molded part can be simulated with high accuracy.

  According to the seventh feature of the present invention, a plate-like or cylindrical test piece can be applied as the test piece, and the creep deformation characteristics of the resin molded part can be simulated in a universal manner to the shape and structure of the test piece. Can be performed with high accuracy.

  According to the eighth aspect of the present invention, the creep deformation characteristic of the resin molded part is simulated with high accuracy by using the equation (Equation 1) as a mathematical formula indicating the creep strain rate to which the time hardening rule is applied. be able to.

It is a perspective view of the fiber reinforced resin molded component in the embodiment of the present invention. It is a perspective view of the flat test piece mechanically cut out from the fiber reinforced resin molded component in this embodiment. It is a perspective view of the cylindrical test piece mechanically cut out from the fiber reinforced resin molded component in this embodiment. It is a block diagram which mainly shows the structure of the simulation apparatus of the creep deformation characteristic of the fiber reinforced resin molded component in this embodiment. It is a graph which shows typically the measured creep deformation characteristic curve of the test piece cut out from the fiber reinforced resin molded part in this embodiment. It is a flowchart which shows the process of determining the creep strain rate of the test piece performed using the simulation apparatus of the creep deformation characteristic of the fiber reinforced resin molded component in this embodiment.

  Hereinafter, a simulation apparatus for creep deformation characteristics of a resin molded part according to an embodiment of the present invention will be described in detail with reference to FIGS. In the present embodiment, as a resin molded part, a fiber reinforced resin molded part made of a composite material having a complicated internal structure whose significance is clearly shown by the simulation method of the present embodiment will be described as an example. It can also be applied to resin molded parts made of one material.

  FIG. 1 is a perspective view of a fiber-reinforced resin molded part in the present embodiment. FIG. 2 is a perspective view of a flat test piece mechanically cut out from the fiber-reinforced resin molded part in the present embodiment, and FIG. 3 is mechanically cut out from the fiber-reinforced resin molded part in the present embodiment. It is a perspective view of a cylindrical test piece. FIG. 4 is a block diagram mainly showing a configuration of a simulation apparatus for creep deformation characteristics of a fiber-reinforced resin molded part in the present embodiment. FIG. 5 is a graph schematically showing an actually measured creep deformation characteristic curve of a test piece cut out from a fiber-reinforced resin molded part in the present embodiment, and shows a relationship between time t and strain ε.

  As shown in FIG. 1, the fiber-reinforced resin molded part 10 is typically a rectangular block shape and has a plurality of through holes 12.

  The fiber reinforced resin molded part 10 is a part molded using a fiber reinforced resin material, that is, a glass fiber reinforced resin or a carbon fiber reinforced resin. Specifically, the resin used as a base material is not limited as long as it is a general one. For example, as a thermoplastic resin, polyamide resin such as nylon, PBT resin (polybutylene terephthalate resin) Thermoplastic saturated polyester resins such as PPS resin (polyphenylene sulfide resin) having heat resistance can be used, and unsaturated polyester resins and phenol resins can be used as thermosetting resins. In addition to short glass fibers and long glass fibers, carbon fibers such as carbonized acrylic fibers, carbon fibers such as carbon nanotubes, and resin fibers such as Kepler can be used as the reinforcing fiber. In order to form a combination of the resin and the fiber, the fiber may be aggregated and placed in a mold, and the resin may be laminated, or the resin and the fiber may be mixed and compressed in advance. Alternatively, the resin may be injected by placing fibers in the mold. Further, not only wet carbon type but also dry carbon type fiber reinforced resin can be used.

Further, as shown in FIG. 1, from a portion between the through holes 12 and 12 of the fiber reinforced resin molded part 10 and a peripheral portion of the through hole 12, a flat test piece TP ₁ as shown in FIG. A cylindrical test piece TP ₂ as shown in FIG. 3 is mechanically cut out with a cutting tool or the like (not shown). The locations and shapes of the test pieces TP ₁ and TP ₂ are not limited, and the fiber reinforced resin molded part 1
A suitable shape such as a plate shape or a cylindrical shape may be selected as appropriate in order to reflect the place where the creep deformation characteristic is likely to be lowered due to the arrival of the resin of 0, the orientation of the fiber, or the like and the portion thereof. In the following description, the test pieces TP ₁ and TP ₂ will be individually described when there are items to be specially described, and otherwise they will be described as the test pieces TP ₁ and TP ₂ for convenience. .

Now, since the creep deformation characteristic of the fiber reinforced resin material used for the fiber reinforced resin molded part 10 is strongly time dependent, the creep strain rate dε _c / dt for the test pieces TP ₁ and TP ₂ is time hardening. It can be expressed by the following formula (Formula 2) to which the rule is applied.

Here, A is a rate constant (Pa ⁻ⁿ · s ^−m ), ΔH is activation energy (J / mol), R is a gas constant (= 8.31447 J / mol), T is an absolute temperature (K), σ Is the stress (Pa), n is the stress index, t is the time (sec), and m is the time index. Among them, the rate constant A, the activation energy ΔH, the stress index n, and the time index m are unknown quantities representing the creep characteristics of the fiber reinforced resin material, and these four values are the creep physical property values to be determined. It can be said.

  Therefore, in order to reproduce and predict the creep deformation characteristic of the fiber reinforced resin molded part 10 by simulation, it is necessary to first determine the creep property value of the fiber reinforced resin material. The simulation apparatus 20 has the following configuration.

That is, as shown in FIG. 4, the simulation apparatus 20 includes a longitudinal elastic modulus determination unit 20a, an activation energy determination unit 20b, a stress index determination unit 20c, a time index and rate constant determination unit 20d, and a strain rate. A calculation unit 20e, and other necessary memory and the like. The simulation apparatus 20 is in communication with a deformation characteristic measurement unit 30 that measures the elastic deformation characteristics and creep deformation characteristics of the test pieces TP ₁ and TP ₂ that are mechanically cut out from the fiber-reinforced resin molded part 10.

Here, the creep deformation characteristic curves of the test pieces TP ₁ and TP ₂ cut out from the fiber reinforced resin molded part 10 are actually measured by the deformation characteristic measuring unit 30 and show a change with time of the strain ε as shown in FIG. . Here, ε _e is the elastic strain in the elastic deformation region, ε _c is the creep strain in the creep deformation region, and dε _c / dt is the creep strain rate in the creep deformation region. Specifically, when a load is applied to the test pieces TP ₁ and TP ₂ , the elastic deformation is performed up to ε _{2 in} a short time, and then the creep deformation is performed. Such creep deformation region includes a transition creep deformation region after elastic deformation, and a constant creep deformation area subsequent thereto, asymptotic value of the constant creep deformation is epsilon _1. Further, the creep strain rate dε _c / dt can be calculated by differentiating the creep strain ε _c with respect to time.

That is, in the simulation apparatus 20 that the deformation characteristic measuring unit 30 communicates in this way, the longitudinal elastic modulus determining unit 20a is based on the elastic deformation characteristics of the test pieces TP ₁ and TP ₂ measured by the deformation characteristic measuring unit 30. Is applied, and the activation energy determination unit 20b determines the equation (several numbers) based on the creep deformation characteristics of the test pieces TP ₁ and TP ₂ measured by the deformation characteristic measurement unit 30. 2) is used to determine the activation energy ΔH, and the stress index determination unit 20c is corrected based on the creep deformation characteristics of the test pieces TP ₁ and TP ₂ measured by the deformation characteristic measurement unit 30 and is corrected. The stress index n is determined using the formula (Equation 2) in which the stress corrected by applying FEA using is substituted, and the time index and rate constant determining unit 20d While based on the creep deformation characteristics of the characteristic measuring section 30 specimens TP 1 which has been _measured, TP _2, the stress exponent activation energy activation energy determination section 20b has determined and stress exponent determination unit 20c decides is substituted formula The time index m and the rate constant A corrected together by applying FEA using (Equation 2) are determined, and the strain rate calculation unit 20e determines the activation energy and stress index determined by the activation energy determination unit 20b. The creep strain rate is calculated by substituting the time index and rate constant determined by the determination unit 20c for the stress index, time index, and rate constant determination unit 20d into the equation (Equation 2).

Each step of deriving the creep physical property values of the test pieces TP ₁ and TP ₂ and obtaining the creep strain rate using the simulation apparatus 20 having the above configuration will be specifically described below with reference to FIG.

  FIG. 6 is a flowchart showing a process of determining the creep strain rate of the test piece, which is executed using the simulation apparatus for creep deformation characteristics of the fiber-reinforced resin molded part in the present embodiment.

  As shown in FIG. 6, first, in step S1, a fiber reinforced resin molded part 10 as shown in FIG. 1 is prepared.

Next, in step S2, test pieces TP ₁ and TP ₂ as shown in FIGS. 2 and 3 are appropriately selected from the fiber reinforced resin molded part 10 and mechanically cut out.

Next, in step S3, the test pieces TP ₁ and TP ₂ selected and cut out are arranged in the deformation characteristic measuring unit 30, and the constant load P is applied while maintaining the test pieces TP ₁ and TP ₂ at a constant temperature. And a creep deformation characteristic curve as shown in FIG. 5 for the test pieces TP ₁ and TP ₂ is measured.

Specifically, when using a test piece TP _1, as shown in FIG. 2, a cylindrical support member 14, 16 respectively abut against the longitudinal ends of the test piece TP _1, the test piece TP ₁ the longitudinal central portion bent pressed with a load P from the opposite side of the support 14 and 16, to measure the creep displacement generated in the direction perpendicular to the plane in the longitudinal direction of the central portion of the test piece TP _1. On the other hand, when using the test piece TP ₂ , as shown in FIG. 3, the flat plate-like support tool 18 is brought into contact with the test piece TP _{2 in} the axial direction, and the test piece is viewed from the opposite side of the support tool 18. The outer surface of the cylindrical portion of TP ₂ is compressed by pressing with a load P uniformly in the radial direction in the axial direction, and creep displacement generated in the radial direction in the cylindrical portion of the test piece TP ₂ is measured.

Here, three types of creep deformation characteristic curves for the test pieces TP ₁ and TP ₂ to be measured are required. That is, for example, when applying a constant load _{P a} while maintaining the test piece _TP 1, TP ₂ at a constant temperature _{T a,} the constant load _{P b} while maintaining the test piece _TP 1, TP ₂ at a constant temperature _{T a} If applied, and it is necessary to measure the three types of creep deformation characteristic curves in a case of applying a constant load P _a while maintaining the test piece TP _1, TP ₂ at a constant temperature T _b. The temperatures T _a and T _b and the loads P _a and P _b are within a predetermined range corresponding to an environment such as an automobile to which the fiber-reinforced resin molded part 10 is actually applied, typically, environmental requirements. It is preferable from the viewpoint of improving the reproducibility of the simulation that the temperature and the load are each set within a range including each range.

Next, in step S4, the longitudinal elastic modulus E of the test pieces TP ₁ and TP ₂ is determined.

Specifically, for the test piece TP ₁ , first, an initial value E ₀ of the longitudinal elastic modulus E is calculated using an equation (Equation 3) within the elastic deformation range. Here, in the test piece TP _1, as shown in FIG. 2, the length L (m), the a b (m) and the height width and h (m).

In such equation (3), since the test piece TP ₁ it is necessary to know the load P _e and the elastic displacement [delta] _e to elastically deform, as shown in FIG. 2, support the longitudinal ends of the test piece TP ₁ 14 and 16 each contact, bending and pressed with a load _{P e} a longitudinal center portion of the test piece TP ₁ from the opposite side of the support 14, 16. At this time, pressing is performed while increasing the load _Pe from 0, and the elastic displacement δ _e generated in the direction perpendicular to the surface at the center in the longitudinal direction of the test piece TP ₁ is measured over time, and a load-elastic displacement curve is obtained. Get. The maximum value of the elastic displacement [delta] _e is the maximum value of the elastic displacement of the test piece TP _1, in FIG. 5 corresponds to the value of the strain epsilon _2.

Then, the initial elastic displacement δ _e0 is obtained from the linear region of the actually measured load-elastic displacement curve, and the load P _e0 and the initial elastic displacement δ _e0 are substituted into the equation (Equation 3) to obtain the initial value of the longitudinal elastic modulus E. E ₀ is calculated.

Here, the equation (Equation 3) holds when the deformation amount of the test piece TP ₁ is small, and the shape nonlinearity cannot be ignored when the deformation amount of the test piece TP ₁ becomes large. Repeat FEA Te, it is necessary to generalize the value of the modulus of longitudinal elasticity E from the initial value E _0. Therefore, specifically, the FEA is repeated so that the load-displacement curve reproduced using the initial value E ₀ of the longitudinal elastic modulus E fits the actually measured load-elastic displacement curve, and the longitudinal elastic modulus E Correct the value from the initial value E _0, determines the value of the unique longitudinal elastic modulus E.

On the other hand, for the test piece TP ₂ , similarly, the support tool 18 is contacted along the axial direction of the test piece TP ₂ , and the outer surface of the test piece TP ₁ is made uniform in the axial direction from the opposite side of the support tool 18. toward the radially compressed by pressing at P _e. At this time, the load P _e continue pressing with increasing from 0, by measuring the elastic displacement [delta] _e occurring in the radial direction in the cylindrical portion of the test piece TP _2, the load - obtain elastic displacement curve. However, for the test piece TP _2, it is complicated to obtain a mathematical expression corresponding to the expression (Equation 3). Therefore, obtaining the initial value E ₀ of the longitudinal elastic modulus E is omitted, and an arbitrary initial value E ₀ is set. load was reproduced using - displacement curve, the actually measured load - Repeat FEA to curve fit to the elastic displacement curve, the value of the modulus of longitudinal elasticity E and modified from the initial value E _0, unique longitudinal elastic modulus E Find the value of.

Incidentally, the load of such a test piece _TP 1, TP ₂ of the elastic displacement [delta] _e - elastic displacement curve, sufficient by measuring a test piece _TP 1, TP ₂ was maintained at room temperature, such measurements, the test piece in the step S3 may be performed before the measurement of the creep deformation characteristic curves of TP _1, TP _2, may be performed by cutting the same manner specimen TP _1, TP ₂ from a fiber reinforced plastic molded component 10 separately prepared.

Of course, if necessary, the initial value E ₀ of the longitudinal elastic modulus E is set to an arbitrary value without obtaining the equation (Equation 3), and the FEA is repeated for the test piece TP ₁ to obtain the longitudinal elastic modulus E. It may be determined uniquely. Further, for the test piece TP ₂ , a mathematical formula corresponding to the formula (Equation 3) is obtained, an initial value E ₀ of the longitudinal elastic modulus E is set, and FEA is repeated to uniquely obtain the longitudinal elastic modulus E. Good.

  Now, in step S5 to step S7, each creep property value is obtained.

First, in step S5, the activation energy ΔH is obtained. Specifically, with respect to the equation (Equation 2), the following equations (Equation 4) and Equations (Equation 5) can be obtained by creating simultaneous equations by combining any one stress σ and any two temperatures T _a and T _b. Therefore, the following formula (formula 6) is obtained by dividing the formula (formula 4) by the formula (formula 5) and organizing the activation energy ΔH while taking the logarithm.

Here, the activation energy ΔH expressed by the equation (Equation 6) is expressed by the temperatures T _a and T _b and the corresponding creep strain rates (dε _c / dt) _{T = Ta} and (dε _c / dt) _{T = If Tb is known,} it can be obtained. Specifically, creep strain rates (dε _c / dt) _{T = Ta} and (dε _c / dt) _{T = Tb} respectively corresponding to the temperatures T _a and T _b are expressed as follows for the test pieces TP ₁ and TP ₂ : test piece _TP 1 was measured in step S3, when the TP ₂ by applying a constant load _{P a} while maintained at a constant temperature _{T a,} and the test piece _TP 1, constant while maintaining the TP ₂ at a constant temperature _{T b} load P If two types of creep deformation characteristic curves when _a is applied are used, creep strains at temperatures T _a and T _b (ε _c ) _{T = Ta} and (ε _c ) _{T = Tb} are obtained by first-order differentiation with respect to time. Therefore, the temperatures T _a and T _b and the creep strain rate (dε _c / dt) _{T = Ta} and (dε _c / dt) _{T = Tb} are substituted.

Thus substituting the temperature _{T a} and the temperature _{T b} respectively correspond to the creep strain rate obtained in this way in _{(dε c / dt) T =} Ta, the _{(dε c / dt) T =} Tb equation (6) Then, the activation energy ΔH is determined.

Next, in step S6, a stress index n is obtained. Specifically, with respect to the equation (Equation 2), the following equations (Equation 7) and Equations (Equation 8) can be obtained by creating simultaneous equations with a combination of any one temperature T and any two stresses σ _a and σ _b. Therefore, if the logarithm is taken and the formula (formula 7) is divided by the formula (formula 8) and the stress index n is arranged, the following formula (formula 9) is obtained. The stresses σ _a and σ _b correspond to the loads P _a and P _b , respectively.

Here, the stress index n shown in the equation (9) is the stress σ _a , σ _b and the corresponding creep strain rate (dε _c / dt) _{σ = σa} , (dε _c / dt) _{σ = σb} If you know that. Specifically, creep strain rates (dε _c / dt) corresponding to the stresses σ _a and σ _{b σ = σa} and (dε _c / dt) _{σ = σb} are _{expressed as} follows with _respect to the test pieces TP ₁ and TP ₂ . test piece _TP 1 was measured in step S3, when the TP ₂ by applying a constant load _{P a} while maintained at a constant temperature _{T a,} and the test piece _TP 1, constant while maintaining the TP ₂ at a constant temperature _{T a} load P If two types of creep deformation characteristic curves when _b is applied are used, the creep strains (ε _c ) _{σ = σa} and (ε _c ) _{σ = σb} when stresses σ _a and σ _b occur are expressed as first order over time. Since they can be obtained by differentiation, the stresses σ _a and σ _b , and the creep strain rate (dε _c / dt) _{σ = σa} and (dε _c / dt) _{σ = σb} are substituted respectively.

However, the stress when the deformation amount of the test pieces TP ₁ and TP ₂ is small is proportional to the applied load. However, when the deformation amount of the test pieces TP ₁ and TP ₂ is large, the shape nonlinearity cannot be ignored. As the stresses σ _a and σ _b used for deriving the stress index n, those corrected by FEA using the longitudinal elastic modulus E previously corrected in step S4 are used. Specifically, with respect to the test pieces TP ₁ and TP ₂ , the maximum stress value at the end of elastic deformation in the load-elastic displacement curve reproduced using the longitudinal elastic modulus E that has been corrected in advance in step S4 is the step S4. The stress value is corrected by repeating FEA so as to coincide with the maximum stress value at the end of elastic deformation obtained from the load-elastic displacement curve actually measured in step ₁ , and the stresses corrected respectively corresponding to the loads P _a and P _b Are used as stresses σ _a and σ _b used to derive the stress index n.

Accordingly, the stresses σ _a and σ _b thus obtained and the creep strains (ε _c ) _{σ = σa} and (ε _c ) _{σ = σb} obtained corresponding to them are substituted into the equation (Equation 9). Determine the stress index n.

Next, in step S7, a time index m and a speed constant A are obtained. Here, the time index m is a factor indicating the time dependence of the creep deformation characteristics, and particularly has a strong influence on the behavior of the transition creep. When the time index m is small, the transition creep time is short, While the creep deformation converges rapidly and shifts to steady creep, when the time index m is large, the transition creep time becomes long and the transition creep deformation tends to be difficult to converge. The rate constant A is a factor that determines the absolute value of the creep strain rate. When the value of the rate constant A is small, the creep strain rate is small. On the other hand, when the value of the rate constant A is large, the creep strain rate is large. Tend to be. That is, since the time index m and the rate constant A are factors that have a mutual influence on the creep deformation characteristics, in step S7, the time index m and the rate constant A are simultaneously adjusted. It will be decided.

Specifically, for example, as an actually measured creep deformation characteristic curve, a creep deformation characteristic curve in a case where _a constant load Pa is applied while maintaining the test pieces TP ₁ and TP ₂ measured in step S3 at _a constant temperature Ta. used for equation (2), the temperature T _a, previously modified stress sigma _a, activation energy ΔH calculated in step S4 in step S6 in response to the load P _a, the stress exponent obtained in step S5 n, to start the FEA by substituting each arbitrary initial value a ₀ of arbitrary initial value m ₀ and rate constant a of the time index m, to reproduce the creep deformation characteristic curve. Then, the creep deformation characteristic curves in a case of applying a constant load P _a while maintaining the test piece TP _1, TP ₂ actually measured in step S3 at a constant temperature T _a, the amount of deformation of the convergence state of the transition creep region While repeating the FEA while adjusting the value of the time index m and the value of the rate constant A while observing the value of the creep strain rate in the entire creep region and the creep region, the creep deformation characteristic curve reproduced by the FEA is the measured creep deformation. If a state fitted to the characteristic curve is obtained, the value of the time index m and the value of the speed constant A at that time are determined as the value of the time index m and the value of the speed constant A corrected by FEA.

In step S8, the creep physical property values determined as described above are substituted into the equation (Equation 2) to obtain the creep strain rate dε _c / dt for either of the test pieces TP ₁ , TP ₂ , The creep deformation characteristics of the fiber reinforced resin molded part are predicted by simulation, and this series of processing is completed.

  In addition, the order of each step of the above step S5 and step S6 is not limited, and may be mixed.

  According to the configuration of the above embodiment, the longitudinal elastic modulus corrected by applying FEA based on the elastic deformation characteristics of the test piece is determined for the test piece cut out from the resin molded part, and the test is performed. Based on the creep deformation characteristics of the piece, the activation energy is determined using a mathematical formula showing the creep strain rate applying the time hardening rule, and FEA based on the elastic deformation characteristic is applied based on the creep deformation characteristic of the test piece. By determining the stress index using a formula substituted with the corrected stress and applying FEA using the formula substituted with the activation energy and the stress index based on the creep deformation characteristics, Because it determines the modified time index and rate constant, it can easily and accurately determine the creep property values of the test piece and hence the resin molded part. Rukoto can. Then, by substituting the activation energy, stress index, time index, and rate constant into the mathematical formula, a creep strain rate that is highly consistent with the characteristics of the final resin molded part can be calculated. Creep deformation of such resin molded parts in a universal manner with respect to the shape and structure of the test piece cut out from the resin molded part, which is the final product using fiber reinforced resin material, etc. Characteristic simulation can be performed with high accuracy.

  In the present invention, the type, arrangement, number, and the like of the members are not limited to the above-described embodiments, and the constituent elements thereof are appropriately replaced with those having the same operational effects, and the gist of the invention is not deviated. Of course, it can be appropriately changed within the range.

As described above, in the present invention, the shape and structure of a test piece cut out from a resin molded part which is a final product using a fiber reinforced resin material or the like without complicated and a large amount of measurement and calculation. It is possible to provide a simulation device that can perform the simulation of creep deformation characteristics of resin molded parts with high accuracy in a universal manner, and in the field of simulation of creep deformation characteristics because of its universal character. It is expected to be widely applicable.

DESCRIPTION OF SYMBOLS 10 ... Fiber reinforced resin molded component 12 ... Through-hole 14 ... Support tool 16 ... Support tool 18 ... Support tool 20 ... Simulation apparatus 20a ... Longitudinal elastic modulus determination part 20b ... Activation energy determination part 20c ... Stress index determination part 20d ... Speed Constant determining unit 20e ... Strain rate calculating unit 30 ... Deformation characteristic measuring unit

Claims (8)

A longitudinal elastic modulus determination unit that determines a corrected longitudinal elastic modulus by applying a finite element analysis based on the elastic deformation characteristics of a test piece cut out from a resin molded part;
Based on the creep deformation characteristics of the test piece, the activation energy is determined using a mathematical formula showing a creep strain rate applying a time hardening rule with an activation energy, a stress index, a time index, and a rate constant as a creep property value. An activation energy determining unit to perform,
A stress index determination unit that determines the stress index using the mathematical formula in which the stress corrected by applying a finite element analysis using the longitudinal elastic modulus is substituted while based on the creep deformation characteristics;
A time index and rate constant determining unit for determining the time index and the rate constant modified together by applying a finite element analysis while being based on the creep deformation characteristics;
A strain rate calculation unit that calculates a creep strain rate by substituting the activation energy, the stress index, the time index, and the rate constant into the formula;
An apparatus for simulating creep deformation characteristics of a resin molded part, comprising:   2. The resin molded part according to claim 1, wherein the creep deformation characteristic has three types of contents corresponding to three types of combinations of a load applied to the test piece and a temperature applied to the test piece. A creep deformation simulation device.   The creep deformation characteristic used in the activation energy determining unit has two types of contents corresponding to a combination in which a load applied to the test piece is constant and two temperatures are applied to the test piece. The simulation apparatus for creep deformation characteristics of a resin molded part according to claim 1 or 2.   The creep deformation characteristic used in the stress index determination unit has two types of contents corresponding to a combination of two types of loads applied to the test piece while keeping a temperature applied to the test piece constant. The simulation apparatus for creep deformation characteristics of a resin molded part according to any one of claims 1 to 3.   The said time index and speed constant determination part determines the said time index and said speed constant simultaneously, The simulation apparatus of the creep deformation characteristic of the resin molded component in any one of Claim 1 to 4 characterized by the above-mentioned.   6. The simulation apparatus for creep deformation characteristics of a resin molded part according to claim 1, wherein the resin molded part is a fiber reinforced resin molded part.   The said test piece is plate shape or cylindrical shape, The simulation apparatus of the creep deformation characteristic of the resin molded part in any one of Claim 1 to 6 characterized by the above-mentioned. In the above equation, the creep strain rate is dε _c / dt, the rate constant is A (Pa ⁻ⁿ · s ^−m ), the activation energy is ΔH (J / mol), and the gas constant is R (= 8.331447 J / ^m ). mol), the absolute temperature is T (K), the stress is σ (Pa), the stress index is n, the time is t (sec), and the time index is m. The simulation apparatus for creep deformation characteristics of a resin molded part according to any one of claims 1 to 7.

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