Structural Analysis of Components Obtained by the Injection Molding Process

André Antunes Oliveira [email protected]

Instituto Superior Técnico, Lisboa, Portugal April 2016

Abstract The mechanical properties of components manufactured using the injection molding process depend on the characteristics of its constituent material, the processing conditions used and, ultimately, on the part’s geometry. This parameters have a strong influence on process resultant variables, like the material flow, the fiber orientation, the internal stress fields and, consequently, the warpage. Thus, the material obtained under these conditions has different properties than the ones initially provided by the manufacturer, causing structural changes in each component, which subsequently modify its load performance.

Injection simulation programs, such as Autodesk Moldflow, computationally reproduce each step of this process. In order to implement the manufacturing history of each injection molded component on the reproduction of its loading behavior, it is required the integration of the injection simulation results in programs able to carry out its structural analysis. This way, the finite element analysis programs, such as Simulia Abaqus, allow the determination of the mechanical behavior of a loaded part considering its manufacturing biography (in cavity stress field, residual strains, fiber orientation). The interaction between these software can be accomplished directly, or using external interfaces, like Helius PFA.

This work aims to couple the manufacturing history of injection molded components, as well as the material experimental information, in the prediction of its loading behavior. Thus, this study intends to increase the accuracy of structural analysis performed on injection molded parts.

Keywords: Injection Molding Simulation, Autodesk Moldflow, Finite Element Analysis, Simulia Abaqus, Residual Stress, Product Performance

molded components, it’s required an upgrade on 1 Introduction the prediction of process resultant residual stress fields. The injection molding process causes structural changes in each component, which This work aims for two fundamental subsequently modify its performance under a accomplishments. The first one is the service load. These changes are caused by the optimization of forecasting injection molded accumulation of stress during the part’s filling in components’ loading behavior, which results on the mold cavity, resulting on warpage that the improvement of the prediction of process deforms its geometry after manufacture. Thus, resultant residual stress distribution. This is the component’s deformation and shrinkage intended to be achieved coupling the parts’ generate residual stress fields, functioning as an manufacturing history in its structural analysis indicator of the effects caused by the and, subsequently, evaluating its effects on the manufacturing process on the part’s structural product performance. The second integrity. Therefore, in order to accurately accomplishment of this work is to increase the reproduce the loading performance of injection accuracy of structural analyses of injection

1 molded components, using the material competitiveness of this market, emerge as the experimental data as well. major drawbacks of this process.

2.1.1 Residual Stress 2 Background By definition, residual stresses are elastic stress fields that remain in a solid material 2.1 Injection Molding Process without any external loads or temperature The injection molding process is one of the gradients applied. These stresses are the result of most common manufacturing techniques for the the part’s deformation and shrinkage after its mass production of polymer components. It is ejection from the mold, when the in cavity based on four major stages [1]: constraints are released. Furthermore, residual stresses have a similar effect on a structure than 1. Filling - Initially the polymer contained externally applied forces, which can lead to the in a hopper, usually in the form of pellets, part’s resistance reduction and, ultimately, its is leaked to the surface of a rotating early failure. There are two kinds of residual screw that pushes it into the mold. The stresses: the flow induced and the thermal screw rotation causes the contact of the induced [2]. plastic pellets with the hot cylinder walls, melting due to the heat of compression, The flow induced residual stresses are the friction and the high surface developed during the filling phase. Subsequently, temperature. When there is enough they are the result of contact between the oriented molten material in the screw end, it and disoriented layers of material, due to high paralyzes and injects the molten plastic cooling rates and shear stresses [2]. in the mold cavity through a feed system; The thermal induced residual stresses 2. Packing – this phase begins when 95% to are the result of the part’s unbalanced cooling 98% of the cavity has been filled. This and differential shrinkage [2]. moment is called the velocity/pressure switch-over point, when there is a 2.1.2 In-Cavity Stress Field switch-over from ram speed control to packing pressure. During this phase, While the component is still confined further pressure is applied to the material into the mold cavity, the internal stress field that in an attempt to pack more material into is developed during the material solidification is the cavity. This is intended to produce a called in-cavity stress. In practice, in-cavity reduced and more uniform shrinkage stresses are the driving force of the part’s with less component warpage. warpage and shrinkage after ejection [2]. 3. Cooling – Simultaneously, the mold is 2.1.3 Residual Strain cooled down using a coolant to lower the temperature of the plastic part. Once the The configurations before and after the polymer solidifies, the cavity pressure is part’s ejection are exhibited in Figure 1. In A the reduced to atmospheric pressure. This part is still confined into the mold cavity, while stage ends when the part reaches a safe cools down to achieve room temperature. Using extraction temperature; the Hooke’s Law of equation (1), the stress and 4. Ejection – Finally, when the component strain fields of configuration A are easily is fully solidified, the mold is opened and obtained (equation (2)). In this configuration the the part is ejected. The mold is then resulting stress field, {휎퐴}, is nonzero, unlike the closed so that a new cycle can begin. strain field, {휀퐴}. However, there are residual strains, {휀푛푚}, due to shrinkage when the part is The injection molding process has many into the mold, calculated using the in-cavity advantages, such as its suitability to large stress field, {휎퐴} (equation (2)) [3]. production volumes, obtaining complex geometry parts that require fewer finishing When the mold is removed the scheme operations. However, the high cost of the B it’s obtained, in which the part warps and required equipment and the great develops residual stresses, {휎퐵}. This way, the

2 effect of residual strain can be incorporated in the These tensor’s eigenvectors indicate the residual stress field calculation (equation (3)), main directions of fiber alignment, assuming that accounting for process resultant shrinkage [3]. the material is orthotropic. Thus, its eigenvalues provide a measure of the degree of fiber { } [ ]{ } 휎 = 퐶 휀 (1) alignment of the material. A perfectly aligned

{휎퐴} = [퐶]({휀퐴} − {휀푛푚}) ⇔ composite has fiber orientation tensor eigenvalues of (1,0,0), unlike a randomly aligned ⇔ {휀 } − [퐶]−1{휎 } = {휀 } ⇔ 퐴 퐴 푛푚 (2) material, whose eigenvalues are (1/3,1/3,1/3) [3]. ⇔ {휀 } = −[퐶]−1{휎 } 푛푚 퐴 (4) 푎푖푗 = ∫ 푝푖푝푗휑(푝)푑푝 {휎퐵} = [퐶]({휀퐵} − {휀푛푚}) (3) (5) 푎푖푗푘푙 = ∫ 푝푖푝푗푝푘푝푙휑(푝)푑푝

2.2.2 Mori Tanaka micro-mechanics Model The mechanical properties of fiber reinforced materials depend on the direction, as a result of fiber alignment, being often called orthotropic materials. The micro-mechanical models provide a theoretical way to obtain the mechanical properties of a composite based on properties of its constituents (matrix and fibers).

The Mori Tanaka micro-mechanical Figure 1 – Stress and strain fields before and model is widely used to calculate the mechanical after the part’s ejection [3]. properties of a composite material. Initially, the matrix and fiber constituent materials stiffness 2.2 Injection of Fiber Reinforced matrixes are combined (퐶푚 and 퐶푓, respectively) in order to obtain the composite stiffness matrix, Thermoplastics 퐶퐶, as shown in equations (6) to (8). Afterwards, A fiber reinforced material, also named this model calculates the material mechanical as a composite, is a combination of two properties using the Hooke’s Law in equation constituent materials: the matrix and the fibers. (1). Therefore, the matrix main function is to keep the 퐶퐶 = 퐶푓 + 푣 (퐶푓 − 퐶푚)퐴 (6) fibers together, securing them and acting as a 푓 −1 (7) mean of load transfer. There are short and long 퐴 = 푇[(1 − 푣푓)퐼 + 푣푓푇] fiber reinforced materials, as well as different 푇 = [퐼 + 푆(퐶푚)−1(퐶푓 − 퐶푚)]−1 (8) fiber orientations available (for instance, perfectly aligned or randomly aligned). Nevertheless, 푆 represents the Eshelby Composite materials are in fact commonly used tensor, 퐴 is the strain concentration tensor and is in the injection molding process, in order to 푣푓 the fiber volume fraction.

improve components’ stiffness, resistance and other mechanical properties [4]. 2.3 Numerical Analysis Tools 2.2.1 Fiber Orientation Tensor 2.3.1 Injection Simulation The second and fourth order fiber orientation tensors, shown in equations (4) and The selected software to perform (5), provide a statistical description of the injection simulations was Autodesk Moldflow direction of the fibers in a certain point of the Insight 2016. This software allows the user to domain. This way, the probability density simulate the various steps of the injection function, 휑(푝), describes the behavior of a set of molding process, through different analysis fibers in a given direction [5]. modules that can be used alone or sequentially,

3 such as filling, packing, cooling and warpage. (donor mesh) different from the one Moldflow has also an extensive material used for the structural analysis properties database. (receiving mesh), mapping information from one model to another. The 2.3.2 Finite Element Analysis interface used for this study was Helius Abaqus 6.14-1 was the chosen structural Progressive Failure Analysis. analysis software, which has a wide range of Thus, these two methods combine the FEM solutions. [6]: structural analysis and the part’s manufacturing The current research aims to integrate the history, using injection simulation results such as injection simulation results in structural analysis. in-cavity stress field, residual strains or the fiber Thus, it is essential to implement a solution that orientation tensor of a composite material. allows Abaqus receive all information from Moldflow without affecting these results. 3 Implementation One of the key elements of a structural static 3.1 Direct Method of Data analysis is the application of constraints, limiting certain degrees of freedom of the model. An Transfer Abaqus structural analysis is a group of The initial study aims to define sequential steps, which are sets of time methodologies and settings to be implemented increments, each with the respective loads and during the injection simulation, allowing to boundary conditions. Thus, the nature of the accurately transfer its results to the structural boundary conditions of each step requires further analysis. In addition, it requires the creation of study, and especially in the initial step, since it’s suitable conditions in the structural analysis to the one in which the injection simulation results process the injection data. The assessment made are managed. in this chapter was based on the observation of deformations and residual stresses of each model. 2.4 Coupling of Injection The direct transfer method enables the Simulation Results to usage of the injection mesh in the structural analysis, allowing a closer observation and Structural Analysis assessment of the different responses of the mesh In order to couple the manufacturing deformed shape depending on the various history of a component in its structural analysis settings implemented. This way, that was the and, this way, predict the process resultant selected method in this chapter to transfer the residual stress field, it’s mandatory to import the injection simulation results to Abaqus. injection simulation results to a FEA software. Figure 2 shows the flowchart of the Therefore, this can be accomplished using two direct transfer method using Abaqus Interface for different methods: Moldflow as a compiler. Moldflow imports to 1. Direct transfer of the injection Abaqus data related to the mesh undeformed simulation data to structural analysis, shape, the material properties, the in-cavity stress using the Abaqus Interface for field and the fiber orientation tensor. In addition, Moldflow as a compiler. This method this method automatically adds constraints in doesn´t require any mapping between three degrees of freedom of the part, in order to meshes, using the same configuration in eliminate its rigid body motion. Abaqus Interface both analysis (injection simulation and for Moldflow then converts this information into structural analysis); a structural model, in order to be Abaqus 2. Transmitting the injection simulation compatible [7]. results to external interfaces, which have solvers that allow its mapping to structural programs. This method involves the use of an injection mesh

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Figure 2 - Flowchart of the direct transfer of the Moldflow simulation data to Abaqus analysis.

3.1.1 Mesh tetra element mesh (C3D4 in Figure 4). Subsequently, Abaqus Interface for Moldflow Moldflow offers three different types of enables its translation from C3D4 to C3D10 mesh: Midplane, Dual Domain and 3D. (Figure 4), a 10-node tetra mesh. That way, this Midplane and Dual Domain meshes are suitable transfer method keeps the mesh topology intact, for shell models, due to its bi-dimensional giving the option of changing its elements triangular elements. Nevertheless, 3D meshes are constitution in the structural analysis [7]. built on 4-node tetrahedrons, especially designed for thick solid parts. For that matter, 3D mesh (a) (b) was adopted for this work injection simulations [3].

3.1.1.1 Quality Mesh quality is one of the major factors Figure 4 – a) C3D4. b) C3D10. [9] for the accuracy of the final results. The most As a result, the injection mesh quality important indicator of an injection 3D mesh standards of aspect ratio need to be compatible quality is the aspect ratio. The aspect ratio of an with the structural limits as well. However, the element is the relation between its width and automatic repair of 3D elements aspect ratio, height, a/b of Figure 3. A perfect element performed in Moldflow, can’t overcome this exhibits an aspect ratio of 1 [8]. problem in every single mesh element, leaving elements with insufficiently refined aspect ratios in complex geometry and thickness variation zones (dark blue in Figure 5). This elements can Figure 3 – Triangular aspect ratio [8]. damage the accuracy of the structural analysis. Both injection and structural meshes require limit values of aspect ratio of its elements, in order to be considerate a qualitatively approved mesh. The maximum allowable aspect ratio of an injection 3D mesh is 30, while for a structural mesh is 10.

When transferring directly the injection simulation results to the structural analysis, the injection mesh is imported to Abaqus as a 4-node Figure 5 - 3D injection mesh repair results in Autodesk Moldflow. 3.1.1.2 Aggregation The injection simulation analysis sequence was established as filling, packing and warpage. Thus, Moldflow assumes the uniform cooling of the part during the process simulation. Furthermore, Moldflow has three mesh options in order to perform its warpage analysis [8]:

1. Using the 3D mesh with linear Figure 6 – Weak springs applied in the elements, as in the filling and packing structural and injection models. analysis phases; 2. Update the linear tetrahedral elements 3.2 Helius PFA of the 3D mesh to second order (quadratic) using a different mesh than Moldflow’s inability to incorporate the in the filling and packing stages; material experimental data in the injection 3. Mesh aggregation. This technique simulation and, subsequently, transfer directly reduces the mesh number of layers for this results to Abaqus, demanded the study of a two (instead of the six used by default), new interface. Thus, Figure 7 shows the while updating each element to the flowchart of the direct transfer method using second order. Helius PFA.

The assessment of the influence of the type Helius PFA is a program developed by of element and the mesh aggregation option in Autodesk, which has a tool called Advanced the injection simulation, required the analysis of Material Exchange (AME) that allows the four models in parallel: mapping of fiber orientation tensor and residual strains from the injection simulation to the 1. Moldflow Quadratic → Abaqus structural analysis. This transfer method maps C3D10 information from a donor mesh (injection) to a receiving mesh (structural), both different from 2. Moldflow Linear → Abaqus C3D4 each other. AME has different tools to optimize 3. Moldflow Aggregation → Abaqus the mapping ability, such as the model alignment C3D10 or mapping suitability plot [3].

4. Moldflow Aggregation → Abaqus Furthermore, Helius PFA homogenizes C3D4 and decomposes the material stress and strain fields into their constituent (matrix and fibers) 3.1.2 Boundary Conditions average values, in order to improve the structural In order to allow the part’s shrinkage analysis accuracy. The homogenization and and warpage using the in-cavity stress field, it decomposition process is established using the was implemented in the structural analysis an Mori Tanaka micromechanical model, as well as initial step free from loading or constraints. the fiber orientation averaging [3]. However, it demands the application of artificial Helius PFA implements the material mechanisms in this step to remove the rigid body experimental stress-strain data in the structural motion. Thus, there were two studies performed: analysis, using a combination of the modified 1. Strategic application of low stiffness Ramberg-Osgood model (equation (9)) and the springs (Figure 6); modified Von Mises stress (equation (10)), to 2. Energy stabilization of the model. predict its plastic behavior. The yielding occurs Abaqus automatic energy stabilization when equations (8) and (9) have equal values [3].

mechanism applies damping in the 1/푛 휎ℎ = 퐸1/푛(휎 )(푛−1)/푛(휀푝 ) (9) structural model, dissipating a small 푌 0 푒푓푓 fraction of the deformation energy. 1 (훼휎 − 훽휎 )2 + (훽휎 − 훽휎 )2 + (10) 휎 = √ [ 11 22 22 33 ] Thus, it is required the energetic balance 푒푓푓 2 2 2 2 2 (훽휎33 − 훼휎11 ) + 6(휎12 + 휎23 + 휎31) of the model to validate this study [6].

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휎0 is the matrix yield stress, 퐸 is the matrix 훼푚 − 휃 1 (11) 푝 훼 = 휃 + ( ) (휆 − ) Young’s modulus and 휀푒푓푓 is the matrix plastic 휆푚 − 1/2 2 strain. 훼 and 훽 are directional dependence 훽 − 휃 1 (12) 훽 = 휃 + ( 푚 ) (휆 − ) coefficients, accounting for the fibers direction in 휆푚 − 1/2 2 the effective stress equation. They are obtained This chapter aims to implement the using equations (11) and (12), where 휆 is the material experimental data in the structural largest fiber orientation tensor eigenvalue and 휃 analysis, mapping the injection simulation results is the fiber randomness parameter. 휆푚, 훼푚, 훽푚 from one model to another. This way, the study correspond to the case of a strongly aligned performed was based on the comparison between material [3]. the material experimental stress-strain curves and a specimen structural analysis results.

Figure 7 - Flowchart of transferring Moldflow simulation data to Abaqus analysis using Helius PFA. - 3.3 Case Study material data as well. It was considered one structural analysis with the residual In order to reproduce an injection molded strain field and another without it. component loading behavior, it was developed a study using three different approaches: The load step implemented in each of the analysis performed in this chapter is represented 1. Structural Analysis considering the in Figure 8, showing the displacements and undeformed part shape and the material constraints applied on the part. properties used in Moldlow, during injection simulation. Thus, this model does not account for the manufacturing effects of the part; 2. Application of the direct method of transferring the injection simulation results to structural analysis, now applying a load step; 3. Use Helius PFA to map injection simulation resultant variables to Abaqus, implementing the experimental Figure 8 – Load step displacements and constraints.

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4 Results and Discussion defection. Furthermore, its maximum stress location is not this one (Figure 9 c) and d)), 4.1 Direct Method of Data revealing that the mesh aggregation option reorganizes the injection mesh elements with Transfer high aspect ratio, softening the stress results in 4.1.1 Mesh those areas. Basically, the mesh aggregation option performs an isoparametric mapping in the The results of the mesh study are in the critical areas of the injection mesh, allowing the Tables 1 and 2, showing the effects on the repair of the element which present an structural analysis caused by the type of element insufficiently refined aspect ratio. used and the mesh aggregation option in the injection simulation.

Table 1 - Total deflection and residual stress of the models without mesh aggregation. (a) (b)

U [MM] 흈푽푴 [MPA] MIN - MAX MIN - MAX MOLDFLOW 1.12 6.01 - - QUADRATIC x10-15 ABAQUS C3D10 0.0 9.79 0.22 123.22 (c) (d) MOLDFLOW 4.37 5.58 - - LINEAR x10-16 ABAQUS C3D4 0.0 7.81 0.54 66.87

Table 2 - Total deflection and residual stress of Figure 9 – Stress locations. a) Max stress, the models with mesh aggregation. quadratic model without aggregation. b) Max stress, linear model without aggregation. c)

U [MM] 흈푽푴 [MPA] Quadratic model with mesh aggregation. d) MIN - MAX MIN - MAX Linear model with mesh aggregation MOLDFLOW 3.22x 5.94 - - 4.1.2 Boundary Conditions AGGREGATION 10-15 ABAQUS C3D10 0.0 4.06 0.57 55.17 Table 3 shows the results of the studies used to define the boundary conditions of the ABAQUS C3D4 0.0 3.53 0.37 46.05

initial step of the structural analysis, allowing the part to deform and shrink using the in-cavity This study shows that the quadratic stress field and, simultaneously, removing the elements are more flexible, reaching higher rigid body motion. levels of deformation due to its constitution (10- node rather than the linear 4-node). Table 3 - Total deflection and residual stress of The models without mesh aggregation each boundary conditions approach. reached higher stress and deflection results. Figures 9 a) and b) show the maximum stress U [MM] 흈푽푴 [MPA] verified in these models, located on areas of MIN - MAX MIN - MAX thickness variation, in high aspect ratio elements MOLDFLOW 0.0071 2.962 - - (Figure 5). Thus, this values of stress are MOLAS ABAQUS 0.0955 2.126 0.55 55.17 considered to be heterogeneities caused by the MOLAS existence of elements with aspect ratio higher MOLDFLOW 0.2164 2.954 - - than the mesh quality standards. ESTAB. ABAQUS 0.231 2.138 0.57 55.17 Figures 9 c) and d) represent the same ESTAB. location in the models with mesh aggregation, as the maximum stress of the models without it. The application of weak springs affects These models obtained lower results of stress and the structural analysis and the injection

8 simulation, reaching lower levels of minimum 4.2.2 Material Experimental deflection in the spring application zone. Properties The energy stabilization performed in the Figure 12 shows the comparison structural analysis achieved similar values of between the material experimental tensile curves minimum deflection as in the injection (EXP), in each fiber direction, and the stress- simulation, showing it affects insignificantly the strain fields obtained in the structural analysis results. This way, this mechanism is considered with (STRAIN) or without (NO STRAIN) the to be the right choice to allow the component’s injection simulation residual stress. free shrinkage and deformation. The models without residual stress 4.2 Helius PFA reproduced accurately the behavior of the 4.2.1 Mapping experimental tensile curves, for 45° and 90° of fiber alignment. Nevertheless, for 0° of fiber The usage of Helius PFA to transfer the orientation, these models achieved lower levels injection simulation results to the structural of stress and strain prior to the rupture, due to the analysis, demands the mapping of the fiber fact that the fiber in Moldflow’s injection orientation tensor and residual strain form one simulation is not perfectly aligned. model to the other. The injection model used in EXP STRAIN NO STRAIN this study was a plaque and the selected structural 200 model was a specimen. The experimental material data available has stress-strain results in three different fiber orientations: 0°, 45° e 90°. 100 (a) As a result, the specimen needs to be aligned in these directions to perform the mapping, in order [MPA]STRESS 0 to accurately reproduce the part’s behavior in all -0,005 0 0,005 0,01 0,015 0,02 0,025 three fiber orientations of the experimental STRAIN EXP STRAIN NO STRAIN stress-strain curves. The mapping results are 100 shown in the Figures 10 and 11.

50 (b)

STRESS [MPA]STRESS 0 o -0,01 0 0,01 0,02 0,03 0 STRAIN EXP STRAIN NO STRAIN 150

o 100 90 (c)

Figure 10 – Fiber orientation tensor mapping. 50 STRESS [MPA]STRESS 0 -0,012 -0,002 0,008 0,018 0,028 STRAIN Figure 12 - Stress-strain graphs comparing the experimental tensile curves of the material and o the results of structural analysis, in each fiber 0 direction. a) 0°. b) 45° .c) 90°.

The models considering the residual strain, showed a similar behavior. However, the o residual stress field cause the negative translation 9 0 of the curves, forcing the initial shrinkage of the Figure 11 – Residual strain mapping. part.

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4.3 Case Study using residual stresses (STRAIN) stands less deformation levels prior to rupture, than the other Tables 4 and 5 present the results of the one (NO STRAIN), in which these fields were case study performed, in which were applied not considered. Furthermore, the residual strains three different approaches to predict the loading cause a stress boost in the system. behavior of an injection molded component.

Therefore, the coupling of the residual Table 4 - Total deflection and stress in the strains in the structural analysis decreases the direction of loading, obtained in the Abaqus part’s resistance to failure, forecasting its loading Standard and the direct transfer case studies. behavior with much more reliability. Thus, this study showed the importance of considering the U [MM] 흈풙풙 [MPA] part’s manufacturing history in the FEM MIN - MAX MIN - MAX analysis, allowing the forecast of its true ABAQUS 0.0 13.51 -73.46 46.40 deformation limits.

STANDARD DIRECT 0.0 14.70 -760.13 293.58 5 Conclusions

Table 5 – Total deflection and stress in the This work allowed to increase accuracy of direction of loading, obtained in the Helius PFA the structural analysis of injection molded case study. components, establishing a set of methodologies

U [MM] 흈풙풙 [MPA] and definitions, as well as considering the part’s MIN - MAX MIN - MAX manufacturing history and the material STRAIN 0.03 6.56 -86.73 32.99 experimental data.

NO STRAIN 0.0 7.34 -72.65 23.86 The mesh aggregation during the injection simulation revealed to be crucial to overcome the The first approach (Abaqus Standard) mesh existing elements with high aspect ratio. shows that a structural analysis without This way, this work endorses the mesh quality as considering the part’s manufacturing effects, a major milestone to the accuracy of the final using only its undeformed shape and material results. properties, assumes a linear elastic behavior of The direct transfer method is the material, keeping its characteristics constant computationally very slow, that being a setback during the simulation. This case has reached the from the start. Additionally, this method reached smaller deformations, showing that the linear exaggerate levels of stress and strain, which relationship between the stress and strain fields is compromised its results accuracy. The biggest not enough to increase the analysis reliability. drawback of this method is the inability of The direct transfer model presents the implementing any material experimental data. greatest deflections and residual stresses. Thus, Helius PFA assumed to be the more the effect of the in cavity stress field, applied in accurate methodology of interaction between the first step of the analysis, overcharges the Abaqus and Moldflow. Beyond enabling the system with stress, warping prior to the implementation of the experimental tensile application of load and after it. It should be noted curves of the material, as well its mapping that this case also considers a linear elastic capability, this interface provides a set of tools behavior of the material, due to the inability of that optimize the reproduction of the implementing any experimental tensile curves in performance of an injection molded component. the structural analysis via direct transfer. Besides, the comparison between the results The third approach, using Helius PFA as an obtained by Helius and the material experimental interface between Abaqus and Moldflow, tensile curves showed a broad convergence, endorses the inclusion of the residual stress field endorsing the usage of this interface in order to as mean to implement the part´s manufacturing increase the structural analysis reliability. history in the structural analysis. The model

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