scholarly journals Material Modeling of PMMA Film for Hot Embossing Process

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3398
Author(s):  
Dongwon Yun ◽  
Jong-Bong Kim
Keyword(s):  
Constitutive Model ◽  
Process Condition ◽  
Hot Embossing ◽  
Pmma Film ◽  
Arbitrary Lagrangian Eulerian ◽  
Softening Behavior ◽  
User Subroutine ◽  
Flexible Film ◽  
Precise Analysis ◽  
Fine Pattern

This study provides an analysis of the hot embossing process with poly methyl methacrylate (PMMA) film. The hot embossing process engraves a fine pattern on a flexible film using a stamp, applied heat and pressure. As the quality of the embossing pattern varies according to various process variables, the mechanism of making the embossed shape is complicated and difficult to analyze. Therefore, analysis takes much time and cost because it usually has to perform a lot of experiments to find an appropriate process condition. In this paper, the hot embossing process was analyzed using a computational analysis method to quickly find the optimal process. To do this, we analyzed the embossing phenomenon using the finite element method (FEM) and arbitrary Lagrangian–Eulerian (ALE) re-mesh technique. For this purpose, we developed a constitutive model considering the strain, strain rate, temperature-dependent stress and softening of the flexible film. Work hardening, strain softening, and temperature-softening behavior of PMMA materials were well described by the proposed method. The developed constitutive model were applied in the embossing analysis via user-subroutine. This proposed method allowed a precise analysis of the phenomenon of film change during the hot embossing process.

A Novel Approach for Thermomechanical Analysis of Stationary Rolling Tires within an ALE–Kinematic Framework

2013 ◽  
Vol 41 (3) ◽  
pp. 174-195 ◽  
Author(s):  
Anuwat Suwannachit ◽  
Udo Nackenhorst
Keyword(s):  
Constitutive Model ◽  
Numerical Solutions ◽  
Numerical Technique ◽  
Thermomechanical Analysis ◽  
Rolling Contact ◽  
Computational Technique ◽  
Heat Equations ◽  
Arbitrary Lagrangian Eulerian ◽  
Material Particle ◽  
Operator Split

ABSTRACT A new computational technique for the thermomechanical analysis of tires in stationary rolling contact is suggested. Different from the existing approaches, the proposed method uses the constitutive description of tire rubber components, such as large deformations, viscous hysteresis, dynamic stiffening, internal heating, and temperature dependency. A thermoviscoelastic constitutive model, which incorporates all the mentioned effects and their numerical aspects, is presented. An isentropic operator-split algorithm, which ensures numerical stability, was chosen for solving the coupled mechanical and energy balance equations. For the stationary rolling-contact analysis, the constitutive model presented and the operator-split algorithm are embedded into the Arbitrary Lagrangian Eulerian (ALE)–relative kinematic framework. The flow of material particles and their inelastic history within the spatially fixed mesh is described by using the recently developed numerical technique based on the Time Discontinuous Galerkin (TDG) method. For the efficient numerical solutions, a three-phase, staggered scheme is introduced. First, the nonlinear, mechanical subproblem is solved using inelastic constitutive equations. Next, deformations are transferred to the subsequent thermal phase for the solution of the heat equations concerning the internal dissipation as a source term. In the third step, the history of each material particle, i.e., each internal variable, is transported through the fixed mesh corresponding to the convective velocities. Finally, some numerical tests with an inelastic rubber wheel and a car tire model are presented.

Progressive Damage Approach to Simulating Low Velocity Impact Response of Plain Weave C/SiC Composites

2010 ◽  
Vol 118-120 ◽  
pp. 241-245 ◽  
Author(s):  
Liu Ding Chen ◽  
Xiao Yan Tong ◽  
Xiang Zheng ◽  
Lei Jiang Yao
Keyword(s):  
Constitutive Model ◽  
Time History ◽  
Composite Plates ◽  
Experimental Results ◽  
Low Velocity Impact ◽  
Progressive Damage ◽  
Low Velocity ◽  
Velocity Impact ◽  
Plain Weave ◽  
User Subroutine

Based on progressive damage theory, a 3D laminated model with an orthotropic property in plane was established to simulate the response of plain weave carbon fiber reinforced silicon carbide(C/SiC) ceramic matrix composites(CMC) under low velocity impact(LVI). Intra-layer damage and inter-layer damage were taken into account, respectively. Three scalar damage variables, associated with the degradation of warp modulus, weft modulus and shear modulus, respectively, were proposed to characterize intra-layer damage evolutions. The intra-layer constitutive model was implemented into MSC.Dytran, via its user subroutine EXFAIL1. The potential delamination region was considered as a discrete cohesive zone. Three vector spring elements were placed into every two adjacent nodes to simulate the inter-layer joints. A scalar damage variables, associated with the degradation of the three vector spring elements, were brought forward to characterize the inter-layer damage evolutions. The inter-layer constitutive model was implemented into MSC.Dytran, via its user subroutine EXELAS. Damage area, indentation depth of C/SiC composite plates and time history of impact force were obtained to compare with experimental results. The numerical results show overall good agreement with experimental results.

A Constitutive Model of Sandstone Considering the Post Peak Behavior

2017 ◽  
Vol 35 (1) ◽  
pp. 13-25 ◽  
Author(s):  
F. S. Jeng ◽  
M. C. Weng ◽  
F. H. Yeh ◽  
Y. H. Yang ◽  
T. H. Huang
Keyword(s):  
Constitutive Model ◽  
Nonlinear Elasticity ◽  
Strain Curve ◽  
Shear Loading ◽  
Triaxial Tests ◽  
Flow Rule ◽  
Plastic Behavior ◽  
Softening Behavior ◽  
Proposed Model ◽  
Confining Pressures

AbstractIn rock engineering, evaluating the post-peak strength and deformation of rock is necessary. To explore the elasto-plastic behavior of sandstone in the post-peak stage, a series of strain-controlled triaxial tests were conducted under different confining pressures. According to the post-peak characteristics, a constitutive model based on nonlinear elasticity and generalized plasticity is proposed. This proposed model is characterized by the following features: (1) Nonlinear elasticity is observed under hydrostatic and shear loading; (2) the associated flow rule is followed; (3) substantial plastic deformation occurs during shear loading; and (4) post-peak softening behavior is accurately predicted. This model requires twelve material parameters, three for elasticity and nine for plasticity. The proposed model was validated by comparing the triaxial test results of Mushan sandstone at different hydrostatic pressures under dry and saturated conditions. In addition, the model is versatile; it can simulate the deformational behavior of two other sandstones. In summary, the proposed model can reasonably predict the complete stress–strain curve of sandstone.

scholarly journals Modeling of Damage Evolution and Martensitic Transformation in Austenitic Steel at Cryogenic Temperature

2015 ◽  
Vol 62 (4) ◽  
pp. 523-537 ◽  
Author(s):  
Maciej Ryś
Keyword(s):  
Constitutive Model ◽  
Damage Evolution ◽  
Cryogenic Temperature ◽  
Tension Test ◽  
Transformation Kinetics ◽  
Structural Element ◽  
Finite Element Software ◽  
User Subroutine ◽  
Isotropic Damage ◽  
Cryogenic Conditions

Abstract In the present work, a constitutive model of materials undergoing the plastic strain induced phase transformation and damage evolution has been developed. The model is based on the linearized transformation kinetics. Moreover, isotropic damage evolution is considered. The constitutive model has been implemented in the finite element software Abaqus/Explicit by means of the external user subroutine VUMAT. A uniaxial tension test was simulated in Abaqus/Explicit to compare experimental and numerical results. Expansion bellows was also modelled and computed as a real structural element, commonly used at cryogenic conditions.

Study on Equivalent Constitutive Model and Optimization Design for Adapter of Submarine-Lunched Missile

2013 ◽  
Vol 753-755 ◽  
pp. 1391-1395
Author(s):  
Jian Guo Hu ◽  
Jie Zhao ◽  
Da Wei Ma
Keyword(s):  
Mechanical Property ◽  
Constitutive Model ◽  
Optimization Design ◽  
Mechanical Analysis ◽  
Good Effect ◽  
User Subroutine ◽  
Out Of Plane ◽  
Calculation Results ◽  
The Stability ◽  
Important Significance

V-shape adapter is one of the most used hollow adapter in submarine-lunched missile, studying on influence of mechanical property of adapter on submarine-launched performance has an important significance. Firstly, mechanical analysis on V-shape adapter is done and the equivalent out-of-plane mechanical property of adapter is obtained. Secondly, the equivalent constitutive model is built and the user subroutine VUMAT is developed based on ABAQUS/Explicit, while the stability and reliability of the calculation results are verified. According to the requirements of adapter performance from submarine-lunched missile, optimization design for adapter is carried out. The results show that the equivalent constitutive model can simplify the simulation of adapter and shorten the engineering time in research, and the optimized adapter can have a good effect on vibration reduction and supporting based on some relevant conditions.

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