scholarly journals Reliability of Free Inflation and Dynamic Mechanics Tests on the Prediction of the Behavior of the Polymethylsilsesquioxane–High-Density Polyethylene Nanocomposite for Thermoforming Applications

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2753
Author(s):  
Fouad Erchiqui ◽  
Khaled Zaafrane ◽  
Abdessamad Baatti ◽  
Hamid Kaddami ◽  
Abdellatif Imad
Keyword(s):  
Finite Element Method ◽  
High Density Polyethylene ◽  
Numerical Study ◽  
Viscoelastic Behavior ◽  
High Density ◽  
The Finite Element Method ◽  
Precise Knowledge ◽  
Least Squares Optimization ◽  
Dynamic Mechanical Testing ◽  
Thermoforming Process

Numerical modeling of the thermoforming process of polymeric sheets requires precise knowledge of the viscoelastic behavior under conjugate effect pressure and temperature. Using two different experiments, bubble inflation and dynamic mechanical testing on a high-density polyethylene (HDPE) nanocomposite reinforced with polymethylsilsesquioxane HDPE (PMSQ–HDPE) nanoparticles, material constants for Christensen’s model were determined by the least squares optimization. The viscoelastic identification relative to the inflation test seemed to be the most appropriate for the numerical study of thermoforming of a thin PMSQ–HDPE part. For this purpose, the finite element method was considered.

scholarly journals Influence of Retardation Time on Viscoelastic Behavior of Plane Beams Modeled by the Nonlinear Positional Formulation of the Finite Element Method

2021 ◽  
Vol 2021 ◽  
pp. 1-22
Author(s):  
Juliano dos Santos Becho ◽  
Marcelo Greco
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Rheological Model ◽  
Iterative Process ◽  
Numerical Procedure ◽  
Viscoelastic Behavior ◽  
Retardation Time ◽  
The Finite Element Method ◽  
Divergence Problem ◽  
Element Method

A numerical procedure is presented to avoid the divergence problem during the iterative process in viscoelastic analyses. This problem is observed when the positional formulation of the finite element method is adopted in association with the finite difference method. To do this, the nonlinear positional formulation is presented considering plane frame elements with Bernoulli–Euler kinematics and viscoelastic behavior. The considered geometrical nonlinearity refers to the structural equilibrium analysis in the deformed position using the Newton–Raphson iterative method. However, the considered physical nonlinearity refers to the description of the viscoelastic behavior through the adoption of the stress-strain relation based on the Kelvin–Voigt rheological model. After the presentation of the formulation, a detailed analysis of the divergence problem in the iterative process is performed. Then, an original numerical procedure is presented to avoid the divergence problem based on the retardation time of the adopted rheological model and the penalization of the nodal position correction vector. Based on the developments and the obtained results, it is possible to conclude that the presented formulation is consistent and that the proposed procedure allows for obtaining the equilibrium positions for any time step value adopted without presenting divergence problems during the iterative process and without changing the analysis of the final results.

Analysis of Aerodynamic Journal Bearings With Small Number of Herringbone Grooves by Finite Element Method

1994 ◽  
Vol 116 (4) ◽  
pp. 698-704 ◽  
Author(s):  
D. Bonneau ◽  
J. Absi
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Study ◽  
Load Capacity ◽  
Journal Bearings ◽  
The Finite Element Method ◽  
Bearing Number ◽  
Comparison Of The Results ◽  
Herringbone Grooves ◽  
Element Method

A numerical study of gas herringbone grooved journal bearings is presented for small number of grooves. The compressible Reynolds equation is solved by use of the Finite Element Method. The nonlinearity of the discretized equations is treated with the Newton-Raphson procedure. A comparison of the results for a smooth bearing with previously published results is made and the domain of validity of the Narrow Groove Theory is analyzed. Load capacity, attitude angle, and stiffness coefficients are given for various configurations: groove angle and thickness of grooves, bearing number, and that for both smooth and grooved member rotating.

scholarly journals NUMERICAL STUDY ON EFFECTS OF TENON SIZES ON WITHDRAWAL LOAD CAPACITY OF MORTISE AND TENON JOINT

Wood Research ◽  
2021 ◽  
Vol 66 (2) ◽  
pp. 321-330
Author(s):  
Tianxing Zhang ◽  
Wengang Hu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Response Surface ◽  
Numerical Study ◽  
Load Capacity ◽  
The Finite Element Method ◽  
Surface Method ◽  
Mortise And Tenon ◽  
Relationship Of ◽  
The Relationship

The effect of tenon length and tenon width on withdrawal load capacity of mortise and tenon (M-T) joint was studied based on the finite element method (FEM), and the relationship of withdrawal load capacity relating to tenon length and tenon width was regressed using response surface method. The results showed that the tenon length and tenon width had remarkable effects on withdrawal load capacity of M-T joint T-shaped sample. The effect of tenon length on withdrawal load capacity was greater than tenon width. The regression equation used to predict the withdrawal load capacity was capable of optimizing the tenon sizes of M-T joint with R-square of 0.926. Using FEM can get more knowledge of M-T joint visually, and reduce the costs of materials and time of experiments.

An analytical approach to evaluate effective coefficients of 1–3 piezoelectric composites

2021 ◽  
Author(s):  
Sanjeev Kumar Singh ◽  
Saroja Kanta Panda
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Volume Fraction ◽  
Numerical Study ◽  
The Finite Element Method ◽  
Effective Coefficients ◽  
Square Packing ◽  
Packing Arrangement ◽  
Piezoelectric Fiber ◽  
Element Method

In this paper, a micromechanics method is developed to evaluate effective coefficients of piezoelectric fiber-reinforced composites. An exact solution is derived for effective elastic, piezoelectric and dielectric coefficients of such piezocomposites subjected to the applied load in the direction transverse to the fiber orientation. Simultaneously, based on finite element method, a numerical study is performed on a representative volume element of such piezo composite containing fiber in square packing arrangement. The finite element method provides a numerical solution to evaluate effective elastic, piezoelectric and dielectric coefficients for discrete volume fraction of fiber, the range being 0.1–0.6 for this study. The results are interpolated to understand the overall behavior of such piezocomposites. The results obtained from the micromechanics method and the finite element method are compared with the results obtained from other models based on strength of materials method given in the literature. It is observed that the method developed in this study provides better results for effective coefficients susceptible to fiber packing arrangements.

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