scholarly journals MODELLING AND SIMULATION OF LATTICE STRUCTURES USING VARIOUS MATERIAL MODELS FOR POLYMERIC MATERIALS

2018 ◽  
Vol 18 ◽  
pp. 48
Author(s):  
Kerstin Lehner ◽  
Anna Kalteis ◽  
Zoltan Major
Keyword(s):  
Lightweight Design ◽  
Linear Thermal Expansion ◽  
Polymeric Materials ◽  
Mechanical Analysis ◽  
Elastic Behaviour ◽  
Material Models ◽  
Linear Elastic ◽  
Applied Loading ◽  
Hyper Elastic ◽  
Linear Elastic Behaviour

Based on lightweight design concepts, lattices are increasingly considered as internal structures. This work deals with the simulation of periodically constructed lattices to characterize their behaviour under different loadings considering various material models. A thermo-mechanical analysis was done, which is resulting in negative CLTE-values (Coefficient of Linear Thermal Expansion). Simulations with linear-elastic behaviour were evaluated regarding the tensile, compression and shear modulus and the Poisson’s ratio. Some of the investigated structures behave auxetic. Beside the linear elastic behaviour, also the hyper-elastic and visco-elastic behaviour of some structures were investigated. Furthermore, elasto-plastic simulations were performed where the applied loading was biaxial. As a result the initial yield surfaces were presented. The individual RVEs (Representative Volume Elements) can be utilized for different areas of application dependent on the used materials.

scholarly journals Extracting real-crack properties from non-linear elastic behaviour of rocks: abundance of cracks with dominating normal compliance and rocks with negative Poisson ratios

2017 ◽  
Vol 24 (3) ◽  
pp. 543-551 ◽  
Author(s):  
Vladimir Y. Zaitsev ◽  
Andrey V. Radostin ◽  
Elena Pasternak ◽  
Arcady Dyskin
Keyword(s):  
Experimental Data ◽  
Poisson Ratio ◽  
A Priori ◽  
Elastic Behaviour ◽  
Crack Model ◽  
Normal Compliance ◽  
S Wave ◽  
Linear Elastic ◽  
Non Linear ◽  
Linear Elastic Behaviour

Abstract. Results of examination of experimental data on non-linear elasticity of rocks using experimentally determined pressure dependences of P- and S-wave velocities from various literature sources are presented. Overall, over 90 rock samples are considered. Interpretation of the data is performed using an effective-medium description in which cracks are considered as compliant defects with explicitly introduced shear and normal compliances without specifying a particular crack model with an a priori given ratio of the compliances. Comparison with the experimental data indicated abundance (∼ 80 %) of cracks with the normal-to-shear compliance ratios that significantly exceed the values typical of conventionally used crack models (such as penny-shaped cuts or thin ellipsoidal cracks). Correspondingly, rocks with such cracks demonstrate a strongly decreased Poisson ratio including a significant (∼ 45 %) portion of rocks exhibiting negative Poisson ratios at lower pressures, for which the concentration of not yet closed cracks is maximal. The obtained results indicate the necessity for further development of crack models to account for the revealed numerous examples of cracks with strong domination of normal compliance. Discovering such a significant number of naturally auxetic rocks is in contrast to the conventional viewpoint that occurrence of a negative Poisson ratio is an exotic fact that is mostly discussed for artificial structures.

Numerical Modeling of Air Cushion Vehicle Flexible Fingers

2015 ◽  
Author(s):  
Robert E. Cole ◽  
Wayne L. Neu
Keyword(s):  
Research Effort ◽  
Prior Work ◽  
Fluid Structure Interactions ◽  
Elastic Materials ◽  
Material Models ◽  
Computational Tools ◽  
Linear Elastic ◽  
Hyper Elastic ◽  
Air Cushion ◽  
Air Cushion Vehicle

The goal of this research is to numerically model flexible finger seals of an air cushion vehicle (ACV) to more accurately predict resistance for these craft. Advancements in computational tools for fluid-structure interactions have set the stage for this effort. Prior work for this application has focused on planer type seals and not the finger type seals typical of modern ACVs. While this research effort remains underway and limited results are available, it is the authors’ desire to propose a pathway forward. Following the motivation and a brief review of prior work, verification of Abaqus/Explicit’s fluid solver is conducted using the analytical solution to Couette flow. Next, Abaqus/Standard (implicit scheme) is used to verify the finite element options for the structural portion. Various hyper elastic material models are also compared. Lastly, a FSI validation problem is conducted using Abaqus/Explicit for both linear elastic and hyper elastic materials.

Stress analysis of adhesive-bonded lap joints

1974 ◽  
Vol 9 (3) ◽  
pp. 185-196 ◽  
Author(s):  
R D Adams ◽  
N A Peppiatt
Keyword(s):  
Finite Element ◽  
Adhesive Layer ◽  
Lap Joints ◽  
Elastic Behaviour ◽  
Lap Joint ◽  
Linear Elastic ◽  
Rubber Model ◽  
Dimensional Finite Element ◽  
Linear Elastic Behaviour ◽  
Good Agreement

Stresses in a standard metal-to-metal adhesive-bonded lap joint are analysed by a two-dimensional finite-element method and comparisons are made with previous analyses. Particular attention is paid to the stresses at the ends of the adhesive layer. Unlike previous work, which assumes the adhesive to have a square edge, the adhesive spew is treated as a triangular fillet. The highest stresses exist at the adherend corner within the spew. Linear elastic behaviour is assumed throughout. A rubber model is reported which confirms these results physically. Good agreement was also obtained between some practical results and the finite-element predictions.

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