scholarly journals Modeling the mechanical properties of ultra-thin polymer films

2017 ◽  
Vol 5 ◽  
Author(s):  
Francisco Espinosa-Loza ◽  
Michael Stadermann ◽  
Chantel Aracne-Ruddle ◽  
Rebecca Casey ◽  
Philip Miller ◽  
...  
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Material Model ◽  
Constitutive Material Model ◽  
Element Simulation ◽  
Thin Polymer ◽  
Experimental Parameters ◽  
Constitutive Material ◽  
Analytical Approaches ◽  
The Relationship

A modeling method to extract the mechanical properties of ultra-thin films (10–100 nm thick) from experimental data generated by indentation of freestanding circular films using a spherical indenter is presented. The relationship between the mechanical properties of the film and experimental parameters including load, and deflection are discussed in the context of a constitutive material model, test variables, and analytical approaches. Elastic and plastic regimes are identified by comparison of finite element simulation and experimental data.

scholarly journals Identification of the LLDPE Constitutive Material Model for Energy Absorption in Impact Applications

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1537
Author(s):  
Luděk Hynčík ◽  
Petra Kochová ◽  
Jan Špička ◽  
Tomasz Bońkowski ◽  
Robert Cimrman ◽  
...  
Keyword(s):  
Strain Rate ◽  
Material Model ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Stress Strain ◽  
Rate Dependent ◽  
Constitutive Material Model ◽  
Principal Directions ◽  
Constitutive Material

Current industrial trends bring new challenges in energy absorbing systems. Polymer materials as the traditional packaging materials seem to be promising due to their low weight, structure, and production price. Based on the review, the linear low-density polyethylene (LLDPE) material was identified as the most promising material for absorbing impact energy. The current paper addresses the identification of the material parameters and the development of a constitutive material model to be used in future designs by virtual prototyping. The paper deals with the experimental measurement of the stress-strain relations of linear low-density polyethylene under static and dynamic loading. The quasi-static measurement was realized in two perpendicular principal directions and was supplemented by a test measurement in the 45° direction, i.e., exactly between the principal directions. The quasi-static stress-strain curves were analyzed as an initial step for dynamic strain rate-dependent material behavior. The dynamic response was tested in a drop tower using a spherical impactor hitting a flat material multi-layered specimen at two different energy levels. The strain rate-dependent material model was identified by optimizing the static material response obtained in the dynamic experiments. The material model was validated by the virtual reconstruction of the experiments and by comparing the numerical results to the experimental ones.

scholarly journals Study on modified Johnson-Cook constitutive material model to predict the dynamic behavior Mg-1Al-4Y alloy

2020 ◽  
Vol 7 (2) ◽  
pp. 026522
Author(s):  
Jinhui Wang ◽  
Xiaoguang Yuan ◽  
Peipeng Jin ◽  
Hongbin Ma ◽  
Bo Shi ◽  
...  
Keyword(s):  
Dynamic Behavior ◽  
Material Model ◽  
Constitutive Material Model ◽  
Constitutive Material

Accurate Prediction of Springback in Forming of BIW Parts

2012 ◽  
Vol 165 ◽  
pp. 93-97
Author(s):  
Nagur Aziz Kamal Bashah ◽  
Ahmad Zakaria ◽  
Khairul Za’im Kamarulzaman ◽  
Achmed Mobin ◽  
Mohd Safuan Mohd Abdul Lazat ◽  
...  
Keyword(s):  
Neural Network ◽  
High Strength Steels ◽  
High Strength ◽  
Material Model ◽  
Part Geometry ◽  
Constitutive Material Model ◽  
The Neural Network ◽  
Automotive Parts ◽  
Constitutive Material ◽  
Different Levels

The use of High Strength Steels (HSS) for automotive parts improves car performance in terms of structural strength and weight reduction. However it poses major challenges to manufacturing since HSS is prone to springback. Springback causes deviation in part geometry from its intended design thus giving problem to its subsequent assembly process. In this paper, three models for predicting springback were evaluated. First model is based on the Multiple Regression (MR) technique. Second model utilized Hill Orthotropic constitutive material model and the last model employed a neural network predictive model. All the models were evaluated by using tool surface and stamped part historical data that are obtained from three selected springback prone automotive BIW parts representing three different levels of springback severity namely high, medium and small. The results on the low springback part show that the neural network model outperforms the other approaches.

Use of Digital Image Correlation to Track Strain Evolution in Compressed Masonry Piers

2015 ◽  
Vol 732 ◽  
pp. 337-340
Author(s):  
Jakub Antoš ◽  
Václav Nežerka ◽  
Pavel Tesárek
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Strain Localization ◽  
Material Model ◽  
Element Model ◽  
Image Correlation ◽  
Full Field ◽  
Constitutive Material Model ◽  
The Cost ◽  
Constitutive Material

In order to develop a constitutive material model and to verify its consistency when implemented in a computational code, it is necessary to understand the material and to carry out a comprehensive experimental analysis. This can be a challenging task in the case of composite materials and structures, such as masonry, when using conventional measurements. Strain gauges and allow recording strains at a limited number of discrete points and do not provide sufficient amount of data, thus increasing the cost of the analysis. From that reason a full-field non-contact measurements, such as Digital Image Correlation (DIC), became very popular and valuable for analysis of structures subjected to mechanical loading and precise detection of the onset of strain localization. The presented study deals with tracking the strain localization using DIC in the case of masonry piers loaded by the combination of bending and compression. In such case the strain localizes into more compliant mortar joints while the complete collapse occurs when the masonry blocks fail to transfer tensile stress due to transversal expansion. The obtained data will be used for the validation of a finite element model to predict the behavior of masonry structures.

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