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A separator is a membrane that prevents the physical contact between the positive and negative electrodes while enabling ionic transport. The integrity of the separator is vital to the performance and reliability of a battery. This paper presents finite element stress analysis for the separator in a lithium-ion battery using a macro-scale battery cell model. In this model, the porous electrodes were treated as homogenized media and represented with the effective properties estimated using the rule of mixtures. To compute the deformation due to lithium (Li) intercalation & deintercalation and temperature variation, the Li concentration distribution and temperature change due to electrochemical reactions must be known. These parameters were computed using a multi-physics model in COMSOL and mapped to the macro-scale model in ANSYS. Numerical simulations were conducted to identify the locations and magnitudes of the maximum strain and stress of the separator in the pouch cell.

The mechanical behavior of a commercially available single layer polypropylene (PP) separator was investigated using a dynamic mechanical analyzer (DMA). Samples were tested along the machine direction (MD) and transverse direction (TD). The tensile stress-strain, tensile creep and viscoelastic behaviors were studied. Experiments were performed in two conditions: (1) dry and (2) wet, i.e., samples submersed in dimethyl carbonate (DMC). The experimental results revealed that the mechanical properties of the separator were much lower while being submersed in DMC. This finding suggests that the mechanical properties measured at a dry condition may not be sufficient to represent the in-situ material behavior. Therefore, it is important to conduct material characterization in an environment close to the service condition.

This paper investigates the impact deformation and fracture of a co-extruded multi-layer polymeric material. The material consists of a layer of ethylene vinyl alcohol, EvOH, two layers of linear low density polyethylene (LLDPE) based adhesive and three layers of high density polyethylene (HDPE). The multi-layer material was driven dart impact tested with velocities of 0.4 m/sec and 4.0 m/sec at 23°C and -40°C temperature conditions. The fracture morphology of the material was studied using scanning electron microscopic (SEM). An increase in energy absorption up to the maximum load was observed at -40°C; whereas, the total energy absorption decreased when compared to those tested at ambient temperature conditions. SEM observation revealed that the EvOH layer was the major contributor to the reduced ductility of the multi-layer system.

This paper presents a methodology for practical estimation of the cutting force and cutting power. Providing a complete list of mathematical expressions needed for the calculation, the paper demonstrates their utility for turning operation of two work materials: AISI bearing steel E52100 and aerospace aluminum alloy 2024 T6. The calculated cutting forces are in good agreement with the experimental results. Energy partition in the cutting system and relative impact of the parameters of the machining regime are discussed. For the first time, a simple practical method is available for the calculation of the total cutting power and the cutting force.

To consider the variation of the joint strength on crashworthiness performance of the vehicles, one needs to model the adhesive fracture and/or adhesive bonded joint separation in explicit FE simulations. This paper examines an adhesive material model, MAT169, in LS-DYNA and its capability in modeling of adhesively bonded joints. Initial investigations were conducted on aluminum/epoxy joints including single lap shear, scarf and double cantilever joints. The results show that MAT169 actually is a cohesive interface element implemented in the form of a solid element. MAT169 is computationally efficient and can be used in a production environment. The result of this study is also applicable to adhesively bonded joints with other substrates including composites, steel and hybrid materials.

Laminated steel has been increasingly applied in automotive products for vibration and noise reduction. One of the major challenges the laminated steel poses is how to simulate forming processes and predict formability severity with acceptable correlation in production environment, which is caused by the fact that a thin polymer core possesses mechanical properties with significant difference in comparison with that of steel skins. In this study a cantilever beam test is conducted for investigating flexural behavior of the laminated steel and a finite element modeling technique is proposed for forming simulation of the laminated steel. Two production panels are analyzed for formability prediction and the results are compared with those from the try-out for validation. This procedure demonstrates that the prediction and try-out are in good agreement for both panels.

This paper examines the effect of rate dependence of material parameters on FMVSS 201 simulation using LS-DYNA with the exiting elasto-plastic material models and user subroutines. The material parameters investigated include the yield stress, Young's modulus and failure strain. The effect of yield criterion is also discussed.