Modeling the large inelastic deformation response of non-filled and silica filled SL5170 cured resin

In recent years, important efforts have been focused on rapid production of tools using Rapid Prototyping and Manufacturing (RP&M) technologies such as the Stereo-Lithography Apparatus (SLA). One of the applications is the development of rapid polymer tooling such as dies for injection molding. For these applications, optimal thermal as well as mechanical properties of final tools are of significance. In order to characterize the mechanical response of materials made by SLA, a standard set of material tests, including uniaxial tension and compression tests under different strain rates and different temperatures, was conducted for both silica filled and non-filled resin. In this paper, the mechanical response of the non-filled SL5170 cured resin is discussed in terms of an elastic-viscoplastic material model. Further, a new model for silica filled SL5170 cured resin was developed to estimate the stress-strain relationship of the composite. This composite model is an extension of the elastic-viscoplastic model for non-filled resin to include the elastic deformation of the silica particles. The stress-strain curves predicted by the models under homogeneous deformation show good agreement with the experimental results.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44781/1/10853_2005_Article_903.pd

Modeling of dynamic failure by nucleation and growth processes

It is well established that high rate failure of structural materials takes place by rate processes occurring at the micro level and involving nucleation, growth, and coalescence of voids or cracks. At the submicroscopic level, the mechanism of failure in materials is dislocation controlled. The process of deformation and failure can be described by plastic glide that involves the mechanism of dislocation pile-ups. A new physically based model describing these processes is proposed. The effects of inertia and rate sensitivity on the growth process, and porosity are examined. The model formulation is three-dimensional and is suitable for a general state of stress and strain. The model constants are calibrated through numerical simulations of one dimensional strain based plate impact experiments. To demonstrate the generality of model to predict spall under multiaxial loading conditions, an experimental configuration in which a flyer plate impacts the base of a solid right circular cone has been simulated. The computational modeling has been performed with thermomechanical coupling. The mechanical threshold stress plasticity model, the new proposed failure model, and the equation of heat conduction have been implemented in the finite element code Abaqus. Results from these simulations are presented and discussed in comparison with the experimental results. This shows the capability of the model in matching the experimentally observed spall patterns in the solid cone

Numerical study of deformation textures, yield locus, rolling components and Lankford coefficients for FCC polycrystals using the new polycrystalline φ-model

In this paper, we discuss results from the new viscoplastic non-linear intermediate ϕ-model for crystal plasticity. We used this viscoplastic ϕ-model in order to compute several properties and indicators directly connected to the formability of FCC polycrystalline metals. For instance, the yield locus, the Lankford coefficients and the typical FCC rolling texture component and their evolution during plastic deformation are computed. We also compare our results to those predicted by the tangent viscoplastic self-consistent model as well as those obtained by the upper and lower bounds (Taylor and Static). Results concerning FCC metals subjected to plane strain compression (commonly used for the approximation of the rolling process) are presented. As in the self-consistent scheme, the viscoplastic ϕ-model takes into account the strength of grains interactions. The influence of the grain interaction on predicted results is discussed. This analysis of the change in predicted results for different values of the parameter controlling the grain interaction strength (from a stiff to a more compliant interaction) shows that the results depend strongly on ϕ

Rolling texture transition in FCC metals using the viscoplastic φ -model and considering mechanical twinning

The viscoplastic Φ-model belongs to the same class of self-consistent models but it is based on a new theory without the Eshelby scheme. The Φ-model, by varying the parameter Φ, can predict a very large range of the texture components: from the lower (Φ →1) to the upper (Φ→0 ) bounds results. In this work, we adapt the Φ-model to take into account the mechanical twinning. This extended Φ-model is used to predict textures in FCC metals under plane strain compression test. We show that the deformation twinning plays an important role in the formation of brass-type texture

High-speed blanking of copper alloy sheets: Material modeling and simulation

To optimize the blanking process of thin copper sheets ($\approx$1. mm thickness), it is necessary to study the influence of the process parameters such as the punch-die clearance and the wear of the punch and the die. For high stroke rates, the strain rate developed in the work-piece can be very high. Therefore, the material modeling must include the dynamic effects.For the modeling part, we propose an elastic-viscoplastic material model combined with a non-linear isotropic damage evolution law based on the theory of the continuum damage mechanics. Our proposed modeling is valid for a wide range of strain rates and temperatures. Finite Element simulations, using the commercial code ABAQUS/Explicit, of the blanking process are then conducted and the results are compared to the experimental investigations. The predicted cut edge of the blanked part and the punch-force displacement curves are discussed as function of the process parameters. The evolution of the shape errors (roll-over depth, fracture depth, shearing depth, and burr formation) as function of the punch-die clearance, the punch and the die wear, and the contact punch/die/blank-holder are presented. A discussion on the different stages of the blanking process as function of the processing parameters is given. The predicted results of the blanking dependence on strain-rate and temperature using our modeling are presented (for the plasticity and damage). The comparison our model results with the experimental ones shows a good agreement

Travail des alliages de cuivre en feuilles : simulation et optimisation numérique 2D du procédé de découpe

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Modeling and simulation of dynamic failure in metal

Non renseign

A new three-phase model to estimate the effective elastic properties of semi-crystalline polymers: Application to PET

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