Tohoku University · Engineering
Professor Chrystelle Bernard's research lab specializes in the thermomechanical behavior and processing of advanced polymeric materials, with a focus on high-performance and semi-crystalline polymers. The lab investigates complex deformation mechanisms under large strains, strain rate effects, and microstructure evolution during forming and coating processes such as thermoforming and cold spraying. Key research directions include the development of accurate 3D constitutive models, experimental validation under multi-axial loading, and the optimization of processing parameters to enhance interfacial adhesion and material performance.
Figures are computed from collected data and may differ slightly.
In the present work, the thickness distribution in a plug-assisted thermoforming process is investigated using finite element (FE) simulations. Numerical simulations have been performed with the FE code ABAQUS/Explicit. The contact between sheet and tools is considered as isothermal. Moreover, the coefficient of friction between plug and sheet is assumed constant. The behavior of the material is described by three hyperelastic laws available in the FE code. The comparison between experimental an
High-performance polymer cold-spraying is attracting the interest of many for its economical, time-saving, and environmentally safe features in comparison to traditional thermal spraying processes. The cold spray process allows applying functional polymer coatings on a similar or dissimilar material surface for protective measures or additional functionalities. However, its practical use has been restricted by inherently low deposition efficiency associated with a weak interfacial adhesion stren
Numerous models have been developed in the literature to simulate the thermomechanical behavior of amorphous polymers at large strain. These models generally show a good agreement with experimental results when the material is submitted to uniaxial loadings (tension or compression) or in the case of shear loadings. However, this agreement is highly degraded when they are used in the case of combined load cases. A generalization of these models to more complex loads is scarce. In particular, mode
Navicular bones collected from the four limbs of 95 sound horses were studied. The anatomic bases have been laid down about morphometry of the navicular bones and their variations according to limbs, after corrections have been made for morphologic type, gender, weight, size and age. All the dimensions of the navicular bone (except for the thickness) were larger in the fore limb. This phenomenon probably reflects an attempt to compensate for the greater forces exerted upon the fore limbs during
Semi-crystalline polymers, and more particularly high molecular weight semi-crystalline polymers, exhibits interesting properties such as wear and impact resistance which contributes to their spreading into several industries and applications. However, because they have very long chains and exhibit high viscoelastic mechanical behavior, they are diffcult to process. It requires high temperature, close to melting temperature, and important compression strength to arrange the chains. However, such
Plasticized poly(vinyl chloride) (PPVC) is widely used in the automotive industry in the design of structural parts for crashworthiness applications. Thus, it is necessary to study and understand the influence of the mechanical response and mechanical properties of PPVC over a wide range of strain rate, from quasi-static to dynamic loadings. The process is also investigated using different sample thicknesses. In this work, the strain rate effect of a new PPVC is investigated over a wide range of
During the last decades, the part of polymeric materials considerably increased in automotive and packaging applications. However, their mechanical behaviour is difficult to predict due to a strong sensitivity to the strain rate and the temperature. Numerous theories and models were developed in order to understand and model their complex mechanical behaviour. The one proposed by Richeton et al. [Int. J. Solids Struct. 44, 7938 (2007)] seems particularly suitable since several material parameter
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