Abstract: The high pressure torsion (HPT) is an efficient process to obtain enhanced microstructures via super-plastic deformation. In view of its optimization, it is of prime importance to assess the relationships between processing conditions and material flow. More precisely, detailed knowledge of the plastic strain distribution in the deformed material in relation to HPT processing variables is very useful. In this context, the present work is focused primarily to highlight the effect of the temperature on the plastic strain distribution into the processed polymers by HPT. The effect of the sample thickness is also studied. To this end, the material parameters of an elastoviscoplastic phenomenological model were derived from compressive tests at different temperatures and strain rates on a typical thermoplastic polymer (high density polyethylene (HDPE)). The distribution of the equivalent plastic strain and the loading conditions were analysed. Recommendations on process conditions were proclaimed at the end of this work.

Keywords: HPT; HDPE; Finite element; Plastic strain; Temperature.

Abstract:The shape memory alloys (SMAs) are new materials with remarkable mechanical properties used in many structural technological areas of mechanics, aeronautics or biomechanics. The SMAs are considered to analyze the behavior of cupules of total hip prosthesis reprocessed in a block of polypropylene (PP) extruded in a solid state by using the process of extrusion cranked to equal areas (ECEA). In this work, definitions of SMAs, super elastic effect of shape memory alloys, their construction model and their applications in new technologies will be considered. A thermomechanical analysis estimation of their strain energy deformation absorption due to external loads has been studded. A predictive model of the behavior induced by simple mechanical stresses is then proposed. This behavior is broken down into two linear parts with two different elastic modules. This analytical modeling is built to be able to estimate the capacity of these alloys to absorb energy of deformation induced by a simple external loading. The Thermo-mechanical parameters of the SMA are determined experimentally. The results reveal differences in absorption of this energy level depending on the State in la when the alloy is located, i.e. martensitic or austenitic phase. The obtained results allowed us to determine the transformation temperatures of different of shape memory alloys materials in one hand, then their Young modules on the other, in order to validate the model of the constitutive behavior of stress deformation. The quantification of the capacity assessment of the SMA to absorb the energy of deformation is therefore essential in order to improve the performance of this material as well as to optimize the design of these types of smart materials.

Keywords: Shape memory allows; thermomechanics; strain energy; phase transformation; bending and internal forces.

Abstract: The interest of the present work which is firstly the mastery of mechanical behavior of plastic and metallic material to improve and optimize the mechanical characteristics of the different materials(ABS material, PVC material, PR material and P265GH steel material), another characterization approach was considered in this paper; it is a statistical study of Student that allows the selection of the most reliable results with a risk threshold of 10% for the both types of materials. On the other hand, a Weibull statistical study is carried out to extract the Weibull elements and subsequently define the reliability theory and damage of Weibull.

Keywords: Mechanics, material, weibull, science, releability.