Analyses of strain localisation in hdpe butterfly specimen during biaxial tests using digital image correlation

This work presents a study of high density polyethylene (hdpe) strain under biaxial loading. An Arcan apparatus is achieved in order to load a newly-designed flat specimen called “butterfly specimen” to various combinations of tensile and shear loading.These specimens have a central region with a minimal thickness (1mm); witch constitutes a small area where the strain and the stress should be uniform before necking. All tests are conducted on an Instrone tensile machine at constant speed of the upper cross-head (v = 0,5 mm/min) at the ambient temperature. Displacement fields are measured in the central area of the specimens, during the tests, by coupling digital image correlation (DIC) with imaging using high-speed CCD cameras placed in front of the specimen. The experimental results show a strain localisation in the specimen gauge section

Analyses of strain localisation in hdpe butterfly specimen during biaxial tests using digital image correlation

This work presents a study of high density polyethylene (hdpe) strain under biaxial loading. An Arcan apparatus is achieved in order to load a newly-designed flat specimen called “butterfly specimen” to various combinations of tensile and shear loading.These specimens have a central region with a minimal thickness (1mm); witch constitutes a small area where the strain and the stress should be uniform before necking. All tests are conducted on an Instrone tensile machine at constant speed of the upper cross-head (v = 0,5 mm/min) at the ambient temperature. Displacement fields are measured in the central area of the specimens, during the tests, by coupling digital image correlation (DIC) with imaging using high-speed CCD cameras placed in front of the specimen. The experimental results show a strain localisation in the specimen gauge section

Modelling of thermal ageing effect on elastic-viscoplastic behaviour of semi-cristallin polymers by D.N.L.R approach

AbstractThis work is devoted to the numerical and experimental study of thermal ageing effect on microstructure and mechanical properties of HDPE. Uniaxiale tension tests were conducted at 25 0C in order to characterize the large deformation response of HDPE. The influence of thermal ageing on the alteration of the large deformation response of HDPE was examined. A Distribution of Non Linear Relaxation (D.N.L.R) Approach was used to describe the mechanical response of virgin HDPE. The thermal ageing effect was incorporated into the constitutive model to capture the stress-strain behaviour up to failure of aged HDPE. The model is shown to be in good agreement with experimental results

Experimental and numerical study of the mechanical behavior and kinetics of the martensitic transformation in 304L TRIP steel: applied to folding

International audienceIn this paper, experimental and phenomenological modeling of the mechanical behavior and austenite-martensitic transformation after deformation in 304L TRIP steel is investigated. Mechanical behavior and the evolution of the microstructure after folding test were studied 25 A degrees C. Scanning electron microscopy (SEM), Vickers hardness measurements, and X-ray diffraction test were conducted in order to characterize the deformation response and microstructure evolution of 304L TRIP steel. The analysis results indicate that both the microstructure and mechanical properties of the 304L TRIP steel varied gradually during the tests, the later showed too that the most favorable way for the formation of martensite is tension. Secondly, a phenomenological constitutive model, developed by Iwamoto et al., was selected and modified to include the microstructure evolution (austenite to martensite) after deformation. The validity and the limitation of the simulations are checked against the experimentally established stress-strain relation and the evolution of martensite phase. The simulation results show that the volume fraction of martensite is proportional to the strain and it is very important in the tended zone than the compressed zone. The results above present a foundation for the folding control technology

UV Aging Effects on Polycarbonate Properties

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