Failure analysis based on microvoid growth for sheet metal during uniaxial and biaxial tensile tests

Abstract

. Failure analysis based on microvoid growth for sheet metal during uniaxial and biaxial tensile tests. Materials and Design, Elsevier, 2013, vol. 49, pp. 638-646. <10.1016/j.matdes.2013 OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. a b s t r a c tThe aim of the presented investigations is to perform an analysis of fracture and instability during simple and complex load testing by addressing the influence of ductile damage evolution in necking processes. In this context, an improved experimental methodology was developed and successfully used to evaluate localization of deformation during uniaxial and biaxial tensile tests. The biaxial tensile tests are carried out using cruciform specimen loaded using a biaxial testing machine. In this experimental investigation, Stereo-Image Correlation technique has is used to produce the heterogeneous deformations map within the specimen surface. Scanning electron microscope is used to evaluate the fracture mechanism and the micro-voids growth. A finite element model of uniaxial and biaxial tensile tests are developed, where a ductile damage model Gurson-Tvergaard-Needleman (GTN) is used to describe material deformation involving damage evolution. Comparison between the experimental and the simulation results show the accuracy of the finite element model to predict the instability phenomenon. The advanced measurement techniques contribute to understand better the ductile fracture mechanism.

On the connection between microstructure and surface roughness of brass sheets and their formability

“…The concentration of strain within the groove eventually leads to the plane strain conditions within the groove and localized necking. In many calculations, the imperfection parameter f which was defined as the ratio of the sheet thickness in the groove to sheet thickness outside the groove, was chosen arbitrary or for the best fit of calculations with experimental results of the limit strains [1,9,20]. The M-K model can be readily adopted to represent the influence of different kinds of material inhomogeneity provided that the assumption that the weak region in the form of a long band is retained.…”

EVALUATION OF FORMABILITY OF THIN SHEETS BASED ON Al-Mg-Si FOR AUTOMOTIVE INDUSTRY

“…Black stochastic spotted image was created using a special graphite-spray on a white background. The authors [23,24] developed a methodology of software ARAMIS. The Table 2 shows calculated values of surface anisotropy for two different orientations relative to the direction of 0°.…”

Path independent limiting criteria in sheet metal forming

“…Stress triaxiality (Á), the ratio of hydrostatic/mean stress ( m ) to equivalent stress ( eq ) is widely used as a conventional damage parameter in many classical damage models like Gurson-Tvergaard-Needleman (GTN) model for ductile damage [28], Pirondi and Bonora (PB) continuum damage mechanics (CDM) model [29], Johnson-Cook fracture model (JC) [30] etc. Xue-Wierzbicki model (XW) [31,32] has related the locus of fracture equivalent strain to stress triaxiality and load angle parameter.…”