Prediction of damage in the hole-flanging process using a physically based approach

Abstract

The aim of this work is to identify the limits of the hole-flanging process experimentally and numerically by a physically based approach of damage for two different aluminium alloy sheets. Two hole-flanging conditions were considered, namely hole-flanging without ironing in which the flange is formed by edge stretching, and hole-flanging with ironing in which the metal is squeezed between the punch and the die. The forming defects were characterized experimentally by scanning electron microscope observations performed in critical zones of the flanged parts. The forming defects were also predicted numerically by a 3D finite element model based on Gurson-Tvergaard-Needleman constitutive equations. To evaluate the accuracy of the developed finite element model, material damage distribution within the workpiece during the process was studied and compared with experimental observations. Furthermore, the effects of the clearance-thickness ratio on the damage behaviour were investigated for different diameter of the initial hole. This study provides relevant and new results in the design of many parts obtained by holeflanging. Results showed that the model predicts accurately all types of failures (orange peel aspect, necking, microvoids, tear) for different conditions and both materials. Moreover, despite the large deformation induced by ironing, such conditions decrease the damage, due to void closure effects, that is in agreement with experimental results.

Identification strategy influence of elastoplastic behavior law parameters on Gurson–Tvergaard–Needleman damage parameters: Application to DP980 steel

“…Values below 0.5 are intentionally omitted since in this case nucleation parameter f N takes very high values compared to those known in the literature (Ayatollahi et al., 2016; Benseddiq and Imad, 2008; Kacem et al., 2014; Le Maoût et al., 2009; Liu et al., 2013; Mansouri et al., 2014; Masmoudi et al., 2017). In the case where α takes values greater than 0.7774, simulations produce results with a premature drop of the stress just before the necking area of the stress–strain curve.…”

“…(2014) where the authors use a fitting with three sections of the hardening curve. To identify the limits of the hole drilling process on two sheets of aluminum alloys, Kacem et al. (2014) applied the HS hardening law with a linear extension beyond the breaking point to describe the behavior of the alloy A1050-H14 and used the Voce-type law for alloy A6061-O.…”

“…(2016) used a smoothing for each part of three functions of the same type (Swift + Swift + Swift) and (Swift + Swift + linear function) and also used the curvature radius of the rational curve as appearance criterion of necking in high strength stainless steel tubes. The classical laws listed in Table 1, which have been modified (Cao et al., 2014; Kacem et al., 2014; Le Maoût et al., 2009; Masmoudi et al., 2017; Thuillier et al., 2010), have enabled the combination of the advantage of saturating laws (good representation of the stress–strain curve) with that of non-saturating laws (absence of premature force drop in the force–displacement curve). Indeed: A saturating law gives a good representation in the stress–strain curve but generates a premature force drop just before the necking area in the force–displacement curve. A non-saturating law gives a poor representation of the stress–strain curve without showing a premature force drop in the force–displacement curve.…”

A new fatigue damage accumulation model considering loading history and loading sequence based on damage equivalence

“…With the development and application of new technology and new theory, many new predicting methods are presented for the modern situation: probability prediction method (Grell and Laz, 2010; Larin and Vodka, 2015; Li et al., 2012; Ontiveros et al., 2010; Rathod et al., 2011; Xie et al., 2015); root mean square model (Kim et al. 2006); methodology using entropy index of stress interaction and crack severity index of effective stress (Kim et al., 2013); model for low-cycle fatigue life based on a partition of energy and micro-crack growth (Maurel et al., 2009); novel plane-stress continuum damage mechanics model (Lin et al., 2014); anisotropic damage model considering material degradation (Chow and Jie, 2009; Chow et al., 2007; Jie et al., 2011); multiaxial stress-based fatigue failure model (Liu et al., 2008, 2010); a new nonlinear continuum damage mechanics model for fatigue life prediction (Dattoma et al., 2006); fatigue driving stress approach (Kwofie and Rahbar, 2013); a reversal-by-reversal cumulative damage rule by using a new phenomenological technique (Huffman and Beckman, 2013); stochastic micromechanical damage model (Ju and Wu, 2016); physically based approach (Kacem et al., 2015); damage parameter method for creep damage prediction (Roy et al., 2015); dissipated energy-based calculation method (Gosar and Nagode, 2015); anisotropic gradient damage model based on microplane theory (Badnava et al., 2016); micromechanics-based incremental damage theory (Jiang et al., 2016); a new stress-based model for predicting ratcheting fatigue life (Mishra et al.,2016); strain range approach (Shen and Akanda et al., 2016); a new nonlinear ductile damage growth law based on the continuum thermodynamics (Kumar and Dixit, 2015); a new two-scale damage model (macro–meso) integrating a multiaxial fatigue criterion (Vu et al., 2014); a new method of material damage evaluation based on the X-ray computer tomography-detected microdefects and multiscale computer simulation (Shen et al., 2014); and so on.…”

Clonal fuzzy intelligent system for fault diagnosis of cracked beam

“…Pawar and Sawant (2014) have given the overview of vibration analysis of cracked cantilever beam with non-linear parameters and harmonic excitations. Various researchers have also made damage detection using different materials like Bhat and Ukadgaonker (2015) have examined a bi-material with crack, comprising elastic-plastic materials that are elastically identical but strength and plasticity mismatched and Kacem et al. (2015) have identified the limits of the hole-flanging process both experimentally and numerically by a physically based approach of damage for two different aluminum alloy sheets.…”