a b s t r a c tEdge fracture has been a well-known challenge in the forming processes of Advanced High Strength Steels (AHSS). The difficulty of the problem mainly lies in the complex loading path of out-of-plane shearing followed by in-plane stretching. Existing Finite Element models can not predict edge fracture with good accuracy. In the current study, two methods were implemented to tackle the problem for the DP780 steel sheet. The first method was a one-stroke FE simulation methodology making use of very fine solid elements of size of 0.01 mm in the critical region. After simulating the hole blanking process, a subsequent hole expansion simulation was continued with the same FE model. In other words, all material parameters were inherited from the sheet blanking process when performing the hole expansion simulation. Encouraged by the one-stroke simulation, a two-step phenomenological Pre-Damage Mapping Model (PDMM), was proposed and used in edge fracture prediction. This model performed the hole blanking simulation using a 2D axisymmetric model in step I. The mesh size used in step I was of order of 0.01 mm in the critical region. Then the model mapped/prescribed pre-damage and equivalent plastic strain (PEEQ) information obtained in step I in the vicinity of the hole edge to a solid element or shell element model with regular mesh size of order of 0.1 mm in step II. The results showed that both methods accurately predict edge fracture in terms of HER. The one-stroke simulation requires enormous computational power due to the very fine 3D solid element mesh, but it provides an accurate prediction of the detail distribution and orientation of cracks. The more simplified PDMM model gives a much quicker prediction of edge fracture and can be used in both solid element and shell element models, but loses some details captured by one-stroke simulation.
A numerical material model for intra-laminar failure prediction of biaxial Non Crimp Fabric composites is presented. The model combines the elasto-plastic continuum damage constitutive model proposed by Ladevèze with the intra-laminar matrix failure model of Puck, and improves the shear damage representation using an exponential damage function. The work focuses on numerical model development for damage and failure prediction and validation for both unsheared and sheared fabric composites which will result from draping of the fabric preform over a double curved geometry in order to manufacture complex shaped parts. An extensive test program has been conducted using flat composite coupons with differing degrees of fabric pre-shear in order to establish a database of material stiffness, strength, and in-plane matrix shear damage evolution prior to failure. This database is used to identify parameters for the proposed 'Ladevèze-Puck' damage and failure model. Final validation has been made by implementing the model in
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.