Implementation of Exponential Function for Isotropic Hardening of Metallic Foams

Porous material such as metal foams have found wideapplications in industry due to their useful propertiessuch as low density, high hardness, thermal and acousticinsulation and high permeability to gas. These materialsare used for the production of light weight structuresbecause of the low density. Due to their high energyabsorption properties of porous materials incompression stress, metallic foams can be substitutewith previous structures have been used before. Themajor applications of porous materials are in aerospaceand automotive industries. Foams are widely used inindustry, so prediction of their behaviour is veryimportant. In recent years, extensive researches havebeen done on the behaviour of these materials and so farseveral constitutive equations are presented for foams.The strain behaviour of foam in constitutive equation, isspecified by the work hardening function. There are twotypes of work hardening: isotropic hardening andkinematic hardening. In ۲۰۰۰, Deshpande and Fleckoffered a constitutive equation with isotropic hardening.A new constitutive equation for isotropic hardeningfoam is provided in this study which includes ۳parameters.This equation is integrated using return mappingalgorithm and developing a numerical code inMATLAB. Then coefficients of constitutive equationare determined using genetic algorithm and theexperimental and numerical results have beencompared. Four types of aluminum foams have beenstudied in this investigation including Alporas,Foaminal, Alulight and Cymat that are commerciallyavailable. Comparison between numerical results andexperimental data shows that this new equation is ableto predict the behaviour of foams with acceptableaccuracy and there is good agreement betweennumerical and experimental results.

کلیدواژه ها:

Aluminum foam ، Isotropic hardening ، Returnmapping algorithm ، Genetic algorithm