Experimental investigation of stress and strain fields in a ductile matrix surrounding an elastic inclusion

摘要

A method for measuring stress and straindistributions within a ductile material deforming by dislocationalslip is developed. The method exploits the transparency and room-temperature ductility of silver chloride, and combines thetechniques of photoelasticity and marker tracking. This method isused to investigate the deformation of an elasto-plastic ductilematrix surrounding an isolated stiff fiber, the grain size of thematerial being slightly smaller than the fiber length. The data arecompared to predictions of finite element calculations which takethe matrix to be an isotropic elasto-plastic von Mites continuum. Itis found that this model does not fully capture all of the features ofthe experimental data. Data suggest that the cause for observeddiscrepancies is the strong influence exerted by grain boundariesand grain orientation on the distribution of stress and strain withinthe matrix. A comparison is also made between the data andpredictions of the Eshelby equivalent inclusion calculation, toshow that a far higher level of discrepancy results than with thefinite element calculations; this is caused by the fact that theEshelby equivalent inclusion calculation is essentially elastic andthus allows significant stress concentrations.