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

A method for measuring stress and strain distributions within a ductile material deforming by dislocational slip is developed. The method exploits the transparency and room-temperature ductility of silver chloride, and combines the techniques of photoelasticity and marker tracking. This method is used to investigate the deformation of an elasto-plastic ductile matrix surrounding an isolated stiff fiber, the grain size of the material being slightly smaller than the fiber length. The data are compared to predictions of finite element calculations which take the matrix to be an isotropic elasto-plastic von Mises continuum. It is found that this model does not fully capture all of the features of the experimental data. Data suggest that the cause for observed discrepancies is the strong influence exerted by grain boundaries and grain orientation on the distribution of stress and strain within the matrix. A comparison is also made between the data and predictions of the Eshelby equivalent inclusion calculation, to show that a far higher level of discrepancy results than with the finite element calculations; this is caused by the fact that the Eshelby equivalent inclusion calculation is essentially elastic and thus allows significant stress concentrations.