Detection of damage initiation and its evolution in insulating brick from non-linearity of stress/strain curve

This paper deals with experimental verification of the present author's theory relating to estimation of damage accumulation in materials showing non-linear stress/strain curves. The theory is based on parallel elements model and gives that the second order derivative of a stress/strain curve is proportional to a probability density function of strain at which each element is damaged. Uni-axial compression test was conducted for an insulating brick and its probability density function is obtained from the non-linear stress/strain curve. The function coincides well with acoustic emission data simultaneously measured in the compression test. This fact shows that the theory is useful for quick and brief estimation of damage initiation and its evolution in insulating bricks.