Under a given uni-axial mechanical stress , the flux density  for a given magnetizing field strength  may increase or decrease. The way in which a material responds to stresses depends on its saturation magnetostriction . For this analysis, compressive stresses  are considered as negative, whereas tensile stresses are positive.<br />
According to Le Chatelier's principle:
This means, that when the product  is positive, the flux density  increases under stress. On the other hand, when the product  is negative, the flux density  decreases under stress. This effect was confirmed experimentally.