The strains occurring in three orthogonal directions can give us a measure of a material's dilation in response to multiaxial loading. This occurs due to a material property known as Poisson's ratio – the ratio between lateral and axial strains. In particular, we learned that stress in one direction causes deformation in three directions. they follow Hooke's law) and isotropic (they behave the same no matter which direction you pull on them).Īdditionally, we learned about multiaxial loading in this section. In this course, we will focus only on materials that are linear elastic (i.e. For most engineering materials, the linear region of the stress-strain diagram only occurs for very small strains (<0.1%). This value can vary greatly from 1 kPa for Jello to 100 GPa for steel. If you plot stress versus strain, for small strains this graph will be linear, and the slope of the line will be a property of the material known as Young's Elastic Modulus. This linear, elastic relationship between stress and strain is known as Hooke's Law. In the simplest case, the more you pull on an object, the more it deforms, and for small values of strain this relationship is linear. This measurement can be done using a tensile test. Stress and strain are related by a constitutive law, and we can determine their relationship experimentally by measuring how much stress is required to stretch a material.
