File Name: the geometry of stress and strain .zip
The Stress Tensor
Many physical properties of crystalline materials are direction dependent because the arrangement of the atoms in the crystal lattice are different in different directions. If one heats a block of glass it will expand by the same amount in each direction, but the expansion of a crystal will differ depending on whether one is measuring parallel to the a-axis or the b-axis. For this reason properties such as the elasticity and thermal expansivity cannot be expressed as scalars. We use tensors as a tool to deal with more this complex situation and because single crystal properties are important for understanding the bulk behavior of rocks and Earth , we wind up dealing with tensors fairly often in mineral physics. A tensor is a multi-dimensional array of numerical values that can be used to describe the physical state or properties of a material.
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Stress is plotted on the Y-Axis and Strain is plotted on the X-axis. In material science and mechanical engineering, the stress-strain curve is widely used to understand the strength, deformation, and failure criteria of any material. In this article, we will explore details about the stress-strain curve. In that instrument, a force on the standard specimen is increased till its failure and a plotter keeps recording the stress and strain. The Yield Strength of a material is the maximum stress after which the elongation becomes plastic and permanent deformation starts. Once the yield strength of a material is reached, large deformation occurs with very little increase in the applied load.
Strength of materials , also called mechanics of materials , is a subject which deals with the behavior of solid objects subject to stresses and strains. In materials science, the strength of a material is its ability to withstand an applied load without failure. A load applied to a mechanical member will induce internal forces within the member called stresses when those forces are expressed on a unit basis. The stresses acting on the material cause deformation of the material in various manner. Deformation of the material is called strain when those deformations too are placed on a unit basis. The applied loads may be axial tensile or compressive , or shear.
Strain and Stress
In continuum mechanics , stress is a physical quantity that expresses the internal forces that neighbouring particles of a continuous material exert on each other, while strain is the measure of the deformation of the material. For example, when a solid vertical bar is supporting an overhead weight , each particle in the bar pushes on the particles immediately below it. When a liquid is in a closed container under pressure , each particle gets pushed against by all the surrounding particles.
THE first and foremost problem in aircraft production is one of proper design and rapid production of sheet metal forming tools. A full understanding of forming properties of various aircraft materials, the limits of each method of forming, and die design and construction, are of vital importance to every tool designer and tool planner. The problems of production, particularly forming problems, will be greatly simplified by the use of this same knowledge and information in the design of sheet metal parts.