# Stress

## Contents

# StressEdit

Read here about stress and tensegrity structures.

# Stress AnalysisEdit

Stress analysis is an engineering (e.g., civil engineering and mechanical engineering) discipline that determines the stress in materials and structures subjected to static or dynamic forces or loads. A stress analysis is required for the study and design of structures, e.g., tunnels, dams, mechanical parts, and structural frames among others, under prescribed or expected loads. Stress analysis may be applied as a design step to structures that do not yet exist.

The aim of the analysis is usually to determine whether the element or collection of elements, usually referred to as a structure, behaves as desired under the prescribed loading. For example, this might be achieved when the determined stress from the applied force(s) is less than the tensile yield strength or below the fatigue strength of the material.

Analysis may be performed through analytic mathematical modelling or computational simulation, through experimental testing techniques, or a combination of methods.

# Contrasting stress and linear deformationEdit

Levin published a critique of Xuan's animations, and wrote: The illustrations of Eddy Y. Xuan of Biomedical Communications, University of Toronto, Canada, on the Children’s Hospital, Boston’s website, misrepresent the effect of stress on tensegrities. His animations are true depictions of linear deformations, standard Poisson Ratio stuff, but that is not how tensegrity structures respond to stress. To quote Fuller, " … if concentrated load is applied from without, the whole system contracts symmetrically, i.e., all vertices move toward their common center at the same rate [Synergetics 724.32-34]."

Levin emphasizes that stress in tensegrity should cause global, and not local, deformation. Any contrary idea is engendered by using tensegrity models with rubber elastic tendons, which are poor at distributing the tension globally. Levin recommends mylar or nylon tendons for proper stress modelling.

# Links and ReferencesEdit

For more information see stiffness, shear, Finite Element Method.