Structural integrity and failure
Structural integrity and failure is an aspect of engineering that deals with the ability of a structure to support a designed structural load without breaking and includes the study of past structural failures in order to prevent failures in future designs.
Collapsed barn at Hörsne, Gotland, Sweden
The Pyramid at Meidum was the second built by the Egyptians around 2600 BC. It suffered from many structural defects, causing it to collapse during construction and leaving the inner core standing in a pile of rubble, which provided one of the earliest known lessons in large-scale building.
Building collapse due to snow weight
The Dee bridge after its collapse
Deformation (engineering)
In engineering, deformation refers to the change in size or shape of an object. Displacements are the absolute change in position of a point on the object. Deflection is the relative change in external displacements on an object. Strain is the relative internal change in shape of an infinitesimal cube of material and can be expressed as a non-dimensional change in length or angle of distortion of the cube. Strains are related to the forces acting on the cube, which are known as stress, by a stress-strain curve. The relationship between stress and strain is generally linear and reversible up until the yield point and the deformation is elastic. Elasticity in materials occurs when applied stress does not surpass the energy required to break molecular bonds, allowing the material to deform reversibly and return to its original shape once the stress is removed. The linear relationship for a material is known as Young's modulus. Above the yield point, some degree of permanent distortion remains after unloading and is termed plastic deformation. The determination of the stress and strain throughout a solid object is given by the field of strength of materials and for a structure by structural analysis.
Considere Plot. (a) True stress-strain curve without tangents. There is neither necking nor drawing. (b) With one tangent. There is only necking. (c) With two tangents. There are both necking and drawing.