2015-08-13
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Напряженность и сжатие можно охарактеризовать следующими параметрами: деформации, напряжение и стресс. Стресс Стресс - интенсивность внутренних сил. Стресс выражается в силе на единицу площади (мегапаскалях, фунт сила на квадратный дюйм) и негативными для сжатия. Внешние силы причиной деформации членов. Деформации деформации - увеличение в оригинальном размере члена. Он измеряется в единицах длины.
Elongation
Elongation - the increase in gauge length of a body subjected to a tensile force, referenced to a gauge length on the body. The parameter is considered as strain.
Strain
Strain - deformation of member divided by the original length of member.
According to Hooke's law for elastic deformation, stress is proportional to strain. The ratio of elastic stress/strain is a constant of the material. This constant is known as Young's modulus or modulus of elasticity. This parameter has units of stress (MPa, GPa).
Polyethylene: E = 1 GPa = 1000 MPa
Glass: E = 60 GPa = 60 000 MPa
Aluminum: E = 73 GPa = 73 000 MPa
Steel: E = 207 GPa = 207 000 MPa
For the pressure vessel, the summed force in the bolts is equal to the sum of the force from inner pressures. This condition helps to find the necessary number of bolts n.
Long cables are very flexible, the primary source of deformation in the cables is axial.
There is a compressive stress in the base due to the weight of a heavy block and it's own weight. The figure shows the optimal shape of the base. For such a design, stresses in the bottom and at the top of the base are equal.
