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Cylindrical rod

QuickField simulation example

Cylindrical rod is loaded by tensile forces.

Problem Type
Axisymmetric problem of stress analysis.

Geometry
Cylindrical rod is loaded by tensile forces Calculate bar elongation, the decrease in diameter and the increase in volume P=85 kN P=85 kN Aluminum alloy Ø30 mm L = 3000 mm

Given
Rod's length L=3000 mm, cross-section diameter d = 30 mm;
Young's modulus of the aluminum alloy E = 70 GPa;
Poisson's coefficient of the aluminum alloy ν = 1/3;
Force P = 85 kN.

Task
Calculate bar elongation, the decrease in diameter and the increase in volume.

Solution
One of the rod's ends is fixed. The other end is loaded by the tensile force fz = P / S,
where S= 786·10-6 [m²] - is the rod cross-section area.

Volume change can be calculated by the length dL and width dr increments:
dV = (L+dL)·π·(R+dr)² - L·π·R².

Results
Cylindrical rod mechanical simulation

Volume change dV = (3000+5.1536)·π·(15-0.008589)² - 3000·π·15² = 1210.91 mm³.

Elongation dL, mm Decrease in diameter 2·dr, mm Increase in volume dV, mm³
QuickField 5.1536 0.017178 1210.9
Theory* 5.1557 0.017186 1214.8
Error 0.04% 0.05% 0.3%

* James M. Gere, Stephen P. Timoshenko Mechanics of materials, Third edition (1990), pp.26-27. ISBN:0-534-92174-4.