- The yielding stresses for two low-carbon steel tensile specimens with length of 50mm and 100mm are S1 and S 2 ,respectively, elongations are5 and10 respectively，then（ ）
- The cross-sectional area of a piston is A = 2000mm2, when the cylinder is fired, the piston rod issubjected to the maximum axial load of 400kN; When inhaling, the maximum axial pressure is 200kN determine the average stress, stress amplitude and cycle characteristics of the piston rod （ ）
- When the torque T on the cross-section of a round shaft remains unchanged and the diameter is reduced by half, the ratio of the maximum shear stress on the cross-section to the original maximum shear stress is （ ） times.
- The cross-sectional area of a piston is A = 3000mm2, when the cylinder is fired, the piston rod is subjected to the maximum axial load of 600kN; When inhaling, the maximum axial load is 120kN, the average s tress, stress amplitude and cycle characteristics of the piston rod are as follows （ ）
- As shown in the figure, a straight rod AB with a constant cross section, its length is 3a, young’s modulus is E and the cross sectional area is A. Loading condition on rod AB is as shown in the figure, then the vertical displacement of the middle section is: （ ）
- The tensile stress-strain curves of a, b and c are shown in the figure below. Material___with the maximum tensile strength, material ______ with the greatest stiffness, material ________ with the best plasticity. （ ）
- The following figure shows different stress elements(units: MPa), which figure gives 1D stress state （ ）
- Solid circular shaft 1 and hollow circular shaft 2, their cross-sectional area is the same, subject to the same torque, τmax1 and τmax2 are the maximum shear stress of shaft 1and shaft 2 respectively, then （ ）.
答案:(a)>(b)>(c);
答案:S1 S2，5 10.
答案:m=50MPa,a 150MPa,r2;
答案:
答案:
答案:
答案:8
答案:
答案:m=80MPa,a 120MPa,r5
答案:
答案:6Fa/(4EA)
答案:Fa/(EA);
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