재료역학 연습문제 1.2 부분에 관한 문제풀이 입니다
1.2-1) A solid circular post ABC(see figure) supports a load =2500lb acting at the top. A second load is uniformly distributed around the shelf at B. the diameters of the upper and lower parts of the post are =1.25in. and =2.25in. respectively
(a) Calculate the normal stress in the upper part of the post
(b) If it is desired that the lower part of the post have the same compressive stress as the upper part, what should be the magnitude of
the load ?
1.2-3) A steel rod 110 ft long hangs inside a tall tower and holds a 200-pound weight at its lower and (see figure)
If the diameter of the circular rod is 1/4 inch, calculate the maximum normal
stress in the rod, taking into account the weight of the rod itself.
(Obtain the weight density of steel from Table H-1,appendix H)
1.2-4) A Circular aluminum tube of length L=40 mm is loaded in compression by forces P(see figure). the outside and inside diameters are 60 mm and 50 mm,respectively. A strain gage is placed on the outside of the bar to measure normail strains in the longitudinal direction
(a) If the measured strain is , What is the shortening of the bar?
(b) If the compressive stress in the bar is intended to be 40MPa, what should be the load P?
1.2-5)the cross section of a concrete pier that is loaded uniformly in compression is shown in the figure
(a) Determine the average compressive stress in the concrete if the load is equalto 2500 k
(b) Determine the coordinates X and Y of the point where the resultant load must act in order to produce uniform normal stress
1.2-9) A loading crane consisting of a steel girder ABC supported by a cable BD is subjected to a load P (see the figure on the next page). The cable has an effective cross-sectional area A=0.471 . the cimensions of the crane are H=9ft, =12ft and =4ft
(a) If the load P=9000lb, what is the average tensile stress in the cable?
(b) If the cable stretches by 0.382in, what is the average strain?