The average stress σm and stress amplitude σa of the alternating stress in the figure are respectively ( ).[img=239x154]17de8405f43ce66.jpg[/img]
A: σm = 40MPa，σa = -120 MPa
B: σm = -40MPa，σa = -40 MPa
C: σm = 0MPa，σa = 120 MPa
D: σm = -40MPa，σa = 80 MPa
A: σm = 40MPa，σa = -120 MPa
B: σm = -40MPa，σa = -40 MPa
C: σm = 0MPa，σa = 120 MPa
D: σm = -40MPa，σa = 80 MPa
举一反三
- If the beam is subjected to a bending moment of M = 16 kN.m, the maximum bending stress inthe beam is ( ). [img=758x530]17de83378488e00.jpg[/img] A: 48.6 MPa B: 74.5 MPa C: 59.6 MPa D: 85.4 MPa
- If the beam is subjected to a bending moment of M = 15 kN.m, the maximum bending stress inthe beam is ( ). [img=443x401]1803275dfac22cc.jpg[/img] A: 5.88 MPa B: 3.92 MPa C: 1.96 MPa D: 7.84
- The bending stress developed at corners A is ( ). [img=480x470]1803275e1832bda.jpg[/img] A: 30 MPa (Tension) B: 30 MPa (Compression) C: 42 MPa (Tension) D: 42 MPa (Compression)
- 原油压缩系数单位是（）。 A: kg/m B: MPa C: MPa～1 D: MPa•s
- 井筒储集常数的单位是（）。 A: m/Pa B: m/MPa C: MPa/m D: m.Pa