Question

The shaft shown in Figure is supported by bearings cach end, which have bores of 20.0 mm. Design the shaft to carry the given load if it is steady and the shaft is stationary. Make the dimension a as large as possible while keeping the stress safe. Determine the required diameter in the middle portion. The maximum fillet permissible is 2.0 mm. Use SAE 1137 cold-drawn steel. Use a design factor of 3 The material properties are as follows:- Q-1 at S'n 188 Sy 565 MPa Su 676 MPa MPa K, 1.8 Is48 4 D -1- Q-2 Figure shown below shows a hydraulic cylinder that pushes a heavy tool during the outward stroke, placing a compressive load of 400 N in the piston rod. During the return stroke, the rod pulls on the tool with a force of 1500 N. Compute the resulting design factor for the 15- mm-diameter rod when subjected to this pattern of forces for many cycles. The material is SAE 4130 WQT 1300 steel. If the resulting design factor is much different from 4.0, determine the size of rod that would produce N 4.0 Ahemating Pion rod fonce 15 mm Q-3 A leaf spring in an automobile is subjected to cyclic stresses. The average stress 150 MPa; variable stress 500 MPa; ultimate stress 630 MPa; yield point stress 350 MPa and endurance limit 150 MPa. Determine the factor of safety (design factor) of the spring by Goodman

Answer 1

Q-1 the shaft is given Desigm stess Sy as N design factos - 3 Nニ - 188 33 N/mm2 565 MPa 188.33 MPa is as fo Qloss boddiaqom of the shaft Fee 5.4 KM A 25 mmM Rc RA RA+ Rc 5A KN uayt 7 RA 2.7 kN abovt Take moment 54メ125 RA メ 250= Rc = 2.7 KN is Fe= -2-7KN Point Sheat is FA2.7 KN A poini Shea foxce at Also, a point uawiowl \S Bending Now 5.4 X 125 2.子×25o MA = IS momeni as point B bending A9so 337.5 N- mm 2.子 ×125 Me point C is at uawiowl bending Simi ax 5-4X 125 EPW 2-7メ 25O

Shear e and Berding foMows wasbop of mom end the beam IS as 27 KN Sheax fosre - 27 KN X 337-5 KN-mm Bending Momen M 2.7x Secton mouus of he shaft is as folows 339.5 x13 N-mm 792. 07 mm S= 18.33 mm 2 Now know hot S= £OCEEI tE 26 33 m 32 diametes of the middle pokon of the that So Shaft BRanding) is D= 30 mm moduus f is 6Joys the stepped prton Nowthe section 3 T (20. 785.4 mm 32 32 that fuS uiOUl M= aS= 18833 メ 85.4 So M EN-mm that value of the dimension o.f the shaft is So 'a 147. 914 KN-mm = U 2:7 KM 55mm 9ニ54-7g mm 2.7 KN