Machine Element Design

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امتحان منزلي

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                                                                                                              التوقيع

1- A car has a helical coil spring in its front suspension. The helical spring is made of 17 mm diameter steel wire (d), the main diameter (D) is 136 mm, number of actual coil turns (n) is 10, the free length (L_f) is 400 mm, and the spring has squared ends.

The allowable shear stress for the spring material is 600 MPa. (G = 80 000 MPa). The installed length is 300 mm. The load the spring is supposed to carry (P) is 3000 N.

a) Find the spring index

b) Find the spring rate

c) Find out if the spring is suitable for this car.

    (Check: strength (stress), rigidity (deflection), and buckling)

where: