Question

Question 6 A composite spning has two close-coiled helical springs in series One spring is made of steel with a mean coil diameter of 15 mm, wire diameter 15 mm and has 10 coils The other spring is made from bronze with a mean coil diameter of 20 mm and wire diameter of 2 mm and B coils Calculate 61 The stiffness of the composite spring, 62 The greatest load that can be camned by the composite spring of the maximum allowable stresses are 150 MPa and 80 MPa in the steel and bronze respectively 63 The corresponding extension, 64 The strain energy in the composite spring [G = 80GPa; Gb = 40GPa)

Answer 1

The greatest load the spring can carry based on the maximum shear stress criteria is lesser of these two W values, i.e. 12.56 N.

sludion Di-15m R, 7.5m di Smm Spung 1 10 poD Nory 1ING29 1 Spig2 10 o ud D2 20m R210mn d2 2m :en Abo G 80GPA (a)8o N fn1SoMa १ - i) S cempeaie apng tsma oMa Asthe opugs au cenmeckd in eruo 2mey S L osS W 2! Coruep 22 ennou W WW (e St Sp S drgun broonc 1 3 64 R, ni + St Gd L 64 x 10 (o)x 8 (1-5) 833.33+ So0) 8ox0 64 त पता्कि o N/ St 9 99F (2)t 937N St 0.331 N ) Gaalest Read W2 Fer opig 1, W1Sox Tx(s 8 x IS s 13.246 N boot:9 bro पत o how -12 56 N 8x 20 KAD(5910 Thus gualst lood, that the oping con caouy bard en mox ohen tao o 12.56N 80 x72 Fet opns 2, W ane lhisMobes ww.

Extension is also called deflection. When springs are connected in series, total extension is the sum of individual extensions.

0) Ceneo padig ecli on Tn oio, SS+ s Gd 64 RS m W. 12 56 8.373 15 Smlardy 5.0 24 theror 8 373 5024 13. 397 Staeengy E N8 L (256)(3-397x0 2 -168) 2 = 0.084 o Nm ) 84 Nmm