Question

13.1

Brass R Aluminum The composite beam shown is formed by bonding together a brass rod and an aluminum rod of semicircular cross sections. The radius of the beam is 0.94 in. The modulus of elasticity is 12.9 x 106 psi for the brass and 8.6 x 100 psi for the aluminum. Knowing that the composite beam is bent about a horizontal axis by couples of moment 7.7 kip.in, determine the maximum stress in the brass. Assumethe moment is applied to put the brass in compression and the answer should be in ksi with 1 digit of accuracy.

Answer 1

Brals. N A Aluminicem Bending Radius: 0.94 inch. Eb = 12.9 x 66 psi tal = 8.6% os Psi moment:_7.7_Hip-incha strein Know that strets en Aleminicem - Brass, бе. Obrass EP.1 Ebrocess we Tal= bal xoh. 8. 6x06 x6b Eb 12-9x600 Che.= 0.667 66. Both bosals f Aleminicum has some are so n.2 axis. Posses through Center of both I brouss - I Aluminium & π xd4 - " x 1188" 728 128 CS Scanned with -Caricarmer = 0.3065 inchu

form: Beading epeation M: JI Total moment. M = Mb + MAL. YAL 7.7=CAl tips to booss x I boas Јbrow y distance of top fiber foo NA. Y=0.94inch. 'forb brookef Aluminiu.co) 77-0.66768x0.3065 +66 40.3065 0.94 7.7 0.543.566.. 66 - 14.166 R6i. . 0.94 maximere allowble stoegs in baseks - 14.166 vsi CS Scanned with CamScanner

Brass subjected to compressive stress.

therefore maximum allowable compressive stress in brass = 14.166 ksi.