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Unformatted text preview: Sec_2.8-2.12.qxd 9/25/08 11:44 AM Page 241 SECTION 2.12 Elastoplastic Analysis 241 Solution 2.12-6 Truss consisting of five bars b b b At the plastic load, all five bars
are stressed to the yield stress b F Sum forces in the vertical direction and solve for the load: 2b P 10 mm A pd2
4 Y 1
b + 2F a
(5 12 + 4 15 + 5)
5 2F a PP d 4.2031sYA
2 78.54 mm ; Substitute numerical values:
(4.2031)(250 MPa)(78.54 mm2) PP 250 MPa YA ; 82.5 kN Problem 2.12-7 A circular steel rod AB of diameter d 0.60 in.
is stretched tightly between two supports so that initially the
tensile stress in the rod is 10 ksi (see figure). An axial force P is
then applied to the rod at an intermediate location C. B A
d (a) Determine the plastic load PP if the material is elastoplastic
with yield stress Y 36 ksi.
(b) How is PP changed if the initial tensile stress is doubled
to 20 ksi? A P
C Solution 2.12-7 Bar held between rigid supports
sYA sYA P —C¡ — d 0.6 in.
Y 2sYA p
(2) (36 ksi) a b (0.60 in.)2
4 20.4 k PP ; 36 ksi Initial tensile stress 10 ksi (a) PLASTIC LOAD PP
The presence of the initial tensile stress does not
affect the plastic load. Both parts of the bar must
yield in order to reach the plastic load. (B) INITIAL TENSILE STRESS IS DOUBLED
PP is not changed. ; B ...
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This note was uploaded on 12/22/2011 for the course MEEG 310 taught by Professor Staff during the Fall '11 term at University of Delaware.
- Fall '11