工程力学习题答案第6章 弯曲.docx

第6章弯曲 习题答案6-11F213F 9F 336-12 qA =必二,Fsmax= F,MA 4。 B 4。 5mdX 323F 9F 336-12 qA =必二,Fsmax= F,MA 4。 B 4。 5mdX 32max646-14实心轴oax = 159MPa ,空心轴bmax =93.6MPa ,空心截面比实心截面的最大正应力减少了 41%615 bx > 41.7/72/72, h = 125.rrvn , b2 > 40iTun,h2 = 120mm616 b > Til mm. /z > 416mm6 17 /?= 102mm, /?=153mm6-18 d=278mm h rr6-19 = J26-20 %=237cm3,1206/6-216-21b% maxr ib 2 =22.5MPa<af , jjl “ ， Cmaxz2Mcyl= 33.9MPa<ac6-22=15.68 kN/m6-236-24/截面 b/max=88.2Ma,max = 147.lMP。夕截面 b/max = 115.lMPa,b(n1ix = 69 A MPa bmax = 705MRz，=x0.478M7% 6-25 bxh = 140x210mm26-26 F = 3.75kN6-27 边界条件：玉=0, j = 0; xx - Z, w = 0连续条件：玉=x2 = I, Wj = w2,0 = 02应分三段，边界条件为：x = 0,wA =0, x = a,0 =0B2 ；, x = 2q, Wg = wc,x = 3a, 6D = 0, wD = 05q6-29(1)= 一0 768 EI力=生，小也6EI b SEI*=-金Fa(24/+16。/ 3/2)(4)48。(3/2-16al-16a2)ec =-(5l + 12awc =-(51 +6a) c 24 EIc24 EI"鲁w仔(6)八qa3qa2lql3 qaqa3lu -1, w -1c6EI6EI24 EIc SEI6EIql3 a24 EI6-30 0c5Fa24 EI_ 3Fq3 2EI6-31 d=112mm