中国石油大学工程力学考试Exam(11-12-1A)

1、中国石油大学工程力学考试Exam(11-12-1A)中国石油大学（北京）20112012学年第一学期工程力学（双语）期末考试试卷考试方式（闭卷考试）班级：姓名:学号：题号IIIIIIIVVVI总分得分（试卷不得拆开，所有答案均写在题后相应位置）(Total 30 points) Fill up the blanks with correctanswer.Q(4 points) Stress-straincurves for three materials are shown below.Material (1, 2, 3) has the highest ultimatestress. Mat

2、erial (1，2, 3) has the largestelastic modulus.2.(6 points) As shown, a strain gage is pasted on the surface of a circular bar with diameter d to test thetorques acting on two ends. If elastic moduluse and poissionsratio “of the material areknown and thestrainingageis 9thetorquer=(a) t- Es(b) t7idy E

3、g：)T =ndEw(d) 732(1 + “) 764(1 + “)16(1 + “)16%+ “)(4 points) conditions onbeam as shown area.Va)=0,EI V ”)=kv(a)b va)=0,El V (a)=kv(a)c.v”a)=0, ElV ”)= -kv(a)d va)=0,ElV ”)= -kv(a)stress m = , the amplitude of stress a5.(4 points) For two beams made of samematerial, the correct relationship for the

4、ir maximum dynamic stresses is(1) d1Vd2；( 2) d1=d2；( 3)d1 d2;(4) Cannot be judged.节磁节hh6. (4 points) Weight of the body is W, and pushingforce is P W=160N, P=500N. The static and kinetic sliding friction coefficients between the weight and the wall are s=03 and k=025 respectivel y. Then the friction

5、 between the weight and the wall isa. 150N; b. 125N;c. 100N; d. 500N.7.IIDemension in mmand with same diameter.1 NbcJ(,=, =, , =, , =, d2;(4) Cannot be judged.wnT干hhII (13 points) For a beam shown in Fig .11, draw itsbending moment and shear force diagrams. q1 nulI卜C2_m =qaEka aFig. II.P = qaDetnens

6、ion til mtnIll(10 points) Using the method of composite areas, calculate centroidal principal moments of inertia 匚 and for the shaded region as shown in Fig .III.Fig. III.IV (15 points) For the static indeterminate beam, find the reaction at B with energy method. ei is known。彳PBi b ta,V. (20 points)

7、 A horizontal bracket ABC is fixed atsupport A and free at C. The bracket is constructedfrom a circular cross-sectionabar with constant diameter d. A vertical load P acts at the free end C. Determine the places of the critical points. (2) Draw stress elements to show the stressstate of the critical

8、points. (3) If d = 30mm, a = 1m, P = 180N and the allowable stress is = 80MPa, exam the strength of the bracket according to the 3 strength conditio n.VI.(12 points) For the prismatic bar, taking its weight in consideration, find the displacementof section B. Loading F, l, cross section areaA,elasti

9、c modulus E and mass density p areknown.中国石油大学（北京） 2011 2012学年第一学期工程力学（双语）期末考试试卷考试方式（闭卷考试）班级：姓名：学号：题号IIIIIIIVV总分得分（试卷不得拆开，所有答案均写在题后相应位置）I (Total 40 points) Fill up the blanks with correct answer.1. (5 Points)Fig.1.1 is a typicallow-carbon steel - diagram in tensio n. Such a diagram conveys important

10、 information about the mechanical behavior for the material. Point a represents _, point b represents _,point c represents, point d represents一 point e represents _.(1) yield stress (2) ultimate stress (3) elastic limit(4) percent elongation (5) proportional limitFig .1.12. (5 points) A piece of cha

11、lk shown in Fig .1.2 is subjected to a combination of twisting andtension, fails on the a-degree plane with the longitudinal axis. The senses of the torques andaxial forces must beindicated as shown inFig. 1.23. (5 Points) For a real member undergoing repeated stress, its character of cycle r=.When

12、r =,its endurance limitis thesmallest.a.二b%axc. +1d.-e.amax%in0f.g. 0.54. (5 points)The boundary Lconditions on left end for a。beam as shown ar.a. Va)=0,EI V ”)=kv(a)b.va)=0, EIV (a)=kv(a)c.v”a)=0, ElV ”)= -kv(a) d. va)=0,Elv ”)= -kv(a)Ayx5. (5 points) When a train pass through a steel bridge, the s

13、trains tested by instrument are x = 0.0004, y = -0.00012 at point A. The normal stresses in directions x andy at point A are x = , y=. (E=200GPa, =0.3, z=0)6. (5 points) For two beams made of same material,the correct relationship for their maximumdynamic stresses js(3)(1) d1Vd2；(2) d1=d2；d1 d2;(4)

14、Cannot be judged.thwaT7. (5 points) Weight of the body is W, and pushingforce is P. W=160N, P=500N. The static and kinetic sliding frictioncoefficients between the weight andthe wall are s=0.3 and k=0.25 respectively. Thenthe friction between the weight and the wall isa. 150N;b. 125N;c. 100N;d. 500N

15、.8. (5 points) The bars in Jthe structures as following are made L (i)卩of same materialand with same diameter. 1 Nbc1 1(,=,II (15 points) For a beam shown in Fig .11, draw its bending moment and shear force diagrams.ig-2m B fa q-paIll(15 points) In figure there is a manual winch. Thediameter of thst

16、eel .袖 allowable stress imaximum Iowinchft is d=30mm and the180囱a Find therding to the 4strength conditio n.EJIV (15 points) A rigid bar AB of length L is hinged to a wall at A and supported by two vertical bars labeled 1 and 2 attached at points C and D. The bars 1 and 2 have the same cross-section

17、al area A and are made of the samematerial (modulus E), but the bar 2 is twice as long as the bar 1. (a) Find the tensile forces N 1 and N2 in the bars due to the vertical load P acting at end B of the bar. (b) Find the downward displacement b at end B of the bar.pr21n4T-DD-B4+11L1PL V. (15 points) Find the reaction at the support B for the beam with loads as following. (