课程名称︰材料力学 课程性质︰必带 课程教师︰朱锦洲 开课学院：工学院 开课系所︰化工系 考试日期（年月日）︰2011/11/01 考试时限（分钟）：110 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : 1.explanation (a)Mechanics of materials (b)Free-body diagram (c)Plane stress and plane strain (d)Shear stress and shearing strain (e)Statically determinate and statically indeterminate (f)Strain rosettes 2.A bar rack is sketched as shown in Fig.2. If each bar has a mass 10Kg. Determine (a)the reaction at the supports A and B, (b)the internal force at section a-a 3.At a point in a structural member subjected to normal and shear stresses on horizontal and vertical planes as shown in Fig.3. (a)Determine and show on a sketch,(i) the principal stresses,(ii) the maximum shearing stress and (iii) the maximum in-plane shearing stress at the point. (b)Determine and show on a sketch, the normal and shear stresses at the point on the inclined plane a-b at the point. (c)Use Mohr's circle to verify your answers in (a) and (b). 4.A point in a body subjected to plane strain, if εx=+500μ, εy=-300μ and εp1=+1000μ(one principal strain) are given, please determine (a)the shearing strain γxy (b)the other two principal strains, εp2 and εp3 (c)γmax (max. shearing strain) (d)the in-plane principal directions, θp (e)Prepare a sketch showing the principal strain deformations and the maximum shearing strain distortions. (f)Use Mohr's circle to verify your answers. 5.Member AD of the timber truss shown in Fig.5 is framed into the 100x150-mm bottom chord ABC as shown in the insert. Determine the dimension a that must be used if the average shearing stress parallel to the grain at the ends of chord ABC is not to exceed 3.0 MPa. Figure: http://ppt.cc/YfRY --

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