材料力学课堂教学软件（英文版）-范钦珊-chap.1 Fundamental Conception.pptVIP

* * * TSINGHUA UNIVERSITY * TSINGHUA UNIVERSITY HIGHER EDUCATION PRESS BEIJING CHINA Fan’s Studio for Education and Teaching Prof.Fan’s Studio for Education and Teaching Back to main Menu (1) Guide to Solve Problems of Mechanics of Materials April 14, 2003 Q.S.Fan Tsinghua University P.R.CHINA Chapter.1 Mechanics of Materials Fundamental Conceptions of Mechanics of Materials Back to the first page Back to main Menu Problem : A rectangle-section pole with right end fixed is shown in the first figure. A force couple M is applied to the symmetric section of the left end of the pole. Among the four answers below about the distribution of the internal force in the A-A section at the fixed end, which is the reasonable answer, according to the characteristics of elastic bodies? Problem 1 Back to the first page The First Kind of Exercise: The Relation between Stress , Internal Force and Load Solution: Cutting through A-A section, for equilibrium conditions, the distributed internal force in this section should form a force couple in order to balance the force couple M applied to the left end. But in answers (A) and (B), the internal force forms either a force or a combination of force and force couple. So (A) and (B) are incorrect. Problem 1 Back to the first page The First Kind of Exercise: The Relation between Stress , Internal Force and Load When a pole is subjected to a pair of force couples, bending deformation occurs. In this case, the upper part of the pole is under compression and the nether part is under tension, and the tension and compressive forces do not uniformly distribute in the section. So the answer (D) is incorrect. The right answer is C Problem 1 Back to the first page The First Kind of Exercise: The Relation between Stress , Internal Force and Load Problem : The bar ACB is fixed at end A and end B, as shown in the first figure. Analyze which answer about the constraint force at end A and end B is reasonable.