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Mechanics of Solids 2011 Part 2

Tham khảo tài liệu 'mechanics of solids 2011 part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 1-14 Section 1 Fo 100 N j E Mo 0 Mo Mc roX X Wx roB X W 0 Mo 100i - 20 j 50k N m 0.6i - 0.3 j 0.4k m X -60 N j i - 0.2 j m X -40 N j 0 M 100 N m i - 20 N m j 50 N m k- 36 N m k 24 N m i - 40 N m k 0 O MO -124i 20 j 26k N m Example 4 A load of 7 kN may be placed anywhere within A and B in the trailer of negligible weight. Determine the reactions at the wheels at D E and F and the force on the hitch H that is mounted on the car for the extreme positions A and B of the load. The mass of the car is 1500 kg and its weight is acting at C see Figure 1.2.16 . FIGURE 1.2.16 Analysis of a car with trailer. Solution. The scalar method is best here. Put the load at position A first For the trailer alone with y as the vertical axis IMf 7 1 - Hy 3 0 Hy 2.33 kN On the car Hy 2.33 kN ị Ans. ỶFy 2.33 - 7 Fy 0 Fy 4.67 kN T Ans. For the car alone TMe -2.33 1.2 - Dy 4 14.72 1.8 0 Dy 5.93 kN ĨAns. ỶFy 5.93 Ey - 14.72 - 2.33 0 Ey 11.12 kN T Ans. Put the load at position B next For the trailer alone IMf 0.8 7 - Hy 3 0 Hy -1.87 kN On the car Hy 1.87 kN ị Ans. ỵFy -1.87 - 7 Ey 0 Ey 8.87 kN T Ans. For the car alone IMe - 1.87 1.2 - Dy 4 14.72 1.8 0 Dy 7.19 kN T Ans. ỵFy 7.19 Ey - 14.72 - -1.87 0 Ey 5.66 kN T Ans. Forces and Moments in Beams Beams are common structural members whose main function is to resist bending. The geometric changes and safety aspects of beams are analyzed by first assuming that they are rigid. The preceding sections enable one to determine 1 the external supporting reactions acting on a statically determinate beam and 2 the internal forces and moments at any cross section in a .