Chapter 6, Problem 6.26P

5. (计算题) Calculate the DOF of the following mechanism D A B E

4.(计算题) Calculate the DOF of the following mechanism wwwww التحفة www

VIMA

1. Calculation Calculate the DOF of the following mechanis m 2 3 1 Please enter the answer

a) Determine state of stress at all points (a, b and c). These points are located on the exteriorsurface of the beam. Point a is located along the centreline of the beam, point b is 15mmfrom the centreline and point c is located on the edge of the beam. Present yourresults in a table and ensure that your sign convention is clearly shownb) Construct Mohrs circle at this point andcalculate the principal stresses and maximum in‐plane shear stress (τmax) at pointc. sketch the resulting state of stress at this point clearly indicating themagnitude of the stresses and any angles associated with the state of stress (principal ormaximum in‐plane shear).

parts e,f,g

Figure 9-6 9-49 An aluminum alloy plate with dimensions 20 cm x 10 cm × 2 cm needs to be cast with a secondary dendrite arm spacing of 10-2 cm (refer to Figure 9-6). What mold constant B is required (assume n = 2 )? Secondary dendrite arm spacing (cm) - 10-1 10-2 10-3 10 41 0.1 1 Copper Zinc alloys Aluminum alloys 10 100 1,000 10,000 100,000 Solidification time (s)

9-72 Figure 9-29 shows a cylindrical riser attached to a casting. Compare the solidification times for each casting section and the riser and determine whether the riser will be effective. Figure 9-29 Т 3 6 3 8 3 6 Details A diagram shows the step-block casting. A cylinder of height "7" and diameter "3" is kept on a platform consisting of 2 steps. The width of the second step of the platform is labeled as "3". The horizontal length of the first step is labeled as "6." The horizontal length, width and height of the first step are labeled "6", "8" and "3".

6/94 Determine the minimum coefficient of static friction for which the bar can be in static equilibrium in the config- uration shown. The bar is uniform and the fixed peg at C is small. Neglect friction at B. A L PROBLEM 6/94 B L 22