Note: Time: 8:00am-9:55am. You can only use the formula provided by instructor a

Question

Note: Time: 8:00am-9:55am. You can only use the formula provided by instructor and calculator during the exam. Using any other devices (including phone) or materials is prohibited. Write your answers on blank papers. Do not write on this exam sheets. Return both the exam sheets and solution sheets separately 1. (12 pts) Provide the answers of the following questions. You will not receive any partial credits by showing your work. (1.1) What is the approximate percentage of carbon content in G (a) 0.4096; (b) 1096; (c) 9096; (d) 20%; (1.2) The ultimate strength of t he steel is 1020MPa. What is the Brinell Hardness Hs of the steel? (a) 3468; (b) 2040; (c) 300; (d) 510 (1.3) Which one of the following operations is false when determining the forces and moments using a free-body diagram of a beam or beam section? (a) Sum moments equal zero; (b) Moments are determined independent of shear forces; (c) Sum forces equal zero; d) Sum reaction forces equal sum of the imposed forces. (1.4). A beam is subjected to two bending moments M, and M, as shown below. On the cross section of the beam, where does the maximum tension stress occur? (a) A; (b) B; (c) C (d) D. (1.5) Name the four different types of loads.

Explanation / Answer

1.1) The % of carbon in G1040 steel is 0.37-0.44.

So the correct answer for this question is Option "a" ie, 0.40%

1.2)The relation ship between ultimate tensile strength(UTS) and Brinell hardness(BHN) number is

BHN=3.4*UTS

BHN=3.4*1020

BHN=3468

So the correct answer is Option "a"

1.3) For a body to be in equilibrium the algebric sum of forces acting on a body is equal to zero.

To satisfy this condition the algebric sum of reation forces should be equal to algebric sum of imposed forces.

The algebric sum of moments about any point, by all the shear forces and moments should be equal to zero.

Based on the above statements we can say that option "b" is false.

1.4) When the moment Mz is applied along the Z -axis the top most fiber(AB) will be in tension and bottom most fiber(CD) in compression.

When the moment My is applied along the Y-axis then the top most fiber (BD) will be in tension and the bottom most fiber (AC) in compression.

From the above statements we can say that The point B will have more tensile stress.

So Option "b" is correct.

1.5) The four types of loads are

a) Tensile load

b) Compression Load

c) Bending Load

d) Tortional load

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