## TECH 3513 Material Tests and Analysis

#### CHAPTER 7 HOMEWORK

7.49 The area under each curve in Figure 7.11 on page 179 is estimated by adding the areas under the initial elastic region and the flat regions under the curve. This area under the curve is toughness. The data is given in the table below. Plot the graph of the Toughness (y axis) versus Temperature (x axis) (plot the points and then draw a curve through the points). Use the scale from -40 to 100 by 20 on the x-axis and use the scale 100 to 800 by 100 on the y-axis.

__Temperature (oC) Toughness (Mj/m3)__

-25 140

0 635

25 760

50 730

65 520

80 270

7.51 Use the materials shown in the table below. The formula for maximum deflection (d) of a cantilevered beam is d = P * L3 / (3 * E * I), where P is the load (50 kg = 490 N, use P = 490 N), L is the beam length (L = 1 m), E is the elastic modulus, and I is the moment of inertia (I = b*h3/12, where b = 0.02 m and h = 0.075 m, so I = 7.03 x 10-7). Calculate the maximum deflection. ANSWER IN METERS.

__Material Elastic Modulus (E) (Pa)__

ABS 2.1 x 109

Acetal 2.45 x 109

Epoxy 10.25 x 109

ABS, reinforced 7.5 x 109

Acetal, reinforced 10 x 109

Epoxy, reinforced 36.5 x 109

Aluminum 70 x 109

Steel 195 x 109

Note: The results show that ABS has the most deflection and steel the least.

7.53 Use the table of values below. The formula for required weight (N) is W = *p ** g * F * L / σy where *p* is the density, g is the gravitational constant (9.81 m/s2), F = 5000 N, L = 1 m, and σy is the UTS. Calculate the required weight. ANSWER IN KILOGRAMS.

__Material Density ( p) (kg/m3) UTS (σy) (N/m2)__

HMW polyethylene 950 2.4 x 107

Polyester 1270 5 x 107

Rigid PVC 1400 4.1 x 107

ABS 1030 3 x 107

Polystyrene 1000 3.2 x 107

Reinforced nylon 1130 9 x 107

Click here to download the answer sheet for Chapter 7 Homework

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Required Textbook

- Kalpakjian & Schmid (2014), Manufacturing Engineering and Technology, 7th Edition, Pearson Education, Inc.
- ISBN-13: 978-0-13-312874-1