# Question 7.6: Fracture in Composites Describe the difference in fracture m......

Fracture in Composites
Describe the difference in fracture mechanism between a boron-reinforced aluminum composite and a glass fiber-reinforced epoxy composite.

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In the boron-aluminum composite, the aluminum matrix is soft and ductile; thus, we expect the matrix to fail in a ductile manner. Boron fibers, in contrast, fail in a brittle manner. Both glass fibers and epoxy are brittle; thus the composite as a whole should display little evidence of ductile fracture.

Question: 7.7

## Strength of Ceramics and Probability of Failure An advanced engineered ceramic has a Weibull modulus m = 9. The flexural strength is 250 MPa at a probability of failure F = 0.4. What is the level of flexural strength if the probability of failure has to be 0.1? ...

We assume all samples tested had the same volume; ...
Question: 7.13

## Design of Links for a Chain Design a ductile cast iron chain (Figure 7-27) to operate in a furnace used to fire ceramic bricks. The chain will be used for five years at 600°C with an applied load of 5000 lbs. ...

From Figure 7-26(b), the Larson-Miller parameter f...
Question: 7.12

## Failure Analysis of a Pipe A titanium pipe used to transport a corrosive material at 400°C is found to fail after several months. How would you determine the cause for the failure? ...

Since a period of time at a high temperature was r...
Question: 7.11

## Design of a Fatigue Resistant Plate A high-strength steel plate (Figure 7-20), which has a plane strain fracture toughness of 80 MPa√m is alternately loaded in tension to 500 MPa and in compression to 60 MPa. The plate is to survive for ten years with the stress being applied at a frequency of once ...

To design our manufacturing and testing capability...
Question: 7.10

## Design of a Rotating Shaft A solid shaft for a cement kiln produced from the tool steel in Figure 7-18 must be 96 in. long and must survive continuous operation for one year with an applied load of 12,500 lb. The shaft makes one revolution per minute during operation. Design a shaft that will ...

The fatigue life required for our design is the to...
Question: 7.9

## Fatigue Failure Analysis of a Crankshaft A crankshaft in a diesel engine fails. Examination of the crankshaft reveals no plastic deformation. The fracture surface is smooth. In addition, several other cracks appear at other locations in the crankshaft. What type of failure mechanism occurred? ...

Since the crankshaft is a rotating part, the surfa...
Question: 7.8

## Weibull Modulus Parameter Determination Seven silicon carbide specimens were tested and the following fracture strengths were obtained: 23, 49, 34, 30, 55, 43, and 40 MPa. Estimate the Weibull modulus for the data by fitting the data to Equation 7-11. Discuss the reliability of the ceramic. ...

First, we point out that for any type of statistic...
Question: 7.5

## Automobile Axle Failure Analysis An engineer investigating the cause of an automobile accident finds that the right rear wheel has broken off at the axle. The axle is bent. The fracture surface reveals a Chevron pattern pointing toward the surface of the axle. Suggest a possible cause for the ...

The evidence suggests that the axle did not break ...
Question: 7.4