The expectation would likely be hot-rolled steel. If it is desired to confirm this, either a weight or bending test could be done to check density or modulus of elasticity. The weight test is faster. From the measured weight of 7. Nickel steel and stainless steel have similar unit weights, but surface finish and darker coloring do not favor their selection.
To select a likely specification from Table A, perform a Brinell hardness test, then use Eq. Assuming the material is hot-rolled due to the rough surface finish, appropriate choices from Table A would be one of the higher carbon steels, such as hot-rolled AISI , , or Results from these three favor a softer, non-ferrous material like aluminum. From the measured weight of 2. No other materials come close to this unit weight, so the material is likely aluminum.
Results from these three favor a softer, non-ferrous copper-based material such as copper, brass, or bronze. To further distinguish the material, either a weight or bending test could be done to check density or modulus of elasticity. From the measured weight of 9 lbf, the unit weight is determined to be W 9. Brass is not far off 0.
The conclusion is that the material is likely copper. They are close enough that other factors, like cost or availability, would likely dictate the best choice.
Polycarbonate polymer is clearly not a good choice compared to the other candidate materials. The section modulus is strictly a function of the dimensions of the cross section and has the units in3 ips or m3 SI. Then, for strength, Eq. Students of this text should find that it inherently directs them into familiarity with both the basis for decisions and the standards of industrial components.
For this reason, as students transition to practicing engineers, they will find that this text is indispensable as a reference text. The objectives of the text are to:. This was followed by another transition to 3D solid modeling, where the part was drawn with ideal dimensions. Unfortunately, this ability to draw a perfect part in three dimensions is all too often accompanied by a neglect of focus on how to accurately and uniquely represent the part for. Some mechanical engineers will benefit from such a rigorous training.
It is always a challenge to find time to include additional material in a course. To facilitate this, the chapter is arranged and presented at a level appropriate for students to learn in an independent study format. The problems at the end of the chapter are more like quiz questions, and are focused on checking comprehension of the most fundamental concepts.
Instructors are encouraged to consider using this chapter as a reading assignment, coupled with even a minimal lecture or online discussion. Further discussion of the development of the design factor is presented, as well as the statistical relationships between reliability and the probability of failure, and reliability and the design factor.
Statistical considerations are provided here rather than in a chapter at the end of the text as in past editions.
Students of this text should find that it inherently directs them into familiarity with both the basis for decisions and the standards of industrial components. For this reason, as students transition to practicing engineers, they will find that this text is indispensable as a reference text. This was followed by another transition to 3D solid modeling, where the part was drawn with ideal dimensions. Unfortunately, this ability to draw a perfect part in three dimensions is all too often accompanied by a neglect of focus on how to accurately and uniquely represent the part for manufacture and inspection.
Some mechanical engineers will benefit from such a rigorous training. All mechanical engineers, however, should be familiar with the basic concepts and notation. It is always a challenge to find time to include additional material in a course. To facilitate this, the chapter is arranged and presented at a level appropriate for students to learn in an independent study format.
The problems at the end of the chapter are more like quiz questions, and are focused on checking comprehension of the most fundamental concepts.
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