EBK MANUFACTURING ENGINEERING & TECHNOL
7th Edition
ISBN: 8220100793431
Author: KALPAKJIAN
Publisher: PEARSON
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Textbook Question
Chapter 2, Problem 21RQ
Why does the fatigue strength of a specimen or part depend on its surface finish?
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A specimen of a ceramic material having an elastic modulus of 250 GPa (36.3 x 106 psi) is pulled in tension with a stress of 750 MPa (109,000 psi). Will the specimen fail if its “most severe flaw” is an internal crack that has a length of 0.20 mm (7.87 x 10-3 in.) and a tip radius of curvature of 0.001 mm (3.94 x 10-5 in.)? Why or why not?
Given your understanding of what initiates and controls failure in materials, which of the following will increase the failure strength or lifetime
of a test piece or component and why?
a. Polishing to reduce surface defects
b. Decreasing the temperature below the brittle-ductile transition temperature, to make it harder
C. Increasing its volume, to give a larger cross sectional area
d. Increasing the grain size so there are less grain boundaries to initiate failure
e. Decreasing the difference between the maximum and minimum stress values, as this effects the stress concentration factor
What is the small strain analysis in the engineering design?
Chapter 2 Solutions
EBK MANUFACTURING ENGINEERING & TECHNOL
Ch. 2 - Distinguish between engineering stress and true...Ch. 2 - In a stress-strain curve, what is the proportional...Ch. 2 - Describe the events that take place when a...Ch. 2 - What is ductility, and how is it measured?Ch. 2 - In the equation =Kn, which represents the true...Ch. 2 - What is strain-rate sensitivity, and how is it...Ch. 2 - What test can measure the properties of a material...Ch. 2 - What testing procedures can be used to measure the...Ch. 2 - Describe the differences between brittle and...Ch. 2 - What is hardness? Explain.
Ch. 2 - Describe the features of a Rockwell hardness test.Ch. 2 - What is a Leeb test? How is it different from a...Ch. 2 - Differentiate between stress relaxation and creep.Ch. 2 - Describe the difference between elastic and...Ch. 2 - Explain what uniform elongation means in tension...Ch. 2 - Describe the difference between deformation rate...Ch. 2 - Describe the difficulties involved in conducting a...Ch. 2 - What is Hookes law? Youngs modulus? Poissons...Ch. 2 - Describe the difference between transgranular and...Ch. 2 - What is the reason that yield strength is...Ch. 2 - Why does the fatigue strength of a specimen or...Ch. 2 - If striations are observed under microscopic...Ch. 2 - What is an Izod test? Why are Izod tests useful?Ch. 2 - Why does temperature increase during plastic...Ch. 2 - What is residual stress? How can residual stresses...Ch. 2 - On the same scale for stress, the tensile true...Ch. 2 - What are the similarities and differences between...Ch. 2 - Can a material have a negative Poissons ratio?...Ch. 2 - It has been stated that the higher the value of m,...Ch. 2 - Explain why materials with high m values, such as...Ch. 2 - With a simple sketch, explain whether it is...Ch. 2 - Explain why the difference between engineering...Ch. 2 - Consider an elastomer, such as a rubber band. This...Ch. 2 - If a material (such as aluminum) does not have an...Ch. 2 - What role, if any, does friction play in a...Ch. 2 - Which hardness tests and scales would you use for...Ch. 2 - Consider the circumstance where a Vickers hardness...Ch. 2 - Which of the two tests, tension or compression,...Ch. 2 - List and explain briefly the conditions that...Ch. 2 - List the factors that you would consider in...Ch. 2 - On the basis of Fig. 2.5, can you calculate the...Ch. 2 - If a metal tension-test specimen is rapidly pulled...Ch. 2 - Comment on your observations regarding the...Ch. 2 - Will the disk test be applicable to a ductile...Ch. 2 - What hardness test is suitable for determining the...Ch. 2 - Wire rope consists of many wires that bend and...Ch. 2 - A statistical sampling of Rockwell C hardness...Ch. 2 - In a Brinell hardness test, the resulting...Ch. 2 - Some coatings are extremely thinsome as thin as a...Ch. 2 - Select an appropriate hardness test for each of...Ch. 2 - A paper clip is made of wire 0.5 mm in diameter....Ch. 2 - A 250-mm-long strip of metal is stretched in two...Ch. 2 - Identify the two materials in Fig. 2.5 that have...Ch. 2 - Plot the ultimate strength vs. stiffness for the...Ch. 2 - If you remove the layer of material ad from the...Ch. 2 - Prove that the true strain at necking equals the...Ch. 2 - Percent elongation is always defined in terms of...Ch. 2 - You are given the K and n values of two different...Ch. 2 - A cable is made of two strands of different...Ch. 2 - On the basis of the information given in Fig. 2.5,...Ch. 2 - In a disk test performed on a specimen 1.00 in. in...Ch. 2 - A piece of steel has a hardness of 300 HB....Ch. 2 - A metal has the following properties: UTS = 70,000...Ch. 2 - Using only Fig. 2.5, calculate the maximum load in...Ch. 2 - Estimate the modulus of resilience for a highly...Ch. 2 - A metal has a strength coefficient K = 100,000 psi...Ch. 2 - Plot the true stresstrue strain curves for the...Ch. 2 - The design specification for a metal requires a...Ch. 2 - Calculate the major and minor pyramid angles for a...Ch. 2 - If a material has a target hardness of 300 HB,...Ch. 2 - A Rockwell A test was conducted on a material and...Ch. 2 - For a cold-drawn 0.5% carbon steel, will a...Ch. 2 - A material is tested in tension. Over a 1-in. gage...Ch. 2 - A horizontal rigid bar cc is subjecting specimen a...Ch. 2 - List and explain the desirable mechanical...Ch. 2 - When making a hamburger, you may have observed the...Ch. 2 - An inexpensive claylike material called Silly...Ch. 2 - In tension testing of specimens, mechanical and...Ch. 2 - Demonstrate the impact toughness of a piece of...Ch. 2 - Using a large rubber band and a set of weights,...Ch. 2 - Find or prepare some solid circular pieces of...Ch. 2 - Take several rubber bands and pull them at...Ch. 2 - Devise a simple fixture for conducting the bend...Ch. 2 - By pressing a small ball bearing against the top...Ch. 2 - Describe your observations regarding Fig. 2.14c.Ch. 2 - Embed a small steel ball in a soft block of...Ch. 2 - Devise a simple experiment, and perform tests on...Ch. 2 - Obtain some solid and some tubular metal pieces,...Ch. 2 - Explain how you would obtain an estimate of the...Ch. 2 - Without using the words stress or strain, define...Ch. 2 - We know that it is relatively easy to subject a...
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.Similar questions
- What are the experimental techniques used to measure the strain?arrow_forwardWhat must be true about the dimensions of a plate in order for plane-strain conditions to apply?arrow_forwardAs Fast As you can Please mak sure the answer is correct 100% Please match the following to the appropriate areas or sublocations illustrated on the steel stress-strain curve shown below: (ultimate tensile stress- yield stress - repture stress) (4) The maximum stress point on the stress strain curve. (2) The point where the proportional limit ends and the moment the elastic limit of the specimen is reached, the specimen will return to its original state after the loading is removed. Typically occurs before the steel specimen starts to plastically yield. (5) The point at which the steel specimens has underwent necking and breaks. This typically occurs after the maximum stress is reached during the experiment.arrow_forward
- (one or more option can be true please select from below) which of the following will reduce the failure strength or lifetime of a test piece and why? Decreasing the grain size, more grain boundaries to initiate failure Raising the temperature above the BDTT, more plastic deformation in the lattice will cause it to fail faster Increasing its volume, greater likelihood of critical defects Decreasing the loading frequency, the material will be at peak stress values for longer Increasing the difference between the maximum and minimum stress values, as this affects the stress concentration factorarrow_forwardWhat are the main features of the Rockwell Hardness Test?arrow_forwardplease just a three questions left I need answers for them .arrow_forward
- I need all answerarrow_forwardanswer quicklyarrow_forwardTensile engineering stress-strain curves through failure are depicted below. Which specimen features the highest toughness? Engineering Stress, MPa 1800- 1600- 1400- 1200- 1000- 800- 600- 400- 200- Ol 0 Aluminum Alloy 2024-T81 0.04 0.08 Stainless Steel (18-8) 1340 Steel, Water-Quenched & Tempered at 370 C Magnesium 0.12 Structural Steel (Mild Steel) Engineering Strain 0.16 1340 Steel, Water-Quenched & Tempered at 370°C Aluminum Alloy 2024-T81 Structural Steel (Mild Steel) Stainless Steel (18-8) Magnesium 0.20 0.24arrow_forward
- Between 1. Nominal (engineering) stress and true stress and 2. True strain and engineering strain which is always less than the other?arrow_forwardWhich one of the following is the correct definition of ultimate tensile strength, as derived from the results of a tensile test on a metal specimen: O the stress encountered when the stress strain curve transforms from elastic to plastic behavior the maximum load divided by the final area of the specimen the maximum load divided by the original area of the specimen O the stress observed when the specimen finally failsarrow_forwardHow is the nominal or engineering strain found directly from the strain gage?arrow_forward
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