Science and engineering materials askeland pdf

The minimum volume fraction of carbon fibers needed to give a composite modulus of The volume fraction of epoxy remaining is 0. An area of 0. Although the carbon fibers are the most expensive, they permit the lightest weight and the lowest material cost strut. This calculation does not, however, take into consideration the costs of manufacturing the strut.

Our design, therefore, is to use a 0. Producing Laminar Composites - a roll bonding, b explosive bonding, c coextrusion, and d brazing. Cladding - A laminar composite produced when a corrosion-resistant or high-hardness layer of a laminar composite formed onto a less expensive or higher- strength backing.

Bimetallic - A laminar composite material produced by joining two strips of metal with different thermal expansion coefficients, making the material sensitive to temperature changes.

The sandwich combines overall light weight with excellent stiffness. Honeycomb - A lightweight but stiff assembly of aluminum strip joined and expanded to form the core of a sandwich structure.

The corrugated sheets are joined together with adhesive and then cut to the desired thickness. Open navigation menu. Close suggestions Search Search. User Settings. Skip carousel. Carousel Previous. Carousel Next. What is Scribd? Explore Ebooks. Bestsellers Editors' Picks All Ebooks. Explore Audiobooks. Bestsellers Editors' Picks All audiobooks. Explore Magazines. Editors' Picks All magazines. Explore Podcasts All podcasts. Difficulty Beginner Intermediate Advanced.

Explore Documents. Askeland Chapter. Uploaded by juegyi. Original Title Askeland Chapter Did you find this document useful? Is this content inappropriate? Report this Document. Flag for inappropriate content. The science-based approach highlights how materials change with time and due to loading and environment - a key concept that is often overlooked when using charts and databases to select materials.

Please select an option. View More Purchase Options. The Science and Engineering of Materials 7th Edition. Donald R. View as Instructor. What time will be required to give us a similar carburizing treatment? By heating the alloy to oC for 3 hours, diffusion of zinc helps to make the composi- tion more uniform. What temperature would be required if we wished to perform this homogenization treatment in 30 minutes? Which will limit the rate at which sintering can be done: diffusion of mag- nesium ions or diffusion of oxygen ions?

What time will be required at the lower temperature? Solution: Diffusion of oxygen is the slower of the two, due to the larger ionic radius of the oxygen. The alloy is then heated to various temperatures, permitting grain growth to occur. The times required for the grains to grow to a diameter of 0.

Does this correlate with the diffu- sion of zinc in copper? Hint: Note that rate is the reciprocal of time. At oC, h are required to obtain the same degree of bonding, and at oC, bonding requires years. What is the activation energy for the diffusion bonding process? Does it appear that diffusion of gold or diffusion of silver controls the bonding rate? Determine a whether the wire will plastically deform and b whether the wire will experience necking. Determine whether the bar will plastically deform and whether the bar will experience necking.

Because s is greater than the tensile strength of MPa, the wire will also neck. Express your answer in pounds and Newtons. Calculate the modulus of elasticity, both in GPa and psi. The polymer has a modulus of elasticity of , psi. What force is required to stretch the bar elastically to If the aluminum has a yield strength of MPa, what is the min- imum width of the plate? To account for the elastic strain, what should be the diameter of the opening? The opening in the die must be smaller than the final diameter.

What is the length of the cable during lifting? Plot the data and calculate the 0. Plot the data and calculate a the 0. The deflection of the center of the bar is measured as a function of the applied load. The data are shown below.

Determine the flexural strength and the flexural modulus. Force Deflection Stress lb in. The flexural strength is the stress at fracture, or 24, psi. The flexural modulus can be calculated from the linear curve; picking the first point as an example: FL3 Determine the length and diameter of the bar when a lb load is applied. Determine the applied load, using the data in Table 6—3.

When a force of lb is applied, the specimen deflects 0. Calculate a the flex- ural strength and b the flexural modulus, assuming that no plastic deformation occurs. The sam- ple breaks when a deflection of 0. Calculate a the force that caused the fracture and b the flexural strength.

The flexural modulus for silicon carbide is GPa. Assume that no plastic deformation occurs. Solution: a The force F required to produce a deflection of 0. The polymer part is 2 cm wide, 0. If the flexural modulus is 6. Will the polymer fracture if its flexural strength is 85 MPa? Solution: a The minimum distance L between the supports can be calculated from the flexural modulus. A bar of alumina 0. Determine the amount of deflection at the moment the bar breaks, assuming that no plastic deformation occurs.

Determine the Brinell hardness number HB of the metal. Estimate the tensile strength of the steel. Plot the data and determine a the transition temperature defined by the mean of the absorbed ener- gies in the ductile and brittle regions and b the transition temperature defined as the temperature that provides 10 J absorbed energy.

Plot the transition temperature versus silicon content and discuss the effect of silicon on the toughness of the cast iron. What would be the maximum silicon allowed in the cast iron if a part is to be used at 25oC? Test temperature Impact energy J oC 2. If the part is to be used at 25oC, we would want a maximum of about 2. Solution: FCC metals do not normally display a transition temperature; instead the impact energies decrease slowly with decreasing temperature and, in at least some cases such as some aluminum alloys , the energies even increase at low temperatures.

The FCC metals can obtain large ductili- ties, giving large areas beneath the true stress-strain curve. Which part is expected to have the higher toughness? Solution: Parts produced by powder metallurgy often contain considerable amounts of porosity due to incomplete sintering; the porosity provides sites at which cracks might easily nucleate. Parts machined from solid steel are less likely to contain flaws that would nucleate cracks, therefore improving toughness.

Would you expect these alloys to be notch-sensitive in an impact test? Would you expect these alloys to have good toughness? Explain your answers. Solution: The sharp-edged plates of the brittle silicon may act as stress-raisers, or notches, thus giving poor toughness to the alloy.

Consequently this type of alloy is expected to have poor toughness but is not expected to be notch sensitive. Suppose that fibers of sili- con carbide SiC , another brittle ceramic with low toughness, could be embedded within the alumina.

Would doing this affect the toughness of the ceramic matrix composite? These materials are discussed in later chapters.

Solution: The SiC fibers may improve the toughness of the alumina matrix. The fibers may do so by several mechanisms. By introducing an interface between the fibers and the matrix , a crack may be blocked; to continue growing, the crack may have to pass around the fiber, thus increasing the total energy of the crack and thus the energy that can be absorbed by the material.

Or extra energy may be required to force the crack through the interface in an effort to continue propagating. In addition, the fibers may begin to pull out of the matrix, particularly if bonding is poor; the fiber pull-out requires energy, thus improving toughness. Finally, the fibers may bridge across the crack, helping to hold the material together and requiring more energy to propagate the crack.

The plane strain fracture toughness of the composite is 45 MPa m and the tensile strength is MPa. Will the flaw cause the composite to fail before the tensile strength is reached?

Any failure of the ceramic should be expected due to the massive overload, not because of the presence of the flaws. Observation of the fracture surface indi- cates that fracture began at the surface of the part. Estimate the size of the flaw that initiated fracture.

Determine the plane strain fracture toughness of the polymer. To be sure that the part does not fail, we plan to assure that the maximum applied stress is only one third the yield strength.

We use a nondestructive test that will detect any internal flaws greater than 0. Our nondestructive test can detect flaws as small as 0.

Thus our NDT test is not satisfactory. Assuming that the maximum tensile and compressive stresses are equal, determine the maximum load that can be applied to the end of the beam. See Figure 7— Solution: The stress must be less than the endurance limit, 60, psi.

What is the maximum permissible load that can be applied? Solution: From the figure, we find that the fatigue strength must be 22 MPa in order for the polymer to survive one million cycles. The bar must survive for at least cycles. What is the mini- mum diameter of the bar? Solution: From the figure, we find that the fatigue strength must be 35, psi in order for the aluminum to survive cycles.

How many hours will the part survive before breaking? What is the fatigue strength, or maximum stress amplitude, required? What are the maximum stress, the minimum stress, and the mean stress on the part during its use? What effect would the frequency of the stress application have on your answers?

Solution: From the figure, the fatigue strength at one million cycles is 22 MPa. A high frequency will cause heating of the polymer. As the temperature of the polymer increases, the fatigue strength will decrease. If the applied stress is not reduced, then the polymer will fail in a shorter time. Calculate the growth rate of a surface crack when it reaches a length of 0. It is to survive for cycles before failure occurs.

Calculate a the size of a surface crack required for failure to occur and b the largest initial surface crack size that will permit this to happen. The largest surface cracks initially detected by nondestructive testing are 0. If the critical fracture toughness of the polymer is 2 MPa m , calculate the number of cycles required before failure occurs.

Hint: Use the results of Problem 7— A copper speci- men creeps at 0. If the creep rate of copper is dependent on self-diffusion, determine the creep rate if the temperature is oC. The initial stress applied to the material is 10, psi.

The diameter of the specimen after fracture is 0. Solution: 0. Solution: Plots describing the effect of applied stress on creep rate and on rupture time are shown below. How many days will the bar survive without rupturing at oC? What is the maximum load that can be applied? Calculate the minimum diameter of the bar. What is the maximum operating temperature? What is the maximum allowable temperature? Thus The following measurements are made in the plastic region: Change in Force lb Gage length in.

The following measurements are made. Determine the strain harden- ing exponent for the metal. The bar, which has an initial diameter of 1 cm and an initial gage length of 3 cm, fails at an engineering stress of MPa. After fracture, the gage length is 3. No necking occurred. Essentials of materials science and engineering by Donald R Askeland.

Much of this work is interdisciplinary, providing data for creating computer models and validation of such models. Much of this work is interdisciplinary, materoals data for creating computer models and validation of such models. AskelandWendelin J. User Review — Flag as inappropriate Nice book having many topics according to mms please read every one. Please create a new list with eonald new name; move some items to a new or existing list; or delete some items.

Additional work has concentrated on lost foam casting, permanent mold casting, and investment casting. Looking for beautiful books? Search WorldCat Find items in libraries near you.