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PowerPoint ® Presentation Chapter 3 Mechanical Testing Mechanical Testing Dynamic Mechanical Tests Static Mechanical Tests Hardness Testing.

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Presentation on theme: "PowerPoint ® Presentation Chapter 3 Mechanical Testing Mechanical Testing Dynamic Mechanical Tests Static Mechanical Tests Hardness Testing."— Presentation transcript:

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2 PowerPoint ® Presentation Chapter 3 Mechanical Testing Mechanical Testing Dynamic Mechanical Tests Static Mechanical Tests Hardness Testing

3 Chapter 3 Mechanical Testing A mechanical force or load may be applied using five different methods.

4 Chapter 3 Mechanical Testing Longitudinal and transverse test specimens taken from cold-rolled plate material exhibit different mechanical properties.

5 Chapter 3 Mechanical Testing There are four classifications of cyclic stresses in fatigue. A cycle is each complete application of the stress.

6 Chapter 3 Mechanical Testing The magnitude of the fatigue limit depends on the stress repetition pattern, which is plotted on an S-N curve.

7 Chapter 3 Mechanical Testing Metal tested at a low strain rate is ductile compared with the same metal tested at a high strain rate.

8 Chapter 3 Mechanical Testing A universal pendulum impact tester can perform both the Charpy and Izod impact tests.

9 Chapter 3 Mechanical Testing The V-notch is the most common Charpy and Izod impact test specimen.

10 Chapter 3 Mechanical Testing The swing of the pendulum after it strikes the test specimen indicates the energy absorbed on impact.

11 Chapter 3 Mechanical Testing The main differences between the Charpy and Izod impact tests are the position of the notch and the method of support of the test specimen.

12 Chapter 3 Mechanical Testing The sharper the inflection of the curve, the easier the estimation of the NDT temperature.

13 Chapter 3 Mechanical Testing The drop weight test is more reliable than the Charpy when determining ductility.

14 Chapter 3 Mechanical Testing A universal testing machine can be mechanical or hydraulic.

15 Chapter 3 Mechanical Testing A fillet is used on the tensile test specimen to minimize stress concentrations, and the gauge marks are always an equal distance from the center of the length of the reduced section.

16 Chapter 3 Mechanical Testing A variety of tensile test specimen ends are used to ensure secure and uniform gripping by the test machine.

17 Chapter 3 Mechanical Testing An extensometer measures the extension of elongation of the tensile test specimen.

18 Chapter 3 Mechanical Testing The load-extension curve shows load and extension limits for metals.

19 Chapter 3 Mechanical Testing Increased gauge length and reduced diameter at the narrowest point are measured and used to calculate the percent elongation and percent reduction in area.

20 Chapter 3 Mechanical Testing The yield strength, or 0.2% offset, is calculated by measuring the stress that causes a specific permanent strain (usually 0.2%).

21 Chapter 3 Mechanical Testing Percent elongation is calculated from the gauge length.

22 Chapter 3 Mechanical Testing The guided bend test is an inexpensive and rapid method to check the quality of a weld.

23 Chapter 3 Mechanical Testing Cupping tests provide an indication of the formability of sheet metal.

24 Chapter 3 Mechanical Testing A torsion testing machine is used for determining a metals resistance to shear.

25 Chapter 3 Mechanical Testing A tropometer is used to measure the degree of twist during a torsion test.

26 Chapter 3 Mechanical Testing The scleroscope hardness tester uses the height of rebound of a diamond-tipped hammer from the test specimen surface to determine hardness.

27 Chapter 3 Mechanical Testing The Equotip metal hardness tester can be used in five positions.

28 Chapter 3 Mechanical Testing The Brinell hardness tester applies a load for a specific period of time and causes an indentation that is used to calculate hardness.

29 Chapter 3 Mechanical Testing Soft or hard metals require careful measurement of their indentations in the Brinell test.

30 Chapter 3 Mechanical Testing The Rockwell test uses two loads, a minor and a major, that are applied sequentially to determine hardness.

31 Chapter 3 Mechanical Testing The Rockwell designation system consists of the hardness number followed by HR, which is followed by the letter indicating the specific Rockwell scale.

32 Chapter 3 Mechanical Testing The microhardness measured by a microhardness tester is always higher than the bulk surface hardness.


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