You have been hired by the quality control section of Stanle

You have been hired by the quality control section of Stanley and you have been tasked with determining the optimal material for the manufacture of hammers. As you know, hammers are constantly subjected to deformation during their usage and you have determined that testing the fatigue of materials is the best way about it. You have carried out fatigue tests on two materials and have established the plot below.

a. What do quality control engineers do?

b. What are the maximum and minimum stress levels that have been subjected by the two materials?

c. Assuming the materials in question have shown failure at the indicated spot, which of the two would choose for the manufacture of a hammerhead?

Fatigue 515 510 505 500 2 495 490 485 0 0.5 1.5 2 2.5 3.5 time in hours

Solution

a.Quality control engineers is reponsible for the quality of the job manufactured subjected to established codes and standards. In the above example the selection of material depends on the job which has to be deformed/worked with the hammer. The strenght of the hammer material should be generally higher than that of the work piece. Quality enginners will take care of the above strength or the stresses it withstand without deformation. They carry various mechanical tests viz., destructive and non destructive tests to assess the quality of the hammer material. In this problem the test is fatique test.

b.Maximum and minimum stress levels subjected by the two materials are 510 kPa and 490kPa respectively.

c. As shown in figure the material A failed at 500kPa and material B failed at 510kPa. As a design engineer one has to choose the material which is withstanding more case. In this problem one has to choose material B when compared to material A.