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                                                                                     Failures Resulting from Static Loading  215
                       Figure 5–2

                       Impact failure of a lawn-mower
                       blade driver hub. The blade
                       impacted a surveying pipe
                       marker.













                       Figure 5–3

                       Failure of an overhead-pulley
                       retaining bolt on a weightlifting
                       machine. A manufacturing
                       error caused a gap that forced
                       the bolt to take the entire
                       moment load.
































                       Figure 5–4
                       Chain test fixture that failed in one cycle. To alleviate complaints of excessive wear, the manufacturer decided to
                       case-harden the material. (a) Two halves showing fracture; this is an excellent example of brittle fracture initiated
                       by stress concentration. (b) Enlarged view of one portion to show cracks induced by stress concentration at the
                       support-pin holes.
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