PIPE AS-WATER 1408485 - Caterpillar

Installing Reinforcing Plates
Machine components fail primarily because of a localized overstressed condition. This overstressing is caused either by overloading, which stretches, compresses or bends the member, or by repeated flexing which cracks the member without visible bending. The former may occur, for example, in a track roller frame, the latter in a scraper gooseneck. In either case, the stresses can be reduced by properly applying reinforcements to the weak section. Improper application may have the opposite effect. High stresses usually occur at definite, predictable locations in machine members, although the locations are not always apparent until a failure occurs.The understanding and application of several basic rules will help in the successful design and installation of reinforcing plates: Rule 1 - Avoid sudden changes in cross-sectional area. Notches, sharp corners, and abrupt changes in area give rise to points of stress concentration. Reinforcements should be designed to enable loads to be transmitted smoothly through the reinforcement and from the reinforcement to the machine component (Figure 54). Notches and cracks should be filled with weld metal; corners should be curved with a generous radius; changes in width or thickness of plates should be gradual; ends should be tapered.
Figure 54 - Changes in cross sectional area must be made smoothly and gradually.Several examples of well designed reinforcement plates are shown in Figure 55. Note the tapered ends and rounded corners. In most cases, tapered plates add the same strength to beams subjected to bending stresses as rectangular plates do (Figure 56). The tapered plates weigh about half as much as rectangular plates and require no more time to install.
Figure 55 - Properly designed reinforcements have tapered ends and rounded corners.
Figure 56 - Rectangular reinforcing plates add no more strength than tapered plates. Rule 2 - Place reinforcements as far as possible from the neutral axis for bending loads. The neutral axis of a beam is located on a line of zero stress, which is usually at or near the center of the beam. Reinforcing plates of a given thickness will be most effective when placed as far as possible from the neutral axis (Figure 57). Note that plates added to the top and bottom of a beam parallel to the neutral axis add considerable more strength than plates of the same thickness added to the sides of the beam.
Figure 57 - Bending Load Reinforcements Rule 3 - Use a circular or box section for torsional loads. Reinforcements for shafts subjected to torsional stresses should be continuous around the shaft and should run the full length that is in torsion. (Figure 58). Square sections should be reinforced by adding plates on all sides. Rectangular sections are strengthened by adding plates to the opposite sides that are closest together. I-beams, channels and angles should be reinforced in such a manner that the final section is boxed. In all cases, the circular or boxed section is much stronger in torsion and is preferred for torsional loads.
Figure 58 - Torsional Load Reinforcements Rule 4 -