Strength of Materials: Introduction

INTRODUCTION

Whenever the object is subjected to the application of external load, the dimensions of the object changes due to the deformation effect in the x, y and z directions of the applied load. But the interlinking bond between the molecules of the object offer some resistance in the opposite direction to the direction of the applied load, this resistance offered by the object towards the external load is called as strength of material.

FIG 1

                                                                  FIG 2

                                                                     FIG 3

FIG 4

Figure 1 shows the interlinking of the bond between the molecules before the application of the load. As the load of magnitude P is applied, the equivalent intermolecular bond offers the resistance of magnitude W in the opposite direction to the applied force P up to the limiting extent (shown in figure 2).Further with the increment in the magnitude of the applied load P, the resisting force due to the interlinking of the bond exceeds the limit and thereby weakens the bond strength which results in decremental effect of resisting force towards the application of load and leads to the initiation of cracks on the surface of the object (shown in figure 3).With the continued increase in the magnitude of the applied load, the bond strength still weakens and there by the resisting force decreases , propagation of cracks increases which therefore results in fracture of the object(shown in figure 4).