STRESS AND STRAIN. 



21 



instead of the shears of Figure 5, at the boundaries there will 

 only exist the shears indicated in Figure 6, the missing 

 shears having become converted into various direct stresses or 

 shears in other directions. 



FIGURE 6 



The effect of this is to produce near the bounding surface 

 a tendency to rotation of the elements and a warping of oth- 

 erwise plane interior surfaces as indicated in Figure 7. 



rxrm tttttt 



-4- 



^M)17fa 



FIGURE 7 



