Page 339 - statbility for masters and mates
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Bending of beams 327
Fig. 40.2
the section on the right-hand side of the material tends to move down- wards, as shown in Figure 40.2(a), the stress is considered to be positive, and when the direction of a stress is such that the section on the right-hand side tends to move upwards as shown in Figure 40.2(b), the shearing stress is considered to be negative.
