Page 230 - Marks Calculation for Machine Design

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–10 STRENGTH OF MACHINES
(10,–4)
σ
–10 3.5 15
(–3,4)
10 Scale: 1 kpsi × 1 kpsi
t (2q ccw)
FIGURE 5.17 Connect points to find average stress (σ avg ).

Usedistancefromtheaveragestresstoeitherpointasaradiusanddrawa circle(Fig.5.18).

–10
Radius
(10,–4)
s
–10 3.5 15
(–3,4)

10 Scale: 1 kpsi × 1 kpsi
t (2q ccw)

FIGURE 5.18 Draw circle.
Graphically from Fig. 5.19, the maximum principal stress is (11), and the minimum
principal stress is (−4). The radius of the circle is the maximum shear stress, and scales to
(7.5). These are the same values found in Example 5 in Sec. 5.2.

–10

(10,–4)
–4 11 σ
–10 3.5 15
(–3,4) 7.5

10 Scale: 1 kpsi×1 kpsi
t (2q ccw)
FIGURE 5.19 Principal stresses and radius of circle.