HW_CH6

HW_CH6 - S-N Diagram for Steel for Problem 6-2c FIGURE 6-2c...

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Unformatted text preview: S-N Diagram for Steel for Problem 6-2c FIGURE 6-2c 1 . 10 3 1 . 10 4 1 . 10 5 1 . 10 6 1 . 10 7 1 . 10 8 10 100 1 . 10 3 S' f N ( ) ksi N N 10 3 10 5 , 10 8 .. = 6. Plot the S-N curve over the range S' f N ( ) a N b return N 10 6 < if S' e otherwise = 5. To draw the S-N graph over the range 10 3 <= N <= 10 8 , define a piecewise continuous function. a 194.4 ksi = a S m 10 3 ( 29 b = b 0.0851- = b 1 z log S m S' e = 4. Determine the constants a and b from equations (6.10c) and (6.10a). From Table 6-5, for N = 10 6 , z 3.000- = S' f a N b 3. The equation for the S-N curve in the HCF region is given by equation (6.10a): S m 108.0 ksi = S m 0.9 S ut = 2. Using equation (6.9), calculate the fatigue strength at N = 10 3 cycles. S' e 60.0 ksi = S' e 0.5 S ut return S ut 200 ksi if 100 ksi otherwise = 1. Using equation (6-5a), calculate the uncorrected endurance limit. Solution: See Mathcad file P0602a. S ut 120 ksi = Tensile strength Given: ksi 10 3 psi = Units: Statement: For the strength data in row a in Table P6-2, calculate the uncorrected endurance limit and draw the strength-life ( S-N ) diagram for the material, assuming it to be steel. PROBLEM 6-2c S-N Diagram for Aluminum for Problem 6-4c FIGURE 6-4c 1 . 10 3 1 . 10 4 1 . 10 5 1 . 10 6 1 . 10 7 1 . 10 8 10 100 1 . 10 3 S' f N ( ) ksi N N 10 3 1.0110 5 , 10 8 .. = 6. Plot the S-N curve over the range S' f N ( ) a N b = 5. To draw the S-N graph over the range 10 3 <= N <= 10 8 , a 269.58 ksi = a S m 10 3 ( 29 b = b 0.1324- = b 1 z log S m S' f5E8 = 4. Determine the constants a and b from equations (6.10c) and (6.10a). From Table 6-5, for N = 5E8 , z 5.699- = S' f a N b 3. The equation for the S-N curve in the HCF region is given by equation (6.10a): S m 108.0 ksi = S m 0.9 S ut = 2. Using equation (6.9), calculate the fatigue strength at N = 10 3 cycles. S' f5E8 19.0 ksi = S' f5E8 0.4 S ut return S ut 48 ksi if 19 ksi otherwise = 1. Using equation (6-5c), calculate the uncorrected fatigue strength at 5E8 cycles. Solution: See Mathcad file P0604a. S ut 120 ksi = Tensile strength Given: ksi 10 3 psi = Units: Statement: For the strength data in row a in Table P6-2, calculate the uncorrected fatigue strength at 5E8 cycles and draw the strength-life ( S-N ) diagram for the material, assuming it to be an aluminum alloy. PROBLEM 6-4c 1. Using equation (6-5a), calculate the uncorrected endurance limit. S' e 0.5 S ut return S ut 200 ksi if 100 ksi otherwise = S' e 55.0 ksi = 2. Calculate the endurance limit modification factors for a nonrotating round rod. Load C load 1 return load "bending" if 1 return load "torsion" if 0.7 return load "axial" if = C load 1 = Size d equiv d = C size 0.869 d equiv in 0.097- = C size 0.812 = Surface A 1.34 return surface "ground" if 2.70 return surface "machined" if 2.70 return surface "cold_rolled" if...
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HW_CH6 - S-N Diagram for Steel for Problem 6-2c FIGURE 6-2c...

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