Fracture and Fatigue Calculator.xls

Purpose of calculation
Determine stress that will cause fast fracture of a cracked aluminium beam under bending loads.
Determine the number of constant load cycles until the beam will suffer a fast fracture.

Calculation Reference
https://www.efatigue.com/constantamplitude/stressintensity/
https://www.efatigue.com/probabilistic/background/crackgrowth.html

Calculation Validation
Cell formulae checked using XLC.
Procedure
Input
Crack length
Applied Stress
Calculate:
Crack Correlation factor function
Stress intensity factor.
Determine the likelihood of fast fracture
Fracture toughness of material
Fracture ratio
Consider Fatigue Crack Growth Rate
Crack growth Intercept
Crack growth Exponent
Threshold Stress intensity for crack growth
Crack growth per cycle
Procedure for producing Crack growth Curve
1 Use Excel Goal seek to change crack size until fracture ratio = 100%.
2 This is the critical size for fast fracture, and make a note of the number.
3 Put the crack size back to initial crack size.
4 Use goal seek again to change the block size (cell AN30) until the final crack size (cell BG61) equals the critical crack size.
5 The number of cycles to failure is in Cell BG63.
Note: The calculation considers 20 block cycles - it is more accurate if you consider more.

Calculation Reference
Fracture mechanics
Mechanics and Mechanisms of Fracture
Fatigue and Fracture