Patent Number: 
Section: claims

1. A method to analyze fatigue damage values of wheels each to be installed at a number of axle positions on a vehicle, comprising:(a) simulating installations by randomly determining the axle positions of each wheel on the vehicle;(b) determining at each of the axle positions for each wheel a fatigue damage value for each of a plurality of critical locations at the wheel during an installation;(c) storing the fatigue damage values of the critical locations for each installation;(d) summing the respective retained fatigue damage value for each critical location to determine a respective total fatigue damage value;(e) repeating (a), (b), (c) and (d) a number of times to obtain at each of the critical locations a distribution of total fatigue damage values; and(f) determining whether or not at least a subset of the total fatigue damage values at each of the critical locations exceeds a respective threshold total fatigue damage value. 2. A method as defined in claim 1, wherein the simulated installations of the wheel substantially equals an expected number of installations of the wheel. 3. A method as defined in claim 1, further including determining the number of installations of the wheel on the vehicle. 4. A method as defined in claim 3, wherein the number of installations is determined by approximately the number of tires that may be used by the wheel during a service life of the wheel. 5. A method as defined in claim 4, wherein a tire life of a tire may be one of a constant value or a value selected from a normal distribution of tire lives. 6. A method as defined in claim 1, wherein the critical locations are provided by determining locations subject to critical fatigue stress at the wheel. 7. A method as defined in claim 6, wherein repeating (a), (b), (c) and (d) continues until the fatigue damage value at each of the critical locations for a current installation is substantially the same as the fatigue damage value of the corresponding critical location for an immediately prior installation. 8. A method as defined in claim 1, further comprising determining, at each of the critical locations at the wheel, the fatigue damage value corresponding to a preload value of fasteners of the wheel. 9. A method as defined in claim 8, wherein the fasteners of the wheel are presumed to have the same preload value. 10. A method as defined in claim 9, wherein the preload value is determined for each of the simulated installations. 11. A method as defined in claim 8, wherein determining a preload value comprises randomly selecting one of a plurality of preload values to obtain a corresponding fatigue damage value, wherein the random selection of the preload value uses one of a uniform probability of selection or a highest probability of selection. 12. A method as defined in claim 1, wherein the subset comprises at least 95% of the total fatigue damage values. 13. An apparatus to analyze fatigue damage values of wheels each to be installed at a number of axle positions on a vehicle, comprising:(a) an axle position generator to simulate random determinations of the installed axle positions of each wheel on the vehicle;(b) a fatigue damage value generator to obtain the positions of each wheel from the axle position generator to determine at each of the axle positions for each wheel a fatigue damage value for each of a plurality of critical locations at the wheel during an installation, to store the fatigue damage values of the critical locations for each installation, to sum the respective retained corresponding fatigue damage value for each critical location to determine and store a respective total fatigue damage value, and to store total fatigue damage values of a distribution of respective total fatigue damage values obtained from repeating the summing of the fatigue damage values, and(c) a comparator to determine whether or not at least a subset of the respective total fatigue damage values at a critical location exceeds a respective threshold total fatigue damage value for the wheel. 14. The apparatus as defined in claim 13, further comprising an installation quantity value generator to determine a number of installations of the wheel to be simulated on the vehicle. 15. The apparatus as defined in claim 14, further comprising a tire life value generator to determine a life of a tire to be used on the wheel. 16. The apparatus as defined in claim 13, further comprising a wheel life value generator to determine a life of a wheel to be used on the vehicle. 17. The apparatus as defined in claim 13, further comprising a torque preload value generator to determine a preload value of fasteners of the wheel. 18. The apparatus as defined in claim 17, wherein a preload value is determined for each of the simulated installations. 19. The apparatus as defined in claim 17, wherein the fatigue damage value determined for each of the plurality of critical locations at the wheel during an installation is a function of the preload value. 20. A computer-readable medium storing computer readable instructions which, when executed by a computer, causes the computer to:(a) simulate installations by randomly determining the axle positions of each wheel on the vehicle;(b) determine at each of the axle positions for each wheel a fatigue damage value for each of a plurality of critical locations at the wheel during an installation;(c) store the fatigue damage values of the critical locations for each installation;(d) sum the respective retained fatigue damage value for each critical location to determine a respective total fatigue damage value;(e) repeat (a), (b), (c) and (d) a number of times to obtain at each of the critical locations a distribution of total fatigue damage values; and(f) determine whether or not at least a subset of the total fatigue damage values at each of the critical locations exceeds a respective threshold total fatigue damage value.