CONCLUSION Using limited displacement measurements collected experimentally, accurate estimation of dynamic stress-strain was shown. The technique used to estimate dynamic stress strain was a full-field technique which involved use of expansion algorithm to obtain full-field displacements and then using the full-field displacements to obtain full-field dynamic stressstrain through stress recovery process. Dynamic stress-strain information at 3112 locations in the structure was successfully obtained from only 7 displacement measurements made experimentally due to impulsive excitation. Several cases were investigated to show the accuracy and robustness of the expansion procedure. The expansion procedure will produce accurate results provided that there are a sufficient set of orthogonal mode shapes to span the space for the solution; this requires that a sufficient number of modes that participate in the response be included in the expansion process. Successful estimation of dynamic stress strain from limited experimental data was shown without the need for estimating the boundary conditions or loads. REFERENCES [1] Chipman, C., “Expansion of Real Time Operating Data”, Master’s Thesis, University of Massachusetts Lowell, May 2009 [2] Chipman, C., Avitabile, P., “Expansion of Real Time Operating Data for Improved Visualization”, Proceedings of the Twenty-Sixth International Modal Analysis Conference, Orlando, FL, Feb 2008 [3] Chipman, C., Avitabile, P., “Expansion of Transient Operating Data”, Proceedings of the Twenty- Seventh International Modal Analysis Conference, Orlando, FL, Feb 2009 [4] Pingle, P., Avitabile, P., “Prediction of Full Field Dynamic Stress/Strain from Limited Sets of Measured Data”, Proceedings of the Twenty-Eight International Modal Analysis Conference, Jacksonville, FL, Feb 2010 [5] Pingle, P., Avitabile, P., Niezrecki, C., “Real Time Operating Data Expansion for Dynamic Stress and Dynamic Strain Fatigue Accumulation”, The 7th International Workshop on Structural Health Monitoring, Stanford University, Stanford, CA, September 9-11, 2009 [6] Vandepitte, D., Sas, P., “Case study of fracture of a mechanical component due to resonance fatigue”, Mechanical Systems and Signal Processing, Volume 4, Issue 2, Pages 131-143, March 1990 [7] De Langhe, K., Vandepitte, D., Sas, P., “A combined dynamic-static finite element model for the calculation of dynamic stresses at critical locations”, Computers & Structures, Volume 65, Issue 2, Pages 241-254, October 1997 [8] Huang, L., Agarwal, H., Borowski, V., “Durability analysis of a vehicle body structure using modal transient methods”, Proceedings of the International Modal Analysis Conference - IMAC, v 1, p 407-414, 1997 [9] Tucchio, M., Epstein, H., Craney, III K., “An experimental-modal computational technique to find dynamic stresses”, Computers and Structures, Volume 24, Issue 4, Pages 559-569, 1986 [10] Kelly, N., Sutherland, H., "Damage Estimates from Long-Term Structural Analysis of a Wind Turbine in a U.S. Wind Farm Environment",1997 ASME Wind Energy Symposium, AIAA/ASME, pp. 170-179, 1997 [11] Veers, P., Sutherland, H., Ashwill, T., "Fatigue Life Variability and Reliability Analysis of a Wind Turbine Blade", Proceedings: Probabalistic Mechanics and Structural and Geothermal Reliability, Y.K. Lin ed., ASCE, July 1992 [12] Veers, P.,Lange, C., Wintersten, S., "FAROW: A Tool For Fatigue and Reliability of Wind Turbines", Proceedings of WindPower '93, AWEA, July 1993 [13] Lange, C., Kumar, S., "FITTING: A Subroutine to Fit Four Moment Probability Distributions to Data", SAND943039 [14] Manuel, L., Kashef, T., Winterstein, S., "Moment-Based Probability Modelling and Extreme Response Estimation The FITS Routine Version 1.2", SAND99-2985 [15] Manuel, L., Veers, P., Winterstein, S., "Parametric Models For Estimating Wind Turbine Fatigue Loads For Design", 2001 ASME Wind Energy Symposium, AIAA/ASME, 2001 [16] Veers, P., Winterstein, S., "Application of Measured Loads to Wind Turbine Fatigue and Reliability Analysis", 1997 ASME Wind Energy Symposium, AIAA/ASME, 1997 [17] Veers, P., Butterfield, S., "Extreme Load Estimation for Wind Turbines: Issues and Opportunities for Improved Practice”, 2001 ASME Wind Energy Symposium, AIAA/ASME, 2001 [18] Zhu, B., Xiao, J., “Study on calculation method and its application for dynamic stress of steam turbine blade”, American Society of Mechanical Engineers, Power Division (Publication) PWR, v 34, p 2/-, 1999 216
RkJQdWJsaXNoZXIy MTMzNzEzMQ==