SEDL / STP / STP1231-EB / STP13963S

Applying Contemporary Life Assessment Techniques to the Evaluation of Urban Bus Structures

de Freitas, MM
Professors, Center of Mechanics and Materials, Technical University of Lisbon (CEMUL), Portuguese National Institute of Scientific Research (INIC), Instituto Superior Técnico, Lisboa Codex,

Maia, NM
Professors, Center of Mechanics and Materials, Technical University of Lisbon (CEMUL), Portuguese National Institute of Scientific Research (INIC), Instituto Superior Técnico, Lisboa Codex,

Montalvão e Silva, J
Professors, Center of Mechanics and Materials, Technical University of Lisbon (CEMUL), Portuguese National Institute of Scientific Research (INIC), Instituto Superior Técnico, Lisboa Codex,

Silva, JD
Professors, Center of Mechanics and Materials, Technical University of Lisbon (CEMUL), Portuguese National Institute of Scientific Research (INIC), Instituto Superior Técnico, Lisboa Codex,

Pages: 15    Published: Jan 1994

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Abstract

The authors present a study where personal computers are used to analyze the structural behavior of urban buses and to obtain in-service loading histories. Theoretical analysis, previously performed and based on finite element techniques and static loads, allowed the correct choice of ten points, in a typical bus structure, where strain gages were bonded to measure the strain history under real working conditions. The measured data were analyzed using the rainflow counting method to obtain the characteristic loading and generate a typical service spectrum for a bus structure. Results for ground transport vehicles were found to be similar to those obtained by other authors. The fatigue crack growth behavior of the steel used in the bus structures under analysis was determined experimentally and the data thus obtained were used to calculate the fatigue crack growth behavior of the bus structural elements. Finally, the fatigue life of these elements, due to the loading spectrum previously obtained, was predicted using a computer-aided fatigue crack growth calculation based on Forman's law of crack propagation.