On the use of thermographic method to measure fatigue limits

Abstract

Traditional fatigue limit measurements are expensive and time consuming, requiring a large number of specimens and a long time to be completed. An alternative approach is used in this work to obtain the fatigue limit of a cold drawn steel, in a rotating bending machine, by monitoring temperature variations induced by different load range levels in just a few specimens. Comparisons with Dixon's traditional up-and-down method confirm that this thermographic approach is indeed a much more efficient, faster, and cheaper method to obtain fatigue limits.

Preface to the special issue of the International Symposium on Solid Mechanics (MecSol 2017)

“…• Structural Reliability Methods and Reliability-Based Design Optimization: Multi-objective optimization (Passos and Luersen, 2018) and experimental crack identification (Oliveira Filho et al, 2018). • Multiaxial and Fretting Fatigue: identification of fatigue limits and continuum damage mechanics (Castro and Bemfica, 2018), stress-life curves for alloy steels (Duran et al, 2018) and assessment of fatigue limits (Bandeira et al, 2018).…”

Influence of Transformation Temperature on the High‐Cycle Fatigue Performance of Carbide‐Bearing and Carbide‐Free Bainite

“…[22][23][24][25] Although determination of fatigue limit via traditional methods might be more reliable, it is still expensive, time-consuming, and requires a large amount of specimens. [26,27] In recent years, multiple studies are conducted for rapid determination of fatigue limit (or fatigue life) based on temperature evolution of specimens during fatigue testing correlated with fatigue damage of material, which is used to estimate the fatigue strength and the fatigue limit. [26][27][28][29][30][31][32][33] It is important to develop efficient, cheaper, and compatible methods to estimate fatigue limit of materials, especially to increase the applicability of these tests for industrial purposes (e.g., component testing).…”

“…[26,27] In recent years, multiple studies are conducted for rapid determination of fatigue limit (or fatigue life) based on temperature evolution of specimens during fatigue testing correlated with fatigue damage of material, which is used to estimate the fatigue strength and the fatigue limit. [26][27][28][29][30][31][32][33] It is important to develop efficient, cheaper, and compatible methods to estimate fatigue limit of materials, especially to increase the applicability of these tests for industrial purposes (e.g., component testing). The load increase test (LIT) is one of these methods being used to estimate fatigue limit of various materials, [31][32][33] which provides reliable estimation of fatigue limit in a timeand cost-efficient manner.…”

Previsão Da Tolerância Às Trincas Curtas Que Nascem De Entalhes

“…Este presente trabalho reporta a metodologia para tolerância do comportamento das trincas curtas baseado nos ensaios para obtenção do limiar de propagação e dos métodos de termografia e extrapolação dos dados N, determinou-se o a0tamanho característico das trincas curtasque é considerado um recurso para impor que todas as trincas, curtas ou não, obedeçam aos limites corretos do trincamento por fadiga.Para a técnica de termografia, sua vantagem consiste na redução dos custos de ensaio de fadiga, seja pela redução dos corpos de prova utilizados e o tempo total do teste em si. Nota-se que o número de ciclos da primeira fase térmica dessa liga de alumínio depende da amplitude da tensão , distinto do observado por Bandeira et al[47][48][49], onde os limites de fadiga SL foram obtidos por testes de incrementos de carga,variando a amplitude de tensão σa a cada ciclo N1. Essa abordagem ainda pode gerar resultados questionáveis porque, para validar esse resultado, é necessário comparar suas estimativas com os SL medidos por métodos mecânicos convencionais, por exemplo, upand-down do Dixon.…”