Relaxação de tensões em metais

AUTOR(ES)

Thereza Christina Robalinho Penna

DATA DE PUBLICAÇÃO

1981

RESUMO

Any metal or alloy which is submitted to a stress level, corresponding to a given strain, will gradually relax if this strain is maintained constant. This effect which is named Stress Relaxation offers means to investigate the dislocation dynamics of metals. One objective of the present investigation was to study the machine s contribution on the stress relaxation tests by using a servohydraulic system with either strain or stroke control mode. Several equations relating stress rate and stress are applied to the experimental analysis, which were conducted at room temperature, on Cu and zinc specimens. By means of these equations we have studied the parameter b relating stress and strain rate, in order to verify if the dislocation structure remains constant in the relaxation tests. The parameters obtained by Li?s analysis were also studied. We have questioned the internal stress obtained in this way, even if we have an apparent good agreement of the experimental results with the application of Li?s method. Stress relaxation experiments were used to obtain experimental data to study the concept of plastic equation of state and to show that the conclusions made by some authors may be questioned when recovery occurs

ASSUNTO(S)

tensões residuais resistencia de materiais metais - fadiga

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