Towards a faster determination of high cycle fatigue properties taking into account the influence of a plastic pre-strain from selfheating measurements

AbstractThe high cycle fatigue (HCF) is a major element for a great design of automotive parts. A wide part of the steel sheets for the automotive industry are stamped, sometimes deeply. During this operation, the steel is plastically strained in different directions, so that a good prediction of the fatigue behaviour requires the determination of the fatigue properties of the pre-strained material. Nowadays, the evolution of HCF properties is often neglected. There are two major reasons for this lack. On the one hand, a good finite element simulation of the forming operation to predict pre-strain field is still a difficult task. On the other hand the time dedicated to traditional fatigue test campaigns (e.g. staircase method) to quantitatively identify this influence is prohibitive. To determine faster this influence, it is proposed to use self heating measurements under cyclic loadings. To illustrate this approach, different pre-strain paths are studied: shear and tension. Finally, a model taking into account the influence of pre-strain on high cycle fatigue properties is proposed and identified from self-heating measurements. The validation of the proposed approach is obtained by predicting S/N curves for pre-strain to 20% of a dual phase steel

Digital image correlation and infrared measurements to determine the influence of a uniaxial pre-strain on fatigue properties of a dual phase steel.

The high cycle fatigue (HCF) is a major element for a great design of automotive parts. A wide part of the steel sheets for the automotive industry are stamped, sometimes deeply. During this operation, the steel is plastically strained in different directions, so that a good prediction of the fatigue behavior requires the determination of the fatigue properties of the pre-strained material. Nowadays, the evolution of HCF properties is often neglected, because of prohibitive time dedicated to traditional fatigue campaigns. To reduce the characterization time, self-heating measurements are used. This approach permits to identify the influence of homogeneous pre-strain on fatigue properties. The aim of this paper is to develop an original experimental test to identify this influence for a wide range of pre-strain with only one specimen. The study of a particular case of specimen with a constant gradient of pre-strain is presented. Digital image correlation is a way to determine the heterogeneity of the plastic pre-strain on the specimen and infrared measurements with a ”1D” approach allows the determination of the influence of a plastic pre-strain on the fatigue properties of the studied steel

Influence of Surface Integrity and Coating on the High Cycle Fatigue Properties of 300M Steel from Self-Heating Tests under Cyclic Loads

International audienc

An energetic criterion for the fatigue of rubbers: an approach based on a heat build-up protocol and μ-tomography measurements

International audienc