Estimation of Notched Composite Plates Fatigue Life Using Residual Strength Model Calibrated by Step-Wise Tests

Area of Science:

• Materials Science
• Mechanical Engineering
• Composite Materials

Background:

• Fatigue life prediction in composite materials is crucial for structural integrity.
• Traditional methods often require extensive testing and numerous samples.
• Notched composite structures present unique challenges due to stress concentrations.

Purpose of the Study:

• To introduce and validate a novel fatigue life prediction technique for notched composite plates.
• To develop a residual strength model calibrated using step-wise fatigue tests.
• To assess the efficiency of step-wise testing in model calibration.

Main Methods:

• Development of a residual strength-based fatigue model.
• Calibration of the model using step-wise fatigue tests.
• Experimental investigation using glass/epoxy composite plates with circular and elliptical cut-outs.
• Analysis of loading parameters: testing frequency, stress ratio, maximal fatigue stress, and cut-out geometry.

Main Results:

• The step-wise fatigue test approach enables model calibration with fewer samples.
• The fatigue model effectively incorporates key loading parameters and geometry.
• Predicted fatigue life showed good agreement with experimental durability data.
• Damage growth rate and fatigue life were analyzed under various loading conditions.

Conclusions:

• The proposed residual strength model calibrated via step-wise fatigue tests is effective for predicting fatigue life in notched composite plates.
• Step-wise testing offers a more sample-efficient calibration method.
• The model's accuracy is validated by experimental results, confirming its applicability.