Delamination is a type of representative damage in composite structures, severely degrading structural integrity and reliability. The identification of delamination is commonly treated as an issue of nondestructive testing. Differing from existing studies, a hybrid optimization algorithm HOA , combining particle swarm optimization PSO with simplex method SM , is proposed to identify delaminatio...

Fiber reinforced polymeric composites can be employed for the construction of structures that are highly durable and easy to fabricate. At EMPA, a prototype footbridge with girders and deck made of pultruded composite sections has been designed and constructed. For thin-wall pultruded sections such as I-beam or T-beam, delaminations can form easily at the web/flange junction. If the delaminatio...

Electrical Impedance Tomography (EIT) as an imaging technique producing a 2D or 3D impedance image (conductivity or impedivity) of the subject under test. It can be used for delamination detection and evaluating the damage location, size, strain and severity for Structure Health Monitoring (SHM) of aerospace composites i.e. Carbon-fibrereinforced polymer (CFRP) composites. Keywords—Electrical I...

In this paper, a distant acoustic-laser NDE technique is proposed, utilizing a high powered standoff parametric acoustic array (PAA) and laser Doppler vibrometry (LDV), for the detection of debonding and delamination in multi-layer composite systems. Fiber-reinforced polymer wrapped concrete cylinder specimens with artificial defect were manufactured and used in the validation of the technique....

Nowadays, due to high ratio of strength to weight, composite cylindrical shells are extensively used in a great variety of different industrial applications and under different cases of loads. In this study, the buckling of composite cylindrical shells was examined under uniform external pressure. The buckling analysis of composite cylindrical shells was first done by using theoretical relation...

This paper presents a method for detecting multiple delaminations in composite laminates using non-contact phased arrays. The phased arrays are implemented with a non-contact scanning laser Doppler vibrometer (SLDV). The array imaging algorithm is performed in the frequency domain where both the guided wave dispersion effect and direction dependent wave properties are considered. By using the n...

In this work, the ultrasonic signals are modelled as a superposition of many Gaussian echoes with unknown parameters. The detection of ultrasonic echoes using Maximum A Posteriori estimation principle, based on the prior knowledge of the spectral characteristic of the ultrasonic transducer, has been used in order to estimate the unknown parameters. A simulation study validated by experimentatio...

The deteriorating national infrastructures demand improved non-destructive evaluation (NDE) methods for detection of defects which reduce the integrity of the structures. Vibration resonance tests offer an efficient NDE method to identify and characterize shallow (near surface) delamination defects in reinforced concrete slabs In this study, we compare the capability to visualize near surface d...

Nowadays, due to high ratio of strength to weight, composite cylindrical shells are extensively used in a great variety of different industrial applications and under different cases of loads. In this study, the buckling of composite cylindrical shells was examined under uniform external pressure. The buckling analysis of composite cylindrical shells was first done by using theoretical relation...

Blistering, delamination, substrate deterioration Blistering, delamination, corrosion Blistering, reduced cohesion, film splitting, delamination Blistering, reduced cohesion, delamination, corrosion Blistering, intercoat delamination From components of paint film (e.g., inhibitive pigments, solvents, additives, etc.) From components of lower paint films (e.g., inhibitive pigments, solvents, add...