Ahmed Maslouhi

• Université de Sherbrooke

The main objective of this paper is to study the effect of the key parameters on the mechanical strength of adhesively bonded Al 5052-H36 joints. The key parameters are adhesive type, curing temperatureCuring temperature, and geometrical parameters. To evaluate the effect of these parameters on the performance of bonded joints, single lap joints (S...

This study investigates the fatigue behaviour of overlap laser-welded 1.6 mm thick AA5052-H36 sheets. The oscillation beam laser welding in continuous mode is adopted for preparing defect-free weld seams. Three different stitch-weld orientations (transversal, longitudinal, and diagonal with respect to the load direction, denoted in the present work...

Under dynamic loading conditions, damage in a plain weave Carbon Fiber Reinforced Polymer (CFRP) composite is a complex and multiscale process especially in the presence of a manufacturing flaw. In this context, this paper investigates the impact of an inserted flaw on the damage scenario and stiffness degradation over fatigue life. To achieve this...

Stiffened composite panels have been extensively used thanks to their ability to withstand high load and large deflection. However, their nonlinear behavior and complex damage modes during the post-buckling regime remain challenging and still require research work to improve understanding. In the current study, the buckling and post-buckling respon...

In this study, the laser welding process is used to join 1.6-mm-thick AA5052-H36 sheets in an overlap joint configuration. Both pulse and oscillation laser beam welding were investigated for the first laser pass. Oscillation beam laser welding in continuous-wave mode show more stable and sound weld with no porosity defects compare to pulse wave (PW...

Guided wave propagation and interaction with defects in aerospace structures is addressed in the literature only for specific and limited number of simple components and types of defects. The knowledge-gap based project between industrial and academic researchers presented in this paper aims at providing the industry with an extended knowledge base...

Improving resistance to delamination is still a domain of research interest for researchers and for industrials. In this paper, effects of adding metal particles at interfaces of cross ply fiber-reinforced composite plates are investigated. Composite plates with [0(5)/90(2)/0(5)] configuration graphite fibers and resin epoxy matrix are produced by...

This article presents the development of an experimental methodology based on acoustic emission wave detection for determining delamination onset and propagation in carbon fibre composite materials under quasi-static and fatigue loading. Delamination was investigated in quasi-static interlaminar fracture testing over a wide range of mixed-mode rati...

Damage monitoring, failure prognostics, and remaining service life prediction represent great technological challenges for reliable maintenance of aeronautical structures. Consequently, there is a whole variety of non-destructive evaluation techniques that are available to ensure the quality of the metallic structures. The majority of these techniq...

The main objective of the investigation described in this paper was to develop experimental and modeling methodologies for the characterization of delamination onset in carbon fiber composite materials under quasi-static and fatigue loading. Delamination onset was evaluated by a standard mechanical testing approach and also by using acoustic emissi...

This paper presents the results of an experimental investigation of the effects of long term hygrothermal exposure on mode II delamination propagation in AS4/5276-1, an aerospace grade graphite/epoxy composite. In this study, unidirectional [0]16 composite specimens were conditioned by immersion in water at 70 oC for a ten month period, during whic...

This paper proposes an experimental methodology to monitor the onset of delamination in real time and uses mechanical test methods for measuring interlaminar fracture resistance to determine mixed mode fracture initiation criteria. The main objective is to introduce crack initiation monitoring by acoustic emission (AE) wave detection that can be us...

In this paper, a structural health monitoring strategy for detecting interlaminar delamination in a carbon fiber reinforced polymer structure using Lamb waves is proposed. The delamination is simulated by inserting a Teflon tape between two transverse plies and the Lamb wave generation and measurement is enabled by using piezoceramic elements. The...

Our research works employ preferentially Acousto-Ultrasonic (AU) guided waves to detect the global effects of fatigue loading adhesive joints by analysing the patterns of the guided wave propagation in lap samples. The relationships between ultrasonic wave modes and distinct damaged lap joint model were evaluated by finite difference method algorit...

A Laser-ultrasonic technique has been used as a non-contact evaluation technique to monitor the mechanical property degradation due to the thermal exposure of the materials. Ultrasonic high-energy pulses were generated on a variety of materials, using a Q-switched Nd:YAG laser. The detection of ultrasound waves was performed by a confocal Fabry-Pér...

Laser-Ultrasonic technique has been used as non-contact evaluation technique to monitor the mechanical property degradation due to the thermal exposure of the materials. Ultrasonic high-energy pulses were generated on a variety of materials, using a Q-switched Nd: YAG laser. The detection of ultrasound waves was performed by a confocal Fabry-Pérot...

The global mechanical properties of composite structures in service depend on fiber/matrix interface and interlaminar strength. The paper proposes to use Acoustic Emission (AE) and advanced signal processing to evaluate the interlaminar performance of polymeric composites. A delaminating process simulated with a Double Cantilever Beam (DCB) in open...

The effect of exposure of 7050 aluminum alloy to heat damage has been studied using ultrasonic techniques. Contact, immersion, and laser ultrasonic techniques were used. The relationships of ultrasonic attenuation with static material properties and material microstructure were evaluated. It was shown that attenuation measurements at high frequenci...

This paper describes the use of miniature fiberoptic sensors, embedded within a carbon-epoxy composite material specimen, to measure acoustic emissions emanating from within the material. The response to the acoustic signal is transmitted from the sensor through the optical fibers which can be integrated directly into the material during fabricatio...

Acoustic emission (AE) techniques have been used as a nondestructive method to monitor damage growth in composite laminates. For the purpose of effective identification of failure modes in CFRP, a system which extracts characteristic features of AE waveforms has been developed. Seventeen waveform features or descriptors have been extracted from sig...

Knowledge of the current state of health of a material, particularly advanced composites used for load carrying structure for aircraft or spacecraft, is an ongoing concern throughout the useful life of the hardware. The costs for nondestructive inspection to assess the material condition are large in terms of lost time, equipment required and the d...

The development of quantitative acoustic emission (AE) techniques has made it possible to apply signal processing analyses to recover detailed information from the detected AE signals. This paper focuses on the results of experiments following two different approaches of extracting useful information from AE signals produced in carbon-epoxy composi...

The objective of this work is to study the influence of the moulding conditions of manufacture on the mechanical behaviour of the composites, when which they are submitted to mechanical loading. In order to evaluate the quality of interfacial adhesion, two non-destructive testing procedures were combined. Laser ultrasonic was employed to evaluate t...

yes