3D TEXTILE PREFORMS AND COMPOSITES FOR AIRCRAFT STRCUTURES: A REVIEW

Over the last decades, the development of 3D textile composites has been driven the structures developed to overcome disadvantages of 2D laminates such as the needs of reducing fabrication cost, increasing through-thickness mechanical properties, and improving impact damage tolerance. 3D woven, stitched, knitted and braided preforms have been used as composites reinforcement for these types of composites. In this paper, advantages and disadvantages of each of them have been comprehensively discussed. The fabric architects and their specification in particular stitched preforms and their deformation mode for aerospace applications have been reviewed. Exact insight into various types of damage in textile preforms and composite that have the potential to adversely affect the performance of composite structure along with their inspection using NDT techniques have been elaborated. The research review reported in this paper can be very valuable to researchers to release the 3D composite behaviour under different loading conditions and also to get familiar with the manufacture of high quality textile composite for aircraft structures

Damage characterization of aircraft fuselage using vibrothermography technique-review and analysis

Vibrothermogrphy is a promising non-destructive technique that uses ultrasonic elastic waves to detect damages and is typically applied in the aerospace and automotive industries. This technique allows for defect selective imaging using thermal waves that are generated by ultrasound waves. In this paper, vibrothermography technique was applied to the aircraft fuselage to detect its damage. The influence of the damage on the temperature distribution at the damage region on the aluminum was investigated by finite element technique. Comprehensive understanding in edge crack in fuselage heating caused by local friction between crack surfaces was obtained

Integrity assessment of preforms and thick textile reinforced composites for aerospace applications

Three-dimensional (3D) textile composites containing in-plane fibers and fibers oriented in the thickness direction offer some advantages over two-dimensional (2D) textile composites. These advantages include high delamination resistance and improved damage tolerance. Textile composites containing 3D textile preforms have mostly been developed by the aerospace industry for structural applications such as wing panels, landing gear, rocket nozzles, and the Orion capsule, and so forth. This thesis is devoted to structural integrity assessment of textile composites including 2D and 3D tufted composites by combining destructive and non-destructive techniques. In the first part of the thesis, non-destructive techniques including X-ray computed tomography (CT) and ultrasound-based techniques (UT) were used to detect two significant processinduced defects called fiber breakage and fabric misalignment. The second part focuses on studying of the influence of manufacturing defects introduced during the tufting process on the mechanical properties. Experimental results proved that X-ray CT facilitates the characterization of those two manufacturing defects as well as the architecture of the textile fabrics. Furthermore, mesoscale modeling of a 2D woven composite was successfully performed for the analysis of the fiber breakage defect influence and fiber architecture on wave propagation. Experimental results prove that tufting the preform assists in locking and restricting the yarn's movement in the preform. The threads used for tufting have a major influence on tensile strength, as stronger threads may give higher resistance. Tufting increases the compaction force due locking of fiber bundles, therefore, a higher compaction force is needed to obtain a fiber volume of up to 50 percent in comparison to an untufted preform. The drape behaviour of a tufted preform is influenced by tufting so that high drapability is observed for a tufted preform along with local variation of fiber bundle occurred around tufting reinforcements. The variation of preform geometry was achieved by laser scanning. Furthermore, the CT capability was investigated as a means for recognizing the shapes and locations of voids in composites. Tufted composites with transverse tufting suffer less reduction in the tensile strength than those with longitudinal tufting. Tufted composites are found to have lower fatigue life ithan untufted composites, while an improved compressive strength and tensile strength at high strain rate are observed. Tufting improves the mechanical properties of tufted honeycomb composites under local compression and bending loadings. Mostly, the damage initiates from resin-rich regions around the tufting reinforcements. The acceptance of 3D tufted composites for use in primary aerospace structures is highly dependent on the accuracy and reliability of experimental data to recognize the degree to which tufting reinforcements improve or degrade the mechanical properties. In this thesis, the correlation between the tufted preforms and composite properties and the changes to mechanical properties is discussed for a specific tufting configuration. Experimental data are reported on both the low-rate and high-rate static and fatigue strengths at various stress levels. Microstructural examination is carried out by using the high resolution microscopy and CT techniques. The results of this thesis contribute to the investigation of the integrity and damage tolerance in 3D tufted composites toward certifying purposes for future transport aircraft. Since the certification of tufted composites for aerospace applications is still problematic due to the lack of dependable non-destructive evaluation techniques for their inspection and those manufacturing factors can considerably influence their performance, this is an important problem to tackle in the field of aerospace composite engineering