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Full-Text Articles in Mechanical Engineering
Influence Of Stitch Density And Stitch Thread Thickness On Compression After Impact Strength Of Stitched Composites, Kwek Tan, N. Watanabe, Y. Iwahori, T. Ishikawa
Influence Of Stitch Density And Stitch Thread Thickness On Compression After Impact Strength Of Stitched Composites, Kwek Tan, N. Watanabe, Y. Iwahori, T. Ishikawa
Dr. Kwek-Tze Tan
This study aims to investigate the influence of stitch density and stitch thread thickness on compression after impact (CAI) strength of stitched composites. Unstitched laminated composites and specimens stitched with varying stitch density and stitch thread thickness are subjected to impact damage and then compressive loading. It is shown that stitched composites have higher CAI strength than unstitched counterpart due to smaller impact-induced delamination area, where local buckling occurs during compressive failure. However, it is revealed that the effectiveness of stitching in suppressing delamination growth and inhibiting sublaminate buckling under compressive loading is intimately related to stitch density. It is …
Validation Of Delamination Reduction Trend For Stitched Composites Using Quasi-Static Indentation Test, Kwek Tze Tan, N. Watanabe, A. Yoshimura, Y. Iwahori
Validation Of Delamination Reduction Trend For Stitched Composites Using Quasi-Static Indentation Test, Kwek Tze Tan, N. Watanabe, A. Yoshimura, Y. Iwahori
Dr. Kwek-Tze Tan
A novel empirical-based Delamination Reduction Trend (DRT) for stitched composites has been recently proposed. The DRT is capable of predicting the effective reduction in impact induced delamination area due to the influence of stitching. DRT simply relates two parameters: normalized delamination area and stitch fibre volume fraction, to characterize the effectiveness of stitching in impact damage suppression. This paper seeks to validate the DRT by using quasi-static indentation (QSI) test, which is considered analogous to low velocity impact test, due to similar structural response. Results from QSI test show good agreement with DRT. Furthermore, limitations in DRT have been established.
Experimental Investigation Of Bridging Law For Single Stitch Fibre Using Interlaminar Tension Test, Kwek Tan, N. Watanabe, Y. Iwahori
Experimental Investigation Of Bridging Law For Single Stitch Fibre Using Interlaminar Tension Test, Kwek Tan, N. Watanabe, Y. Iwahori
Dr. Kwek-Tze Tan
In this study, a novel Interlaminar tension test (ITT) method was performed to experimentally investigate the bridging and fracture process of a single stitch fibre used to improve the delamination strength of composite laminates. Kevlar-29, of various thread thicknesses (44, 66, 88 and 132 tex), was used as the through-thickness stitch fibre in the ITT experiments. Key empirical force and displacement parameters, which governed the stitch fibre bridging law, were characterised and identified. Relationships of such parameters with thread thicknesses were determined. Fibre fracture load and fibre fracture energy are found to increase with increasing thread thickness. Frictional pull-out force …
Stitch Fiber Comparison For Improvement Of Interlaminar Fracture Toughness In Stitched Composites, Kwek Tan, N. Watanabe, Y. Iwahori
Stitch Fiber Comparison For Improvement Of Interlaminar Fracture Toughness In Stitched Composites, Kwek Tan, N. Watanabe, Y. Iwahori
Dr. Kwek-Tze Tan
In this study, strain energy release rates are measured and compared for laminated composites reinforced by through-thickness stitching using different stitch fiber materials — Carbon, Kevlar, and Vectran. Strain energy release rates are evaluated experimentally using the DCB test and validated computationally using FEA. The FE model of the stitched composite incorporates a novel four-step stitch fracture process, namely: interfacial debonding, slack absorption, fiber breakage, and pull-out friction. The FE predictions of GIC show good agreement with the experimental results. It is revealed that the relationship between G IC and stitch density, or stitch thread volume fraction for all …
Interlaminar Fracture Toughness Of Vectran-Stitched Composites - Experimental And Computational Analysis, Kwek Tan, N. Watanabe, M. Sano, Y. Iwahori
Interlaminar Fracture Toughness Of Vectran-Stitched Composites - Experimental And Computational Analysis, Kwek Tan, N. Watanabe, M. Sano, Y. Iwahori
Dr. Kwek-Tze Tan
In this article, mode I interlaminar fracture toughness (GIC) of Vectran-stitched laminated composite is determined experimentally and computa- tionally. Critical strain energy release rates are measured by performing double can- tilever beam test on composites stitched with Vectran as stitch fiber, and are found to increase with increasing stitch thread thickness and stitch density. It is also revealed that the relationship between GIC and stitch density or stitch thread volume fraction appears to be linear. Interlaminar tension test is conducted to identify important fracture behavior of a single Vectran stitch fiber thread. The finite-element (FE) model of the stitched composite …
Effect Of Stitch Density And Stitch Thread Thickness On Damage Progression And Failure Characteristics Of Stitched Composites Under Out-Of-Plane Loading, Kwek Tan, A. Yoshimura, N. Watanabe, Y. Iwahori, T. Ishikawa
Effect Of Stitch Density And Stitch Thread Thickness On Damage Progression And Failure Characteristics Of Stitched Composites Under Out-Of-Plane Loading, Kwek Tan, A. Yoshimura, N. Watanabe, Y. Iwahori, T. Ishikawa
Dr. Kwek-Tze Tan
In this paper, the damage progression and failure characteristics of stitched composites under out-of-plane loading are experimentally investigated. Test specimens, stitched with various stitch densities and stitch thread thicknesses, are studied using quasi-static indentation test. Test specimens are loaded and unloaded in 0.5 mm incremental indentation displacement to examine for damage phenomena using non-destructive inspection techniques namely ultrasonic C-scan, X-ray radiography and X-ray micro-computed tomography to elucidate complex damage mechanisms and fracture behavior. Recorded test history of load–displacement curves indicate that damage progression can be characterized into three stages: damage initiation, damage propagation and final damage failure. Results show that …
Effect Of Stitch Density And Stitch Thread Thickness On Compression After Impact Strength And Response Of Stitched Composites, Kwek Tan, N. Watanabe, Y. Iwahori, T. Ishikawa
Effect Of Stitch Density And Stitch Thread Thickness On Compression After Impact Strength And Response Of Stitched Composites, Kwek Tan, N. Watanabe, Y. Iwahori, T. Ishikawa
Dr. Kwek-Tze Tan
In this paper, the damage failure and behaviour of stitched composites under compression after impact (CAI) loading are experimentally investigated. This study focuses on the effect of stitch density and stitch thread thickness on the CAI strength and response of laminated composites reinforced by through-thickness stitching. Experimental findings show that stitched composites have higher CAI failure load and displacement, which corresponds to higher energy absorption during CAI damage, mainly attributed to greater energy consumption by stitch fibre rupture. The coupling relationships between CAI strength, impact energy, stitch density and stitch thread thickness are also revealed. It is understood that the …
Impact Damage Resistance, Response, And Mechanisms Of Laminated Composites Reinforced By Through-Thickness Stitching, Kwek Tan, N. Watanabe, Y. Iwahori
Impact Damage Resistance, Response, And Mechanisms Of Laminated Composites Reinforced By Through-Thickness Stitching, Kwek Tan, N. Watanabe, Y. Iwahori
Dr. Kwek-Tze Tan
In this article, the study of impact damage of laminated composites reinforced by through-thickness stitching is investigated and presented in threefold. Specimens stitched with varying stitch density and stitch thread thickness are subjected to low-velocity impact via a drop-weight machine. Impact damage resistance is first studied by examining the extent of delamination area in damaged specimens using ultrasonic C-scan analysis. It is revealed that higher stitch density is more capable of impeding delamination growth by arresting cracks at closer interval and suppressing crack propagation. The use of thicker stitch thread offers slight improvement to damage resistance by marginal reduction in …