Open Access. Powered by Scholars. Published by Universities.®
- Discipline
- Keyword
-
- Mechanical Engineering (12)
- Stitched composites (8)
- Delamination (6)
- Damage tolerance (3)
- Impact behavior (3)
-
- Stitching (3)
- Kevlar (2)
- Quasi-static indentation (2)
- Stitch fiber (2)
- Vectran (2)
- B. Delamination (1)
- B. Fracture (1)
- Blast-wave (1)
- Bridging law (1)
- C. Fiber bridging (1)
- Carbon (1)
- Compression after impact (1)
- D. Non-destructive testing (1)
- Damage mechanisms (1)
- Damage progression (1)
- Elastic metamaterials (1)
- Fibre bridging (1)
- Impact (1)
- Impact behaviour (1)
- Impact damage (1)
- Impact damage resistance (1)
- Impact damage response (1)
- Interlaminar fracture toughness (1)
- Interlaminar tension test (1)
- Interlaminar toughness (1)
- File Type
Articles 1 - 19 of 19
Full-Text Articles in Mechanical Engineering
Metacomposites Protection System Against Primary Blast Injury, Kwek Tan, C. Sun
Metacomposites Protection System Against Primary Blast Injury, Kwek Tan, C. Sun
Dr. Kwek-Tze Tan
There is an increasing use of improvised explosive devices (IEDs) in terrorist and insurgent activities. Exposure to blast is becoming more frequent. Blast related injuries can be inflicted at various levels. Primary blast injury results from blast wave-induced changes in atmospheric pressure, causing organs and tissues to rupture due to shearing and stretching at different rates. Secondary blast injury results from objects put in motion by the blast wind impacting a person. Tertiary blast injury results from a person being blown into solid objects by the blast wind. This paper deals with the protection system against primary blast injury by …
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.
Active Infrared Sensing Of Impact Damage In Carbon Fibre Reinforced Polymer, Kwek Tze Tan, Liping Zhao, Shaochun Ye, Tong Kuan Chuah, Pramoda Kumari Pallathadka, Hui Ru Tan
Active Infrared Sensing Of Impact Damage In Carbon Fibre Reinforced Polymer, Kwek Tze Tan, Liping Zhao, Shaochun Ye, Tong Kuan Chuah, Pramoda Kumari Pallathadka, Hui Ru Tan
Dr. Kwek-Tze Tan
With the growing demand of carbon fibre reinforced plastic (CFRP) in aerospace, marine and automobile industries, much attention is devoted to characterizing the material strength and characteristics of failure. This paper demonstrated the feasibility to estimate the internal damage non-destructively as a result of a quantified impact applied on 16-ply fabric CFRP. On thermography images at different heating time, differences were observed between intact area and area with internal damage. The estimation of 1D extent of damage using thermographic analysis was compared with images observed with cross sectional microscopic. The results suggest that qualitative analysis using thermography shows potential to …
Impact-Induced Delamination Suppression In Laminated Composites Using Through-Thickness Stitching, Kwek Tan, N. Watanabe, H. Hoshi, Y. Iwahori
Impact-Induced Delamination Suppression In Laminated Composites Using Through-Thickness Stitching, Kwek Tan, N. Watanabe, H. Hoshi, Y. Iwahori
Dr. Kwek-Tze Tan
This paper aims to investigate the effectiveness of using through-thickness stitching in suppressing impact-induced delamination growth in laminated composites. Low-velocity impact tests are conducted on unstitched and stitched specimens with varying stitch density and stitch thread thickness. Results show that stitching effectively bridges and arrests delamination crack, and reduces delamination growth up to 40%. It is also revealed that increasing stitch density is more effective (23% reduction) in minimising delamination area than increasing stitch thread thickness (8% reduction). A novel empirical-based Delamination Reduction Law (DRL) has been formulated to predict the delamination reduction in stitched composites due to impact loading. …
Negative Effective Mass Density Of Acoustic Metamaterial Using Dual-Resonator Spring-Mass Model, Kwek Tze Tan, H. H. Huang, C. T. Sun
Negative Effective Mass Density Of Acoustic Metamaterial Using Dual-Resonator Spring-Mass Model, Kwek Tze Tan, H. H. Huang, C. T. Sun
Dr. Kwek-Tze Tan
In this paper, we propose an acoustic metamaterial with a microstructure consisting of two internal resonators. The performance of this dual-resonator metamaterial is compared to the original singleresonator metamaterial. Analytical findings show that the dual-resonator metamaterial exhibits its negative effective mass density over a larger frequency spectrum, particularly at two distinctively asymptotic regions. The wave propagation phenomenon in the metamaterial is investigated using finite element simulation. Computational results reveal that the dual-resonator metamaterial is capable of attenuating wave propagation in a larger operating frequency. Practical applications like vibration control and blast mitigation are demonstrated and discussed.
Progressive Damage In Stitched Composites Under Impact Loading, Kwek Tze Tan, N. Watanabe, A. Yoshimura, Y. Iwahori, T. Ishikawa
Progressive Damage In Stitched Composites Under Impact Loading, Kwek Tze Tan, N. Watanabe, A. Yoshimura, Y. Iwahori, T. Ishikawa
Dr. Kwek-Tze Tan
Damage in carbon fibre reinforced plastics (CFRP) due to impact loading is an extremely complex phenomenon that comprises of multiple failure mechanisms like intra-laminar matrix cracks, interlaminar delamination, fibre pull-out and fibre fracture. In stitched composites, impact damage behavior is further complicated by the presence of through-thickness stitching [1, 2], which not only favorably increases mode I/II interlaminar strength [3, 4], but also inevitably creates geometrical defects like weak resin-rich pockets around stitch threads and misalignment of in-plane fibres. Computational modeling has been used to simulate progressive damage effectively [5]. However, the complexity of impact damage progression in stitched composites …
Interactive Behavior Of Internal Resonators In Acoustic Metamaterials Under Impact Pulse Loading, Kwek Tan, C. Sun
Interactive Behavior Of Internal Resonators In Acoustic Metamaterials Under Impact Pulse Loading, Kwek Tan, C. Sun
Dr. Kwek-Tze Tan
No abstract provided.
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 …
Understanding Effectiveness Of Stitching In Suppression Of Impact Damage: An Empirical Delamination Reduction Trend For Stitched Composites, Kwek Tan, N. Watanabe, Y. Iwahori, T. Ishikawa
Understanding Effectiveness Of Stitching In Suppression Of Impact Damage: An Empirical Delamination Reduction Trend For Stitched Composites, Kwek Tan, N. Watanabe, Y. Iwahori, T. Ishikawa
Dr. Kwek-Tze Tan
In this paper, a novel empirical trend has been identified to understand the delamination reduction in stitched composites subjected to impact loading. This empirical-based Delamination Reduction Trend (DRT) is developed based on an extensive series of low-velocity impact tests using specimens of different laminate thicknesses, stitch densities and stitch thread linear (mass) densities, subjected over a range of impact energy levels. The DRT simply relates two parameters: normalized delamination area (DelamNorm) and stitch fiber volume fraction (Vft), to characterize the effectiveness of stitching in impact damage suppression. DRT evidently shows a bi-linear behavior: first, …
X-Ray Radiography And Micro-Computed Tomography Examination Of Damage Characteristics In Stitched Composites Subjected To Impact Loading, Kwek Tan, N. Watanabe, Y. Iwahori
X-Ray Radiography And Micro-Computed Tomography Examination Of Damage Characteristics In Stitched Composites Subjected To Impact Loading, Kwek Tan, N. Watanabe, Y. Iwahori
Dr. Kwek-Tze Tan
In this study, X-ray radiography and X-ray micro-computed tomography (μCT) are employed to characterise impact damage in stitched composites, paying particular attention to the influence of stitch density and stitch thread thickness. Laminated composites, stitched with varying stitch densities and stitch thread thicknesses, are subjected to low-velocity impact loading at various energy levels. X-ray radiography is used to observe in-plane matrix cracks and overall delamination propagation; whilst μCT is exploited to examine cross-sectional views showing detailed through-thickness matrix cracks distribution and 3D delamination damage pattern. It is revealed that stitches act as crack initiation sites, due to the presence of …
Optimizing The Band Gap Of Effective Mass Negativity In Acoustic Metamaterials, Kwek Tan, H. Huang, C. Sun
Optimizing The Band Gap Of Effective Mass Negativity In Acoustic Metamaterials, Kwek Tan, H. Huang, C. Sun
Dr. Kwek-Tze Tan
A dual-resonator microstructure design is proposed for acoustic metamaterials to achieve broadband effective mass negativity. We demonstrate the advantage of acoustic wave attenuation over a wider frequency spectrum as compared to the narrow band gap of a single-resonator design. We explicitly confirm the effect of negative effective mass density by analysis of wave propagation using finite element simulations. Examples of practical application like vibration isolation and blast wave mitigation are presented and discussed.
Effect Of Stitch Density And Stitch Thread Thickness On Low-Velocity Impact Damage Of Stitched Composites, Kwek Tan, N. Watanabe, Y. Iwahori
Effect Of Stitch Density And Stitch Thread Thickness On Low-Velocity Impact Damage Of Stitched Composites, Kwek Tan, N. Watanabe, Y. Iwahori
Dr. Kwek-Tze Tan
Effect of stitch density and stitch thread thickness on low-velocity impact damage of stitched composites is investigated experimentally. Physical examination on damage surfaces shows that stitches perform as crack initiators, as well as crack arrestors. Longer matrix cracks are observed in densely-stitched composites, in contrast to isolated matrix cracks found in moderately-stitched composites. Ultrasonic C-scan evidently compares the delamination areas and concludes that specimens with higher stitch density and thread thickness are more capable of impeding delamination growth by effectively bridging delamination cracks. Load–time curves reveal that the onset of delamination is not influenced by stitch density and thread thickness. …
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 …
Blast-Wave Impact Mitigation Using Negative Effective Mass Density Concept Of Elastic Metamaterials, Kwek Tan, H. Huang, C. Sun
Blast-Wave Impact Mitigation Using Negative Effective Mass Density Concept Of Elastic Metamaterials, Kwek Tan, H. Huang, C. Sun
Dr. Kwek-Tze Tan
This paper presents the use of elastic metamaterials for impact attenuation and blast-wave mitigation. Metamaterials represent a novel and emerging research area where materials exhibit exceptional properties not commonly found in natural materials. These unique properties are enacted by specifically designed microstructures. In this study, a single-resonator model and a dual-resonator microstructural design are proposed to exhibit negative effective mass density. The effect of negative effective mass density is explicitly confirmed by analysis of wave propagation using numerical simulations. Results evidently show that impact stress wave attenuation occurs over a wider frequency spectrum for the dual-resonator model as compared to …
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 …