Browsing by Author "Xu, Xiaodong"

Now showing 1 - 5 of 5
  • Thumbnail Image
    ItemOpen Access
    Hygrothermal effects on translaminar fracture toughness of quasi-isotropic laminates with different stacking sequences
    (Elsevier, 2023-12-14) Gong, Bowen; Ge, Yuzhong; Wang, Huan; Peng, Hua-Xin; Wisnom, Michael R.; Xu, Xiaodong
    Hygrothermal effects on the translaminar fracture toughness of the carbon/epoxy composite with two different stacking sequences at 120 °C were studied and the failure mechanisms are explained. The eccentrically loaded single-edge-notch tension (ESET) experiments showed that two different quasi-isotropic stacking sequences ([90/45/0/-45]4s and [45/90/-45/0]4s) have negligible difference in translaminar fracture toughness. It was found that the fracture toughness of conditioned specimens at hot temperature wet (HTW) condition increased by 75 % compared to that at room temperature dry (RTD). The average saturated damage height at HTW increased by 48 % compared with that at RTD according to ex situ X-ray computed tomography (CT) observation. The larger saturated damage height observed in the 0° plies of the HTW specimens results in the higher translaminar fracture toughness.
  • Thumbnail Image
    ItemOpen Access
    An innovative tactile sensor roller for composites inspection
    (IEEE, 2024-06-05) Lu, Zhenyu; Li, Xiaolong; Li, Tunwu; Xu, Xiaodong; Yang, Chenguang
    A vision-based tactile sensor roller prototype has been designed and developed to detect defects on composite prepreg and dry fabric surfaces. The tactile sensor features an innovative design comprising a transparent acrylic tube encased in a gel elastomer. The outer tube serves as a protective and flexible layer, while the inner structure includes a connecting shaft equipped with a camera, force, and speed sensors. This configuration allows for detailed capture of tactile information, integrating visual and pressure data for comprehensive sensory feedback. The connecting shafts are fitted with wheels and handles at both ends, enabling human manipulation and control. Typical defects such as wrinkles, gaps, overlaps and foreign objects and debris (FOD) can be detected by this prototype. In this study, we assessed the performance of the tactile sensor roller by rolling it across areas affected by human-made composite prepreg and dry fabric defects that include wrinkles and foreign objects. With the comparison of the tactile image results, we have demonstrated that the tactile sensor roller can identify flaws with a precision of 0.125mm. It can efficiently examine a 35cm by 18cm section of woven fabric without compromising the integrity of the 3D data gathered. This innovative tactile sensor is set to enhance the automation of the hand layup process. It enables real-time quality control, substantially reducing the need for extensive manual inspections. This leads to a significant cut in inspection costs, making the manufacturing process both more efficient and cost-effective.
  • Thumbnail Image
    ItemOpen Access
    Observation of damage initiation for trans-laminar fracture using in situ fast synchrotron x-ray radiography and ex situ x-ray computed tomography
    (Springer, 2024-02-21) Xu, Xiaodong; Leung, Nathanael; Jargalsaikhan, Urangua; Bongaers, Evi; Sui, Tan
    Trans-laminar fracture is an important topic for engineering composites. In this study, trans-laminar fracture initiation in quasi-isotropic carbon/epoxy laminates made of non-crimp fabrics was examined using in situ fast synchrotron X-ray radiography and ex situ X-ray computed tomography. The maximum split lengths were measured by in situ radiography and were compared with the predicted values in a detailed FE model using cohesive elements. Ex situ computed tomography scans were also conducted to confirm that no fibre breakage occurs before the final load drop in the experiments. In situ and ex situ observations are complementary for the understanding of damage initiation.
  • Thumbnail Image
    ItemOpen Access
    A stochastic modelling framework for predicting flexural properties of ultra-thin randomly oriented strands
    (Taylor and Francis, 2024-05-09) Xu, Xiaodong; Jesus, André; Wan, Yi; Takahashi, Jun
    A stochastic modelling framework is developed to predict the flexural properties of high-strength sheet moulding compounds made of randomly oriented ultra-thin carbon fibre-reinforced thermoplastic prepreg tapes. The model enables reliable designs using ultra-thin randomly oriented strands with less testing, leading to potential applications in automotive primary structures. The stochastic model is based on a Monte Carlo simulation. The flexural modulus is predicted using classical laminate theory, while the flexural strength is predicted by following a Weibull distribution. Fibre discontinuities are considered through stress concentrations introduced by tape overlaps. The results are validated against new 3-point bending and previously reported 4-point bending experimental results. A scaling effect on strength and scatter is predicted, and its implications for structural applications are also discussed.
  • Thumbnail Image
    ItemOpen Access
    Towards a virtual test framework to predict residual compressive strength after lightning strikes
    (Elsevier, 2023-08-06) Millen, Scott L. J.; Xu, Xiaodong; Mukhopadhyay, Supratik; Wisnom, M. R.; Murphy, A.
    A novel integrated modelling framework is proposed as a set of coupled virtual tests to predict the residual compressive strength of carbon/epoxy composites after a lightning strike. Sequentially-coupled thermal-electric and thermo-mechanical models were combined with Compression After Lightning Strike (CAL) analyses, considering both thermal and mechanical lightning strike damage. The predicted lightning damage was validated using experimental images and X-ray Computed Tomography. Delamination and ply degradation information were mapped to a compression model, with a maximum stress criterion, using python scripts. Experimental data, in which artificial lightning strike and compression testing were performed, was used to assess the predictive capabilities of the framework, considering three lightning strike peak current amplitudes (25, 50, and 75 kA). The framework herein achieved a residual strength prediction within 6% of the experimental values for all peak currents. The relationship between individual lightning damage morphologies (thermal, mechanical and delamination damage) and CAL strength has been numerically established.