TY  - MANSCPT
AU  - Ma Quanjin
TI  - Parametric analysis and failure behaviour of spherical-roof contoured-core (SRCC) composite sandwich panel
SN  - THE0009678 (Local)
PY  - 2023///
CY  - Kuantan, Pahang
PB  - UMP
KW  - Faculty of Mechanical and Automotive Engineering Technology
KW  - Dissertations
KW  - Universities and colleges
KW  - Theses
N1  - Faculty of Mechanical and Automotive Engineering Technology; Thesis (Doctor of Philosophy) -- Universiti Malaysia Pahang – 2023; Includes bibliographical references
N2  - Sandwich panels have been increasingly used in weight-critical structural components, which largely stems from the diversity of sandwich core topologies and the variation of the component materials. It is challenging to minimize the weight and manufacturing cost of the composite sandwich structure, which determines the core geometry of the sandwich structure. The 2D periodic core is considered as the traditional core structure with small enclosed space, which provides the certain strength. To improve the mechanical properties, energy-absorbing characteristics, and impact resistance performance of sandwich panels, the 3D periodic core structure is proposed to have the higher strength and impact characteristics with lighter mass. However, the existing or reported 3D periodic cores have certain geometry, restricted space, and complicated preparation process, which mainly lacks of bionic design and consideration of manufacture cost. It is determined that the structural mass, infilled space and fabrication method of 3D periodic core structure mainly affect the mechanical properties of sandwich structure. Therefore, it is an interesting topic to develop the new 3D periodic cores of sandwich panels with an inter-connected network of unit. This study is proposed the novel spherical-roof contoured-core (SRCC) inspired by the core geometry from egg-box and flat-contoured concepts. Moreover, parametric studies and failure behaviour of the SRCC composite sandwich panels were investigated under the quasi-static, low-velocity, and ballistic loadings. SRCC sandwich panels were made from carbon fibre-reinforced plastic (CFRP) with unidirectional and twill patterns and self-reinforced polypropylene (SRPP). The hot compression technique was used to manufacture composite SRCC cores and sandwich panels. Firstly, SRCC composite sandwich panels were carried out the quasi-static test, which investigated the effect of the number of cell units, core wall thickness, foam-filled type, and constraint condition. It was shown that the compressive strength and stiffness increased rapidly with the increasing number of unit cells. It was obtained that with increasing core wall thickness, the compressive stress significantly increased. The initial peak stress was improved 8.86 times for the twill pattern, 6.22 times for the unidirectional pattern, and 4.72 times for SRPP, while the core wall thickness was increased from 0.5 mm to 1.5 mm. Furthermore, the failure behaviour of SRCC sandwich panels was studied under quasi-static loading. Fibre fracture, matrix cracks, delamination, and debonding were observed for CFRP with unidirectional and twill pattern cores. For the SRPP core, buckling, local deformation, and debonding were reported. Secondly, the low-velocity impact test was subsequently conducted on the SRCC composite sandwich panels, which investigated the effect of the core wall thickness, impact position, impact energy, facesheet type, and foam-filled condition. It was found that those parameters significantly affected the impact characteristics of spherical-roof contoured-core sandwich panels. It was observed that fibre/matrix fracture, small-area deamination, and debonding were mainly recognized as the typical failure behaviour of SRCC composite sandwich panels subjected to low-velocity impact. Thirdly, the ballistic test was focused on the failure behaviour and impact resistance characteristics under two impact velocities (194.52 m/s and 234.1 m/s). It was exhibited that the SRCC composite sandwich panels of CFRP with twill pattern provided the maximum impact load and absorbed energy of 0.69 kN and 82.16 J than CFRP with unidirectional pattern and SRPP cores. In addition, the fibre/matrix fracture, delamination, and debonding were mainly observed in the SRCC core and both facesheets of the sandwich structure. To predict the failure behaviour of SRCC composite sandwich panel, finite element modellings were developed to determine the failure behaviour of SRCC panels under quasi-static and dynamic loadings. The user-defined material subroutine (VUMAT) was programmed to simulate the failure behaviour of the SRCC and corresponding sandwich panels following the modified 3D Hashin’s failure criteria. Numerical investigation results were validated with the corresponding experimental investigation results on load versus displacement curves, stress versus strain curves, energy absorption (EA), specific energy absorption (SEA), etc. It was found that the numerical results showed reasonably good agreement with the experimental results, and the failure behaviour of SRCC composite sandwich panels had a good correlation with the corresponding test results. Finally, the experimental results of SRCC composite sandwich panels were compared with the reported data on 2D and 3D periodic core sandwich panels. It is highlighted that the SRCC sandwich structure has great potential for energy absorbers, such as automotive, electric vertical take-off and landing (eVTOL) aircraft under quasi-static and dynamic loadings
ER  -