Article
Engineering, Aerospace
Noah Ledford, Mathieu Imbert, Michael May
Summary: The high-rate in-plane shear properties of IM7/8552 carbon/epoxy composite material were investigated, showing an increase in in-plane shear strength with increasing loading rate. The data confirmed the in-plane shear strengths measured at different strain rates. Leveraging a Johnson-Cook-type semilogarithmic scaling law, the study provides a method to describe the evolution of in-plane shear strength with increasing loading rate.
Article
Engineering, Mechanical
Alan T. Nettles, Baxter W. Barnes, William E. Guin, James P. Mavo
Summary: This study conducted compression after impact (CAI) strength testing on foam core sandwich structures with carbon/epoxy face sheets using both blunt and sharp tip impactors at three different energy levels. The results showed that the transverse displacement, maximum load of impact, BVID threshold energy, and absorbed energy of impact differed between the blunt and sharp impactors. The CAI strength values also varied depending on the impact energy level and the type of impactor used.
JOURNAL OF SANDWICH STRUCTURES & MATERIALS
(2023)
Article
Engineering, Mechanical
John-Alan Pascoe
Summary: The slow-growth certification approach has the potential to reduce weight in composite aircraft structures, but current methods lack accuracy in predicting damage growth and final failure, mainly due to knowledge gaps in damage characterization, prediction, and final failure.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2021)
Article
Engineering, Mechanical
Alan T. Nettles, William E. Guin, Isabelle Sadowski
Summary: This study presents experimental results showing that the CAI testing results of aluminum honeycomb core sandwich structure are influenced by material direction. Previous research has shown different CAI strengths, and this study further reveals the cause of this difference, which is the change in ply sequence of the face sheet material.
JOURNAL OF SANDWICH STRUCTURES & MATERIALS
(2022)
Article
Engineering, Multidisciplinary
S. Z. H. Shah, P. S. M. Megat-Yusoff, S. Karuppanan, R. S. Choudhry, Israr Ud Din, A. R. Othman, K. Sharp, P. Gerard
Summary: The damage tolerance of a unique resin-infused thermoplastic 3D-FRC is compared to a conventional resin-infused thermoset 3D-FRC in terms of compression after impact tests and finite element simulations. The thermoplastic 3D-FRC demonstrates higher damage tolerance due to its insensitivity to impact energy levels and gradual reduction in critical buckling compared to the significant compromise in properties seen in the thermoset 3D-FRC. This higher damage tolerance is attributed to local plastic deformation of the thermoplastic matrix and better interfacial adhesion at the impact site.
COMPOSITES PART B-ENGINEERING
(2021)
Article
Engineering, Mechanical
Alan T. Nettles, Baxter W. Barnes, William E. Guin, James P. Mavo
Summary: This study presents experimental results of compression after impact (CAI) testing of aluminum honeycomb core sandwich structure with face sheets made of co-cured T1100/3960 quasi-isotropic carbon/epoxy at different loading angles. The study found that the specimens loaded at +22.5 degrees and -22.5 degrees had similar CAI strength compared to the specimens loaded in the 0 degrees direction, while the specimens loaded in the 90 degrees direction had 16% lower CAI strength. Additional specimens loaded at +45 degrees showed intermediate CAI strength values between the 0 degrees and 90 degrees direction.
JOURNAL OF SANDWICH STRUCTURES & MATERIALS
(2023)
Article
Mechanics
Haowei Zhang, Huiming Ding, Di Yang, Qiang Xu, Yicheng Ma, Yunbo Bi
Summary: This study investigated the influence of Z-pin insertion angles (60 degrees, 75 degrees and 90 degrees) on the behavior and failure modes of compression after impact (CAI) for composite laminates. Different laminates with Z-pins at various angles were impacted and then tested under compression load until failure. The results showed that the effects of Z-pin insertion angles on CAI behavior and failure modes depended on the layups and impact energies. The 90 degrees Z-pin was found to be the most effective in improving CAI strength for both [0/90]4s and [45/ 0/-45/90]2s laminates. Decreasing Z-pin insertion angles reduced the enhancement of CAI strength, particularly for [0/90]4s laminates at higher impact energies. This study provides new insights into the effect of Z-pin insertion angles on the CAI failure mechanism and performance of composite laminates.
COMPOSITE STRUCTURES
(2023)
Article
Materials Science, Composites
Joseph O'Gara, Michael D. Sangid
Summary: The use of composites in aircraft structures requires a slow growth criteria and an appropriate similitude parameter to assess their life. This study examines the interconnected damage growth mechanisms in different layups and explores the efficacy of proposed similitude parameters in capturing slow crack growth. The results demonstrate the need to analyze similitude parameters across various sample geometries and stress states to understand composite material fatigue performance in aerospace applications.
COMPOSITES SCIENCE AND TECHNOLOGY
(2023)
Article
Engineering, Aerospace
Valeriy I. Trushlyakov, Vladislav A. Urbansky, Vadim V. Yudintsev
Summary: The concept proposes reducing environmental impact post-emergency cutoff of the liquid-propellant engine by utilizing an onboard propellant gasification system to control the launch vehicle's motion and guide it to a safe landing area. The system forces gasification of residual propellant using hydrogen peroxide, with vaporized propellant and helium used in thrusters for motion control. The design parameters are selected based on the first law of thermodynamics, and a simulation example demonstrates its effectiveness.
JOURNAL OF SPACECRAFT AND ROCKETS
(2021)
Article
Engineering, Aerospace
Yongwei Wang, Deng Zhou, Gang Yan, Zhuangjie Wang
Summary: This study investigates the residual mechanical properties of honeycomb sandwich composite structures after a lightning strike, using simulated tests and numerical predictions.
Article
Materials Science, Multidisciplinary
Abu Saifullah, Lei Wang, Antigoni Barouni, Khaled Giasin, Colin Lupton, Chulin Jiang, Zhongyi Zhang, Aldo Quaratino, Hom N. Dhakal
Summary: This study investigated the low velocity impact properties and damage propagation mechanism of rotationally moulded skin-foam-skin sandwich structures, comparing the effects of different foam material densities. The results demonstrated that sandwich structures with lower density foam material showed better impact properties and residual strength than those with higher density foam material.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2021)
Article
Mechanics
George Irven, Adam Whitehouse, Declan Carolan, Alexander Fergusson, John P. Dear
Summary: The methods of improving the toughness of the bond between a foam core and a carbon fibre face-sheet in a sandwich structure were investigated. It was found that introducing machined grooves in the foam and using core-shell rubber particles to toughen the face-sheets resulted in significant improvements in bond toughness. Additionally, using aramid fiber-reinforced foam as the core of the sandwich structure also contributed to enhancing the interface bond toughness and promoting R-curve behavior during crack propagation.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Materials Science, Composites
Zhenyu Wu, Kang Wang, Lin Shi, Xiaoying Cheng, Yanhong Yuan
Summary: In this paper, the impact resistance and damage tolerance of triaxial braid structure laminates at different positions were studied. Results showed that the triaxial braided fabric with quasi-isotropic properties on the impact side caused more significant matrix cracks and larger damage areas. The study provided valuable reference for failure analysis and structure optimization of composite laminates.
POLYMER COMPOSITES
(2023)
Article
Mechanics
Xinying Zhu, Wei Chen, Lulu Liu, Kailong Xu, Gang Luo, Zhenhua Zhao
Summary: This paper investigates the impact resistance and damage tolerance of 2D triaxially braided composites and 3D angle-interlock woven composites panels using high-velocity impact tests and compression after impact tests. Both materials show similar impact resistance but different damage patterns. X-ray CT scanning reveals the spatial variation in damage morphology caused by high-velocity impact.
COMPOSITE STRUCTURES
(2023)
Article
Engineering, Mechanical
Moeen S. Rajput, Magnus Burman, Stefan Hallstrom
Summary: Composite sandwich materials offer high bending performance-to-weight ratios, but are susceptible to impact damages which can significantly reduce their load-bearing capability. This study compared three different test methods for impact assessment and found that CAI-SS test method is recommended for post impact strength assessment of finite size plates with significant impact damage. CAI-SW test method may be more relevant for large sandwich panels with relatively small impact damages due to inclusion of panel asymmetry effects, while BAI test method could be an alternative to CAI but requires long specimens and is demanding and expensive. A finite element model with progressive damage evolution was used to estimate post impact strength, showing good agreement with experiments.
JOURNAL OF SANDWICH STRUCTURES & MATERIALS
(2022)
