Featured Cover Yoshioka, Hideki; Noguchi, Takafumi; Kobayashi, Kyoichi ...
Fire and materials,
12/2021, Volume:
45, Issue:
8
Journal Article
Peer reviewed
The cover image is based on the Original Article Development of a New Intermediate‐scale Box Test on Sandwich Panel Products Compared with ISO 13784‐1 Room Test and EN 13501‐1 Classification System ...by Hideki Yoshioka et al., https://doi.org/10.1002/fam.2984.
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It is widely known that the availability of lightweight structures with excellent energy absorption capacity is essential for numerous engineering applications. Inspired by many biological structures ...in nature, bio-inspired structures have been proved to exhibit a significant improvement over conventional structures in energy absorption capacity. Therefore, use of the biomimetic approach for designing novel lightweight structures with excellent energy absorption capacity has been increasing in engineering fields in recent years. This paper provides a comprehensive overview of recent advances in the development of bio-inspired structures for energy absorption applications. In particular, we describe the unique features and remarkable mechanical properties of biological structures such as plants and animals, which can be mimicked to design efficient energy absorbers. Next, we review and discuss the structural designs as well as the energy absorption characteristics of current bio-inspired structures with different configurations and structures, including multi-cell tubes, frusta, sandwich panels, composite plates, honeycombs, foams, building structures and lattices. These materials have been used for bio-inspired structures, including but not limited to metals, polymers, fibre-reinforced composites, concrete and glass. We also discussed the manufacturing techniques of bio-inspired structures based on conventional methods, and adaptive manufacturing (3D printing). Finally, contemporary challenges and future directions for bio-inspired structures are presented. This synopsis provides a useful platform for researchers and engineers to create novel designs of bio-inspired structures for energy absorption applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
Composite sandwich panels have a vast heritage and are commonly employed in various fields. The space industry is not an exception and often space structures and experiments use this type of ...panels. This paper represents an effort toward the development of a design procedure for space-born sandwich panels. The here-presented work has been performed on a real test case: the structural sandwich panel of a scientific space mission. In this preliminary phase, classical methodologies were used to ensure the satisfaction of the mechanical requirements and for the minimization of the panel mass and dimensions. Tools such as Finite Element (FE) were employed to help with the design. Increasingly detailed models were developed and used to design the space panels. In addition, this work describes the future roadmap of the project.
•The paper conducted impact tests on the Nomex honeycomb sandwich panels.•Impact simulation models of Nomex honeycomb sandwich panels were established.•Indentation prediction model during the impact ...process was established.•The influences of various parameters in the impact process were explored.•Structural and impactive parameters have corresponding influences on the impact performance.
Through experiments and numerical simulation, the dynamic mechanical behaviors and mechanical properties of Nomex honeycomb sandwich panels under impact loads were investigated. On this basis, the effects of the density of honeycomb cores, face-sheet thickness, punch diameter, and impact energy on impact loads and failure modes were explored. The predicted contact time, impact load, and failure mode were consistent with the test results. Results showed that face-sheet thickness exhibited an extremely significant influence on the impact resistance of Nomex honeycomb sandwich panels; the density of honeycomb cores exerted a certain effect on the structural stiffness; the punch diameter and impact energy also influenced the mechanical properties and failure modes of sandwich panels.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
When laser-welded metal sandwich panels are subjected to out-of-plane cyclic three-point bending loads, cracks may initiate at the interface and eventually lead to fatigue debonding due to the ...influence of the geometric discontinuity of the unfused zone. This debonding behavior occurs between the upper and lower face panels of the sandwich panel and can easily cause structural failure without being noticed. Therefore, in practical engineering, an effective method is needed to accurately calculate this debonding process. Focusing on the interfacial fatigue debonding problem of I-type three-core metal sandwich panels, this paper conducts numerical simulations of the fatigue debonding behavior of sandwich panels based on the bilinear cohesive zone model and carries out fatigue debonding experiments to verify the accuracy of the simulations. The fatigue test results show that cracks initiate at the laser weld joint between the face panel and core panel of the sandwich panel and eventually propagate through the entire interface. This study proposes a fatigue debonding simulation method based on the bilinear cohesive zone model. Through comparisons between simulations and numerical results, it is verified that this method can accurately calculate the interfacial fatigue debonding process and life of sandwich panels, which are difficult to observe in practical engineering applications. This research has important engineering significance.
•Debonding tests of type-I sandwich panels are conducted using cyclic three-point bending loads.•Fatigue crack propagates along the laser-welded interface leading to debonding of the sandwich panel.•Bilinear cohesive zone model is used to study the fatigue strength of laser-welded sandwich panels.•The proposed model can predict the fatigue debonding strength of laser-welded sandwich panels.
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Additive manufacturing of industrially-relevant high-performance parts and products is today a reality, especially for metal additive manufacturing technologies. The design complexity ...that is now possible makes it particularly useful to improve product performance in a variety of applications. Metal additive manufacturing is especially well matured and is being used for production of end-use mission-critical parts. The next level of this development includes the use of intentionally designed porous metals - architected cellular or lattice structures. Cellular structures can be designed or tailored for specific mechanical or other performance characteristics and have numerous advantages due to their large surface area, low mass, regular repeated structure and open interconnected pore spaces. This is considered particularly useful for medical implants and for lightweight automotive and aerospace components, which are the main industry drivers at present. Architected cellular structures behave similar to open cell foams, which have found many other industrial applications to date, such as sandwich panels for impact absorption, radiators for thermal management, filters or catalyst materials, sound insulation, amongst others. The advantage of additively manufactured cellular structures is the precise control of the micro-architecture which becomes possible. The huge potential of these porous architected cellular materials manufactured by additive manufacturing is currently limited by concerns over their structural integrity. This is a valid concern, when considering the complexity of the manufacturing process, and the only recent maturation of metal additive manufacturing technologies. Many potential manufacturing errors can occur, which have so far resulted in a widely disparate set of results in the literature for these types of structures, with especially poor fatigue properties often found. These have improved over the years, matching the maturation and improvement of the metal additive manufacturing processes. As the causes of errors and effects of these on mechanical properties are now better understood, many of the underlying issues can be removed or mitigated. This makes additively manufactured cellular structures a highly valid option for disruptive new and improved industrial products. This review paper discusses the progress to date in the improvement of the fatigue performance of cellular structures manufactured by additive manufacturing, especially metal-based, providing insights and a glimpse to the future for fatigue-tolerant additively manufactured architected cellular materials.
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Sandwich panels with triple layered graded honeycomb cores were tested under blast loading. The structural response was analyzed by using finite element software LS-DYNA after validation against the ...experiments. The structural deformation modes were classified into three types and the core layer deformation was divided into three regions. For the same value of impulse, a localized impulse led to severely localized deformation mode. A relatively evenly distributed impulse resulted in largely global bending deformation. Under the same loading, graded panels with the core of the largest relative density placed near the impact face suffered a smaller deflection than the panels with uniform core. Furthermore, for the same deformation mode the normalized back face sheet deflection increased linearly with impulse.
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Recently, metamaterials, sandwich panels, and a combination of both have shown potential for creating lightweight, load-bearing structures with good noise and vibration suppression properties. ...However, designing these structures is difficult due to the complex vibroacoustic innate physics and the need to balance conflicting requirements. Structural optimization methods can help address this multi-functional, multi-physical design challenge. While much research has been conducted on optimizing the materials and sizes of plates and sandwich cores, the systematic topological design of fully coupled vibroacoustic cores has not yet been explored. To address this gap, this work presents a topology optimization framework for the vibroacoustic design of sandwich structure cores, with the goal of minimizing sound transmission while constraining volume and structural stiffness. The framework is used to conduct a systematic design analysis, focusing on the dynamic behavior of the optimized structures. The versatility of the methodology is demonstrated by analyzing different targeted frequency ranges, different angles of incidence and the trade-off between the acoustic and structural performance. The resulting designs are lightweight, load-bearing, and achieve high sound transmission loss performance, exceeding the mass law by 15−40 dB in targeted frequency ranges of 500Hz in the interval between 1000Hz and 3000Hz.
•Systematic design analysis of sandwich structures is presented.•Topology optimization framework proposed for sound transmission minimization.•Vibroacoustic coupling considered in the optimization design space.•Trade-off between structural, acoustic and mass requirements investigated.•Versatility of framework shown by several numerical studies.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Global buckling failure should be avoided when designing a structure with the requirement of crashworthiness performance. This study characterises the quasi-static in-plane crushing of CF/EP ...composite sandwich panels by tailoring their bevel angles. A finite element model was developed describing the interlaminar and intralaminar damage of a composite sandwich panel; this model was validated by in-plane compression experiments. A numerical analysis and compression experiments were then performed to determine the responses and failure modes in the CF/EP composite sandwich panels with various bevel angles. The results showed that the global buckling-to-progressive failure transition under compression occurred in the composite sandwich panels when the bevel angle reached a critical value. A microscopic analysis showed that the composite sandwich panels with buckling failure behaviours exhibited an apparently classical post-buckling transverse shearing mode, while those with progressive failure presented individual lamina bending with inward and outward fronds. This study provides some useful data for the design of the crashworthiness of a sandwich composite panel by introducing a progressive failure mode.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Blast response of gradient honeycomb sandwich panels were examined.•Influence of core arrangement on the blast response were investigated.•The energy absorption of gradient cores was calculated.•The ...use of basalt FMLs can enhance the blast resistance of sandwich panels.
In this paper, the blast responses of fiber metal laminates (FMLs) and gradient aluminum honeycomb sandwich panels with FML as skins were experimentally investigated. The woven basalt fabric was chosen as the composite reinforcement in FMLs due to its excellent mechanical and eco-friendly properties. Five different core layer arrangements were considered for sandwich panels in the experiments by arranging honeycomb core layers with different cell geometric dimensions. The deformation/failure modes of sandwich panels were obtained in the experiments, in terms of FML face-sheets and gradient honeycomb cores. The energy absorption of gradient honeycomb cores was quantitatively analyzed by digitizing the deformation/failure region of cores. The results showed that the use of basalt FMLs as face sheets can greatly enhance the blast resistance of sandwich panels compared with that with aluminum sheets as skins. The blast resistance of gradient sandwich panels not only depends on the geometric dimensions and arrangements of core layers, but also related to the intensity of target load which will cause different deformation/failure mechanism of panels. Thus, in order to obtain the best blast resistance, a well-design gradient sandwich panel should have suitable core layer arrangements and geometry to satisfy the intensity of target blast load. The results obtained from current study can give valuable reference to the using of sandwich panels in engineering protection field.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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