Applied Composite Materials最新文献

This paper presents a study on manufacturing a range of hybrid laminated structures made of thermoplastic polyurethan (TPU), glass fibre reinforced plastic (GFRP), styrene-butadiene rubber (SBR) and metal mesh materials, and further on investigating the structural response of the TPU based composite sandwich laminated structures. These laminated structures were tested under quasi-static perforation and low velocity impact loading to determine their structural responses and energy absorption characteristics. It has been shown that three-layer and five-layer laminates with lay-ups of GFRP-TPU-GFRP or TPU-GFRP-TPU and GFRP-TPU-GFRP-TPU-GFRP or TPU-GFRP-TPU-GFRP-TPU subjected to quasi-static perforation demonstrate an increased peak load and stiffness with the core thickness from 1 to 4 mm. Also, the TPU core laminates show a superior ductility in comparison to their GFRP core counterparts. The energy absorption values of the three-layer and five-layer TPU and GFRP based laminated structures under low velocity impact are higher than those under quasi-static loading due to strain-rate effect. However, the hybrid laminates with SBR and wire mesh as a core do not give much improvement on the impact perforation resistance of the laminates with the different size of wire mesh, as metal mesh plays a less important role in the laminated structures to resist perforation. In overall, TPU-GFRP-TPU-GFRP-TPU structure with 4mm thick GFRP core demonstrates the highest peak force, and the GFRP-TPU-GFRP-TPU-GFRP structure with 4mm thick TPU core offers the highest energy absorption.

With the widespread application of sandwich composites, the performance of the core structure in the sandwich composites has received particular attention. As the typical representative of lightweight core structure, honeycombs have excellent designability and are widely used. The emerging fibre reinforced composite honeycombs have incomparable performance advantages over traditional metal or chopped fibre honeycombs. This means that design, manufacturing technologies and performance evaluation of composite honeycombs are important. In this review, grid, hexagonal, Kagome, corrugated and origami structure honeycombs and their associated manufacturing strategies have been summarised. In addition, more attention has been paid to textile structure composite honeycombs fabricated by weaving, braiding, or knitting techniques. Their mechanical performances have been extensively reviewed to clarify the relationship between structure and properties. Based on existing studies, the damage mechanisms of composite honeycomb structures are found to be insufficient; especially for the load-bearing mechanisms and predicting methods for honeycombs, which is a challenge for further development. This review hopes to inspire the innovation in fibre reinforced composite honeycombs from the view of structure design and performance evaluation.

Polyurethane foam (PUF) is widely utilized in cushioning and energy absorption applications, owing to its cellular structure, that provides high damage tolerance under compression. This study explores the dynamic mechanical properties of PUF with varying densities under different strain rates. Uniaxial compression tests were conducted on PUF samples with densities of 120, 200, and 300 kg/m³ using an improved Split Hopkinson Pressure Bar (SHPB) system and a universal testing machine, with loading rates ranging from 10^–4 to 2000s⁻¹. Results show that PUF properties are influenced by density and strain rate. Higher density foams have higher strength but lower densification strain. All samples demonstrated strain rate sensitivity, where higher rates leading to increased strength and decreased densification strain. Based on the aforementioned findings, a dynamic constitutive model was developed to incorporate the influences of density, strain, and strain rate. This model effectively predicts the mechanical behavior of PUF and offers valuable insights for engineering applications requiring impact protection and energy absorption.

Aluminum/epoxy resin interpenetrating phase composites (IPCs) were directly strengthened by adding glass fiber of varying content (80 wt%, 100 wt%, 120 wt% and 140 wt%) inside the epoxy resin. The macro and micro structures of IPCs were intact, and the interface between aluminum and epoxy resin was well combined. As the content of glass fiber increased, the compressive strength of epoxy resin increased, but the failure was advanced, while IPCs displayed the opposite trend. IPCs exhibited three compression deformation modes, namely plastic deformation of aluminum, resin fracture and interface debonding. The digital image correlation and infrared thermal imager were used to characterize the apparent principal strain distribution and temperature distribution of IPCs to verify the deformation modes. The surface temperature damage evolution of IPCs included the rapid temperature rise stage, steady temperature stage and slight temperature drop stage, respectively, mainly corresponding to the linear elastic stage, plateau stage and densification stage in the stress-strain curves.

Three-dimensional woven tubular composites (3DWTCs) exhibit exceptional structural integrity and superior interlaminar shear resistance, making them highly promising candidates for energy absorption components in a wide range of applications. This paper aims to evaluate the impact response of 3DWTCs with varying structures through low-velocity impact experiments. Three types of 3DWTCs, namely shallow cross-linked (SCL), shallow-crossed curved joint (SCCL), and through orthogonal (TO), were fabricated using basalt fiber bundles and epoxy resin via the vacuum-assisted resin transfer molding (VARTM) process. Low-velocity impact tests were conducted at energy levels of 5, 10, and 20 J. To evaluate the damage characteristics of 3DWTCs, the observations were analyzed in terms of load-time curves, load-displacement curves, energy-time curves, and failure morphologies. The results indicate that the SCL structure exhibits superior impact resistance, followed by SCCL, while the TO structure displays the lowest. This study provides valuable insights into the potential applications of 3DWTCs in the aerospace industry and other sectors.

This study presents an analytical model of low-velocity impact on composite plates, possessing either flat or cylindrical shapes. The overall plate`s stiffness properties are varied with an additionally assembled Ω-stringer and embedded shape memory alloy wires in the composite material, using only the shape memory effect. This analytical approach enables a low-effort but sufficiently accurate design of low-energy-impacted structures. Comprehensive analytical equations are developed based on the inclusion of the stringer effect on the curved panels. For both stringer-stiffened and non-stiffened plate models, parameter variations regarding the impact and shape memory alloy (SMA) wire integration are conducted. The effects can be classified as changes in essential and acquired stiffness. Our results indicate that SMAs improve the energy absorption capability of stiffened composite panels.

The production of high-quality fiber reinforced polymer parts is an important aspect in several industrial areas. However, due to unavoidable uncertainties in material and manufacturing processes, the part quality scatters. One important aspect here is the fiber orientation, being crucial for the thermo-mechanical properties of the part and being influenced by the uncertain material state and process conditions. Process simulations are an important tool for predicting the fiber orientation, but state-of-the-art simulations are normally deterministic and represent only one specific case. Performing enough deterministic simulations to model manufacturing uncertainties requires high numerical effort. Therefore, this work presents methods to quickly and efficiently approximate the fiber orientation under varying material and process parameters, requiring only a few simulations as input. Different schemes for approximation are evaluated and compared with each other and with 3D process simulations.

Combination of experimental testing and numerical analysis is suggested to determine static mechanical properties of the auxetic honeycombs realized via material extrusion. Special specimens, which consist of two honeycombs plates and three steel plates, are used to analyze experimentally shear mechanical properties of honeycombs. Shear testing is simulated using the finite elements software ANSYS. The tests on tension of honeycombs are carried out. These tests are simulated by finite elements software. Plasticity of the honeycomb material and geometrically nonlinear deformations of the honeycomb walls are accounted in honeycomb model. The experimental data and calculations results are close.

Herein, a coupled elastoplastic-damage analytical model is developed to analyze the effect of the plasticity of the resin on the failure behavior of 3D woven composites (3DWC). The proposed model is numerically simulated using different unit-cells of 3DWC and is verified by experimental data. The results show that under warp loading, the plasticity of the resin has a greater effect on component damage, and both the plasticity and the damage show an alternating iterative propagation mode; in contrast, under weft loading, the plasticity of the resin has a lesser effect on component damage, and both show an independent extension pattern. This work provides a guidance for the strength design of 3DWC structures such as aero-engine fan blades, which demonstrates significant engineering implications.