Search

Purpose: The vibration energy transmission characteristics of laminated composite plates with straight or variable angle fiber paths subjected to distributed force excitations are explored in this paper. Methods: The dynamic responses as a function of frequency are calculated and evaluated using proposed analytical approach and numerical finite element (FE) method based on the first-order shear deformation theory. The FE model is firstly verified by the analytical method and used for the composite plates with various fiber paths. The FE-based structural intensities analysis is carried out to predict the energy transmission and distribution patterns on the laminated composite plates with various fiber paths. Results: The structural intensity streamlines and vectors representation explicitly offer the information of the energy sources, energy sinks and detailed vibration energy distribution and transmission paths. The fiber paths have significant influences on the dynamic responses and energy transmission paths. The results reveal that tailoring fiber paths could lead to the formation of vortex-type flows with low vibration levels. Conclusion: According to the structural intensity fields at the specific excitation frequencies, the tailorable fibers in the forced area or unforced area and curvilinear fibers could be tuned for vibration mitigation.

This paper proposes a deep learning model that can quickly design the lay-up scheme of a type IV hydrogen storage vessel, which is called physics-constrained generative adversarial networks (PCGANs). A third-party neural network is built to evaluate the model's training output, and a tailored penalty is appended to the generator's loss function to introduce the physical constraint. This penalty term occurs when the metrics of lay-up design fail to meet the requirement, thus changing the training direction of the model. The datasets are generated randomly with the finite element method, and the training process can be visualized by converting one-dimensional lay-up information into a two-dimensional matrix. The results demonstrate that PCGANs has achieved an impressive effect; not only can it generate designs that meet the target, but also it has good accuracy in the prediction. The optimal proposal is selected from the different design options provided by PCGANs, and the burst pressure is 158 MPa, which is 2.25 times greater than the working pressure. The optimal design has 33 hoop layers, the weight of which is reduced by 16.33 % when compared with traditional netting theory, and the maximum fiber accumulation thickness of 24.68 mm, which is reduced by 42.11 %.

Carbonaceous micro-/nanoparticles are efficient infrared attenuation agents which may enhance the thermal insulation properties of polymeric foams by reducing the radiation heat transfer. The effects of low-concentration (≤0.5 wt %) multiwalled carbon nanotubes and micrographite (mGr) on the extrusion foaming of semicrystalline polyethylene terephthalate were investigated in this study. It is shown that the heterogeneous nucleation induced by the carbonaceous particulates would greatly affect the nonisothermal crystallization behavior during extrusion foaming. The rheology test results revealed that the melt strength of CPET composites was low above 235 °C but radically increased when the melt cooled down because of fast crystallization. Consequently, this phenomenon was beneficial to the cell growth and expansion at high melt temperatures because the increased melt viscosity could stabilize the cellular structure during the quenching stage. CPET/carbonaceous particulate composite foams showed high crystallinity, excellent IR absorption, and enhanced thermal insulation properties.

Light weight, high sound insulation property polymers have vast potential application in aviation, auto industry and the military application. Pressure induced flow (PIF) process form multi-layer-oriented structure in polymer matrix, and supercritical CO2foaming (ScCO2) introduce gas into the matrix and increase the impedance mismatch between the phase, both of them enhance the polymer sound insulation property. In this paper, the sound insulation property of polypropylene (PP)/polyolefin elastomer (POE) blended composites prepared by the PIF process and the ScCO2foaming were measured using the impedance tube. The sound insulation property is up to 103.56 dB in the frequency band of 1000–6000 Hz for 5 mm PIF PP/POE foam material, which it is 67.15 dB higher than PP/POE foam. By employing the multi-scale ffinite element analysis (FEA) modeling method, one two-phase FEA model of the monolith of 0.1 mm size and another 29 mm diameter bulk sample were developed based on SEM image of PIF PP/POE foamed materials at different scales. The monolith FEA model provided the effective material property for bulk sample. The finite element calculation results were consistent with the experimental result, verified the validity of the FEA modelling approach. The FEA simulation results reveal that the multi-layer-oriented structure of PIF material introduce the multi-layer impedance mismatch inside each monolith, and incident sound wave is reflected by those impedance mismatch, and this mechanism produce the high sound insulation property of PIF PP/POE foam materials.

With the rapid development of high-power and high-energy density lithium-ion batteries, thermal safety has become a critical issue. Due to the fast microstructure change triggered by heat, thermosensitive polymers have aroused increasing attention as thermal shutdown material candidates to prevent the thermal runaway of lithium-ion batteries. In this work, a sandwich-structured polyacrylonitrile/polyethylene oxide/polyacrylonitrile (PAN/PEO/PAN) fibrous membrane with prompt thermal shutdown properties and high thermal stability is prepared using electrospinning technique. The inner layer of the fusible PEO fibrous membrane impart the composite separator with a prompt thermal shutdown function at 80 °C. Meanwhile, the outer layer of the heat-resistant PAN membrane remains thermally stable, even at 200 °C. The large buffering temperature difference (120 °C) between the thermal shutdown temperature and the thermally stable temperature of the composite separator is wider than most of the reported separators and effectively enhances the thermal safety of the lithium-ion batteries. In addition, the PAN/PEO/PAN separator exhibits a higher porosity, better electrolyte wettability, larger ionic conductivity, and lower interfacial resistance compared with a commercial polypropylene/polyethylene/ polypropylene (PP/PE/PP) separator. Moreover, the coin cells assembled by the PAN/PEO/PAN separator presents stable cycle performance and excellent rate capability. Therefore, the novel PAN/PEO/PAN membrane shows great potential as a promising candidate for much safer lithium-ion battery separators.