Damage Analysis of Composite Sheet Under Thermal Load

The goal of this research is to carry out a 3-dimensional finite detail approach evaluation of a composite plate cracked under thermal loading. The results of the mechanical properties of the composite, the orientation angle of the fibers, the geometric form of the plate, the thermal loading and the crack length had been studied to show their influence on the variation of the integral J. It is concluded that the integral J increases with the increase of crack size, temperature variation and reduce in fiber orientation perspective (e). To complete the work a probabilistic analysis was carried out.

Tunable acoustic metasurface based on PVDF/PI unimorph sheets

We propose a tunable metasurface unit based on a composite sheet of polyvinylidene fluoride (PVDF) membrane and polyimide tape. The deformation of the sheet can be adjusted by applying a voltage to the PVDF membrane, and the phase of reflected acoustic waves can be continuously tuned and spans the full 2π range. Various acoustic functions can be achieved by applying different voltages on the units. The experiment is also given to prove the unit’s ability to control acoustic waves. Our design shows the possibility of dynamically manipulating acoustic waves and designing integrated acoustic devices by piezo-membrane micromechanical system.

Batch Manufacturing of Split-Actuator Micro Air Vehicle Based on Monolithic Processing Technology

Microrobots have a wide range of applications. The rigid–flexible composite stereoscopic technology based on ultraviolet laser cutting technology is primarily researched for the design and manufacture of microrobots and has been used to fabricate microscale motion mechanisms and robots. This paper introduces a monolithic processing technology based on the rigid–flexible composite stereoscopic process. Based on this process, a split-actuator micro flapping-wing air vehicle with a size of 15 mm × 2.5 mm × 30 mm was designed. We proposed a batch manufacturing method capable of processing multiple micro air vehicles at the same time. The main structure of 22 flapping-wing micro air vehicles can be processed at the same time within the processing range of the composite sheet with an area of 80 mm × 80 mm, and the processing effect is good.

Impact Toughness of Hybrid Carbon Fiber-PLA/ABS Laminar Composite Produced through Fused Filament Fabrication

Nowadays, the components of carbon fiber-reinforced polymer composites (an important material) are directly produced with 3D printing technology, especially Fused Filament Fabrication (FFF). However, such components suffer from poor toughness. The main aim of this research is to overcome this drawback by introducing an idea of laying down a high toughness material on the 3D-printed carbon fiber-reinforced polymer composite sheet, thereby making a hybrid composite of laminar structure. To ascertain this idea, in the present study, a carbon-reinforced Polylactic Acid (C-PLA) composite sheet was initially 3D printed through FFF technology, which was then laid upon with the Acrylonitrile Butadiene Styrene (ABS), named as C-PLA/ABS hybrid laminar composite, in an attempt to increase its impact toughness. The hybrid composite was fabricated by varying different 3D printing parameters and was then subjected to impact testing. The results revealed that toughness increased by employing higher layer thickness and clad ratio, while it decreased by increasing the fill density, but remained unaffected due to any change in the raster angle. The highest impact toughness (23,465.6 kJ/m2) was achieved when fabrication was performed employing layer thickness of 0.5 mm, clad ratio of 1, fill density of 40%. As a result of laying up ABS sheet on C-PLA sheet, the toughness of resulting structure increased greatly (280 to 365%) as compared to the equivalent C-PLA structure, as expected. Two different types of distinct failures were observed during impact testing. In type A, both laminates fractured simultaneously without any delamination as a hammer hit the sample. In type B, the failure initiated with fracturing of C-PLA sheet followed by interfacial delamination at the boundary walls. The SEM analysis of fractured surfaces revealed two types of pores in the C-PLA lamina, while only one type in the ABS lamina. Further, there was no interlayer cracking in the C-PLA lamina contrary to the ABS lamina, thereby indicating greater interlayer adhesion in the C-PLA lamina.

Effect of Pulsed Light Irradiation on Patterning of Reduction Graphene Oxide-Graphene Oxide Interconnects for Power Devices

Reduction graphene oxide (r-GO) lines on graphene oxide (GO) films can be prepared by a photocatalytic reduction and photothermal reduction method. A mechanism of partial GO reduction by pulsed photon energy is identified for preparing patterned rGO-GO films. The photocatalytic reduction method efficiently reduces GO at low photon energies. The successful production of a patterned rGO-GO film without damage by the photo thermal reduction method is possible when an energy density of 6.0 or 6.5 J/m2 per pulse is applied to a thin GO film (thickness: 0.45 μm). The lowest resistance obtained for a photo-reduced rGO line is 0.9 kΩ sq−1. The GO-TiO2 pattern fabricated on the 0.23 μm GO-TiO2 composite sheet through the energy density of each pulse is 5.5 J/m2 for three pulses.

A DIGITAL TWIN FOR AUTOMATED LAYUP OF PREPREG COMPOSITE SHEETS

The composite sheet layup process involves stacking several layers of a viscoelastic prepreg sheet and curing the laminate to manufacture the component. Demands for automating functional tasks in the composite manufacturing processes have dramatically increased in the past decade. A simulation system representing a digital twin of the composite sheet can aid in the development of such an autonomous system for prepreg sheet layup. While Finite Element Analysis (FEA) is a popular approach for simulating flexible materials, material properties need to be encoded to produce high-fidelity mechanical simulations. We present a methodology to predict material parameters of a thin-shell FEA model based on real-world observations of the deformations of the object. We utilize the model to develop a digital twin of a composite sheet. The method is tested on viscoelastic composite prepreg sheets and fabric materials such as cotton cloth, felt and canvas. We discuss the implementation and development of a high-speed FEA simulator based on the VegaFEM library. By using our method to identify sheet material parameters, the sheet simulation system is able to predict sheet behavior within 5 cm of average error and have proven its capability for 10 fps real-time sheet simulation.

A Digital Twin for Automated Layup of Prepreg Composite Sheets

The composite sheet layup process involves stacking several layers of a viscoelastic prepreg sheet and curing the laminate to manufacture the component. Demands for automating functional tasks in the composite manufacturing processes have dramatically increased in the past decade. A simulation system representing a digital twin of the composite sheet can aid in the development of such an autonomous system for prepreg sheet layup. While Finite Element Analysis (FEA) is a popular approach for simulating flexible materials, material properties need to be encoded to produce high-fidelity mechanical simulations. We present a methodology to predict material parameters of a thin-shell FEA model based on real-world observations of the deformations of the object. We utilize the model to develop a digital twin of a composite sheet. The method is tested on viscoelastic composite prepreg sheets and fabric materials such as cotton cloth, felt and canvas. We discuss the implementation and development of a high-speed FEA simulator based on the VegaFEM library [29]. By using our method to identify sheet material parameters, the sheet simulation system is able to predict sheet behavior within 5 cm of average error and have proven its capability for 10 fps real-time sheet simulation.