EFFECTS OF TEMPERATURE ENVIRONMENT ON MODE II INTERLAMINAR FRACTURE TOUGHNESS IN ASYMMETRIC CFRP LAMINATES

When delamination occurs in CFRP laminates due to impact, a portion of the laminate structure becomes asymmetric across the delamination in the thickness direction, resulting in a coupling effect of in-plane and out-of-plane deformations. Thus, it is important to evaluate the coupling effects on the interlaminar fracture toughness and fracture mechanism in CFRP laminates. In addition, it is necessary to withstand practical temperature environments. Based on Verchery's approach, the authors intentionally prepared asymmetric laminates with non-zero and zero-coupling components in the classical lamination theory to evaluate the effects of coupling components on the interlaminar fracture toughness in CFRP laminates. In this study, the Mode II interlaminar fracture toughness of CFRP laminates with and without coupling components in the stiffness matrix was measured by the end notched flexure (ENF) test in the temperature range from room temperature to 80°C. The relationship between the temperature and the interlaminar fracture toughness was quantitatively evaluated. Fracture surface observation was also conducted to clarify the fracture mechanism.

Pyrolysis of wheat and barley straw

Pyrolysing agricultural crop residues and other biomass constitutes a newer method of transforming often difficult, waste materials into a novel type of soil amendment/additive. Simultaneously, this process also makes it possible to exploit part of the energy released in the agricultural production. Biochar, viewed as the solid product of biomass pyrolysis, is a remarkable, porous material, rich in carbon. Two agricultural crop residues, such as wheat and barley straw, were selected for the experimental studies. The results indicate that the practical temperature for the production of biochar from the two explored materials occurs in the vicinity of 600 °C. Starting at this temperature, the biochar produced complies safely with the principal European Biochar Certificate standards (EBC 2012). Thus, for the wheat straw and barley straw – originated char, the content of the carbon amounts to 67.2 and 67.0 mass %, the atomic ratio H : C is as large as 0.032 and 0.026, and the specific surface area amounts to 217 and 201 m²·g^–1, respectively.

Practical Nozzle Temperature Control Method for Robot FDM Printing System

Fused Deposition Modeling (FDM) technology in 3D printing has beendeveloped for many years. In this paper, a robot FDM 3D printingsystem is proposed and the nozzle temperature control issue isfocused primarily. The temperature measurement adopts a data driven modeling method andthe parameters of the measurement model are trained by the particle swarm optimization algorithm. A practical temperature control method is presented in which thetemperature control of nozzle is divided into two periods. Duringthe temperature flying period, the heating voltage is givenaccording to the current temperature value and its varying trend. In thefalling time of nozzle temperature, the corresponding controlvoltage value is provided correspondingly. Based on this practical control strategy, a partdesigned with Solidworks software is printed using the robot FDM printing system which validates theeffectiveness of the practical temperature control method.

The Quantitative Research of Interaction between Key Parameters and the Effects on Mechanical Property in FDM

The central composite design (CCD) experiment is conducted to evaluate the interaction between parameters and the effect on mechanical property. The layer thickness, deposition velocity, and air gap are considered as the key factors. Three disparate levels of the parameters are utilized in the experiment. The experimental results suggest that all these parameters can affect the bonding degree of the filaments, which affects the final tensile strength of the specimen. A new numerical model is built to describe the cooling process of the fused filament, which shows a perfect coherence with the practical temperature file of filament. It reveals what the forming mechanism of the bonding between filaments is and how these parameters act on final tensile strength of the specimen of this way from temperature. It is concluded that the parameters are not working alone; in fact they all contribute to determining the mechanical property, while the air gap plays the predominant role in determining the final tensile strength, followed by layer thickness as the next predominant factor, and the effect of deposition velocity is the weakest factor.

Preparation and Study on Temperature-Resistance Environment-Friendly Ink Based on Natural Pigment and Soybean Oil

Traditional ink based on natural pigment and soybean oil has disadvantages of poor temperature adaptive in application process. This project broke the limitations that stocks printing with traditional ink based on natural pigment and soybean oil could not be used for heating. Developing practical temperature-resistance environment-friendly ink based on natural pigment and soybean oil is of great importance. The experiment introduced the silicone material, and made full use of its characteristic. The Si-O bond of silicone can be 121 kcal/mole, and its molecular bond can not be broken down at a high temperature (or exposure to radiation). The property of high temperature resistance mainly depends on its unique functional group or long polymer chain structure. The experiment studied temperature resistance environment-friendly ink's performance in color, in order to improve its practical application value.

Adaptive Neuron-Like Control of Time-Delay Systems Enhanced with Feedforward and Supervisory Strategies

Tracking control of nonlinear systems with significant delay effects has been the focus of intensive research. In this paper, we propose an effective supervised adaptive control scheme to tackle the problem. The scheme is composed of an adaptive control part of two neuron-like models with delay effects and a supervisory control part to enhance robustness against disturbance and model uncertainties. A design methodology based on the Lyapunov analysis is presented. Experimental results obtained from a practical temperature control system show that not only is the design procedure conceptually simple but also the control performance is also excellent when compared with the traditional PD controller. Also, the feedforward term is able to provide extra improvement in the regulation performance.