The present study aims to design an experimental test bench to analyze and control a smart structure system composed of a woven fiberglass laminate plate with shape memory alloy (SMA) actuators instilled on the surface. The aim of this design is to accurately augment the strain of the composite plate. Finite element analysis was employed to model the composite structure and determine the placement of the SMA actuators in order to produce the desired structural response efficiently with minimum power consumption. Due to the nonlinear behavior of the SMA actuator, it will be critical to incorporate a feedback control system that is able to accurately morph the structure by changing the strain of the composite structure. A Proportional-Integral-Derivative (PID) controller was designed to improve its tracking performance. Simulation on the control system showed that the PID controller produced acceptable response and managed to reduce steady state error for different types of input. The PID controller was then implemented in the experimental setup to control the smart composite plate. Results from the experiment illustrates that the smart structure system that has been designed performed effectively and the strain value of the composite structure can be controlled accurately.
The present study was aimed to assess the protective effect of aqueous extract of Spinacia oleracea leaves (AESO 250, 500, and 1,000 mg/kg, p.o.) in inflammatory bowel disease using acetic acid- and ethanol-induced colitis in mice and indomethacin-induced enterocolitis in rats. The preliminary phytochemical analysis and further high performance thin layer chromatographic (HPTLC) analysis and phytochemical tests of HPTLC bands confirmed the presence of flavonoids and tannins in AESO. In acute oral toxicity study, administration of AESO (5,000 mg/kg, p.o.) did not show any sign of toxicity and mortality. The treatment with AESO significantly increased body weight, decreased diarrhea with bloody stools, increased blood hemoglobin and plasma total protein, and decreased serum and ileum or colon malondialdehyde content and attenuated the extent of lesions and ameliorated the histological injury of mucosa in all paradigms. The most prominent effects were evident for AESO 1,000 mg/kg. The results of the present study revealed that AESO was effective in attenuating almost all the symptoms of IBD in experimental paradigms. The effect might be due to the antioxidant activity of the flavonoids present in the AESO.
There are several input variables that can be used to control the deflection of a shape memory alloy (SMA) composite system such as the resistance or temperature of the SMA actuator and position or strain of the composite plate. It is common to control the actuator directly, however SMA is nonlinear and it exhibits hysteresis which may result in inaccurate control of the plate's deflection. Thus controlling the plate's deflection may be more effective by using input measurement from the composite plate. The aim of this study is to propose the optimal feedback variable deflection control of a fiberglass composite plate system using SMA actuators. Two types of variables were investigated which were temperature of the SMA actuator and strain of the composite plate. The feedback control system for SMA actuated composite plate was implemented with different types of sensors; thermocouple and strain gauge. When current is supplied to the SMA actuator, it will contract and produce a force that will deflect the composite plate. During this process, the SMA actuator's temperature changes with the current supplied and the strain of the composite plate changes during deflection due to torsion and bending. Thus, it is proposed to use these variables as the input to the feedback of the smart composite plate system to control the movement of the plate. Using the adopted control technique of the experimental test bench presented here, the strain feedback system was more effective and energy efficient compared to the temperature feedback for the control of morphing composite plate.
The present study is proposing a deflection control of a fiberglass composite plate system using shape memory alloy (SMA) actuators. The aim of this study is to determine the optimal placement of sensor for the feedback smart composite plate system. Strain measurement on the composite plate was chosen as the input variable for the feedback system. The change in strain on the composite plate was different at all locations on the plate during deflection. Thus, six strain gauges were placed at three positions i.e. tip, mid and root of the plate, at angle 0° and 45° in order to measure the change in strain at these locations and determine which is the best location to produce accurate control of the plate. The performance of the plate using these input variables were compared and analyzed by conducting experiments which required the plate to be deflected using the control system. In order to evaluate the performance of the controller under varying conditions, disturbances were also added to the experiments. The disturbances introduced were similar to those faced by aircraft during flight that is wind flow at varying velocities conducted in the wind tunnel. From the experimental results, it was found that the tip of the plate had the highest change in strain value and the control using input from the strain gauge located there produced the best performance as compared to input from strain gauges located at mid and root of the plate. However, in the presence of airflow, it was found that the best control performance was using feedback from the strain gauge located in the middle of the plate.
This paper presents a variable deflection control of a fiber glass composite plate system using shape memory alloy (SMA) actuators. The technique on changing the camber of plate needs to be developed as it is the most investigated approach of shape morphing. Gradual changes of the camber along the span can create controllable twisting of the composite plate. The necessary camber change is pursued either by reconfiguration of the underlying structure or the shape changing of the composite plate or smart composite. In this proposed platform, strain gauges are used to measure the strain of the plate in a single cantilever mode while nickel titanium (NiTi) Shape Memory Alloy (SMA) wires are used as actuators to actuate the composite plate, which are controlled using Proportional-Integral-Derivative (PID) controller. In this research six strain gauges were placed at different location of the plate: tip, mid and root part of the plate. From the experimental result, it was found that the mid part of the plate had the highest change in strain value and the control system using input from the strain gauge located there produced the best performance compared to those located at the tip and root of the plate.
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