For the purpose of renewable materials applications, Curauá fiber treated with 5% sodium hydroxide was added to high-density biopolyethylene, using an entirely Brazilian raw material of sugarcane ethanol. Polyethylene grafted with maleic anhydride was used as a compatibilizer. With the addition of curauá fiber, the crystallinity was reduced, possibly due to interactions in the crystalline matrix. A positive thermal resistance effect was observed for the maximum degradation temperatures of the biocomposites. When curauá fiber was added (5% by weight), the morphology showed interfacial adhesion, greater energy storage and damping capacity. Although curauá fiber additions did not affect the yield strength of high-density bio polyethylene, its fracture toughness improved. With the addition of curauá fiber (5% by weight), the fracture strain was greatly reduced to about 52%, the impact strength was also reduced, suggesting a reinforcing effect. Concomitantly, the modulus and the maximum bending stress, as well as the Shore D hardness of the curauá fiber biocomposites (at 3 and 5% by weight), were improved. Two important aspects of product viability were achieved. First, there was no change in processability and, second, with the addition of small amounts of curauá fiber, there was a gain in the specific properties of the biopolymer. The resulting synergies can help ensure more sustainable and environmentally friendly manufacturing of automotive products.

Metallic materials undergo many metallurgical changes when subjected to welding thermal cycles, and these changes have a considerable influence on the thermo-mechanical properties of welded structures. One method for evaluating the welding thermal cycle variables, while still in the project phase, would be simulation using computational methods. This paper presents an evaluation of the temperature field and residual stresses in a multipass weld of API 5L X80 steel, which is extensively used in oil and gas industry, using the Finite Element Method (FEM). In the simulation, the following complex phenomena were considered: the variation in physical and mechanical properties of the material as a function of the temperature, welding speed and convection and radiation mechanisms. Additionally, in order to characterize a multipass weld using the Gas Tungsten Arc Welding process for the root pass and the Shielded Metal Arc Welding process for the filling passes, the analytical heat source proposed by Goldak and Chakravarti was used. In addition, we were able to analyze the influence of the mesh refinement in the simulation results. The findings indicated a significant variation of about 50% in the peak temperature values. Furthermore, changes were observed in terms of the level and profile of the welded joint residual stresses when more than one welding pass was considered.

This work aims to experimentally study the drying of agricultural products using microwaves, with particular reference to grains. Microwave drying experiments were carried out with paddy rice grains in natura (BRSMG Conai variety) for three levels of incident microwave power per mass of fresh grain (6.27, 14.63 and 22.99 W/g). Results of grain drying and heating kinetics are presented and analyzed. It was verified that the ideal average moisture content for grain storage and marketing, 15% (d.b.), occurred at 20 min (6.27 W/g), 13 min (14.63 W/g) and 7 min (22.99 W/g), and that the equilibrium moisture content of the samples reached 4.4%, 2.7% and 1.9%, at 310, 180 and 110 min, for each of the three power levels studied, respectively. The drying with the highest absorbed power caused discoloration of the grains at the end of the drying process.

With advances in technology, the generation of electrical energy through the harvesting of energies dissipated in the form of mechanical vibration, known as power harvesting, has received increasing attention in recent decades. It is undoubtedly an interesting means to power systems with low energy consumption. This research aims to evaluate an energy generation system based on the piezoelectric effect activated by mechanical excitation and develop a system capable of powering devices and sensors for temperature monitoring in a practical situation, such as in an engine room, aiming to ensure its safe operation. Two transducers subjected to vibrational excitation were evaluated, and then an energy generation system using a buck DC-DC converter circuit was assessed. The transducer was connected to the input of the board, the microcontroller to the output, and the LM35 temperature sensor along with the battery was used to ensure the circuit’s autonomy. Additionally, the Attiny85 microcontroller was programmed to perform temperature monitoring tasks in a continuous low-energy-consumption mode. The obtained spectral analysis results showed a maximum generation power of 8.88 mW for the PZT-5H transducer and 3.3 mW for the P5-13B transducer. The use of LTC3588-1 increased the autonomy of the monitoring system by 64.3% and reduced the system’s usage time in cases of temperature anomalies by 50%.

Vegetable fibers have inspired studies in academia and industry, because of their good characteristics appropriated for many technological applications. Sisal fibers (Agave sisalana variety), when extracted from the leaf, are wet and must be dried to reduce moisture content, minimizing deterioration and degradation for long time. The control of the drying process plays an important role to guarantee maximum quality of the fibers related to mechanical strength and color. In this sense, this research aims to evaluate the drying of sisal fibers in an oven with mechanical air circulation. For this purpose, a transient and 3D mathematical model has been developed to predict moisture removal and heating of a fiber porous bed, and drying experiments were carried out at different drying conditions. The advanced model considers bed porosity, fiber and bed moisture, simultaneous heat and mass transfer, and heat transport due to conduction, convection and evaporation. Simulated drying and heating curves and the hygroscopic equilibrium moisture content of the sisal fibers are presented and compared with the experimental data, and good concordance was obtained. Results of moisture content and temperature distribution within the fiber porous bed are presented and discussed in details. It was observed that the moisture removal and temperature kinetics of the sisal fibers were affected by the temperature and relative humidity of the drying air, being more accentuated at higher temperature and lower relative humidity, and the drying process occurred in a falling rate period.