In this paper we have created some composites reinforced with corn cob powder and the matrix was made by a combination between Resoltech 1050 resin with its Resoltech 1058 hardener. For the composites manufacturing, we have used the manual casting technique. For the new manufactured composites, we have determined the mechanical properties from the tensile test according to ASTM D3039: Young modulus, breaking strength and elongation at break. We have also molded samples for the compression test according to ASTM D695-15 and we have determined the breaking strength. The tensile and compression tests were made on universal testing machines. In the end, we have determined also the dynamic mechanical properties for the studied material by clamping the samples at one edge and leaving the samples unconstrained at the other edge. At the unconstrained edge we have placed a Bruel&Kjaer accelerometer which recorded the samples free vibrations. From the free vibrations recording and Euler-Bernoulli theory, we have determined the next dynamic mechanical properties: damping factor per unit mass and length, eigenfrequency, dynamic modulus of elasticity, loss factor and dynamic rigidity. From the experimental results, we have obtained increased breaking strength values for the proposed material at compression compared to the tensile test. Compared to similar materials studied in the engineering literature, we have obtained increased compression breaking strength.

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This paper presents the mechanical properties for sandwich core strips with a 60% sandarac combination core and 40% Resoltech 1050 epoxy resin with 1055 hardener, and the upper and lower layers reinforced with cotton, silk and linen fabric, and the matrix is a combination of 60% dammar resin and 40% Resoltech 1050 epoxy resin with 1055 hardener. For these materials, there is determined: static mechanical properties from tensile stress (Young elastic modulus, yield strength, breaking strength) and chemical composition by energy dispersive spectroscopy analysis with an scanning electron microscope. It is observed that the dammar resin, in all the cases, has increased mechanical characteristics compared to sandarac. Also, the samples reinforced with cotton show better mechanical properties compared to the ones reinforced with flax and silk.

In this paper, some new original hybrid sandwich beams were built in this way: the core is made with polypropylene honeycomb and the reinforcement is made with steel wire mesh. The connection between the reinforcement and the core was made with epoxy resin. The aim of this study is to create a beam from classic materials but combined in a way to obtain a new and original structure. The static experimental conditions are characterized by bending loading of the beams and the determination of statically stiffness. The dynamic parameters were determined from the beams free vibrations. The next experimental montage was used: the beams were clamped at one end and were left free at the other end. At the free end, a Bruel&Kjaer accelerometer with 0.04 pC/ms−2 sensitivity was placed. A force was applied at the free end to bend the beams and after bending, the force was cancelled and the beams were left to freely vibrate. From the free vibrations recording, the next mechanical parameters were determined: the eigenfrequency of the first eigenmode, the damping factors per unit mass and per unit length, the loss factor, the dynamic stiffness and the dynamic Young modulus.

In this paper, some composite materials were built in this way: the reinforcement is made with natural fibers (there were used two types of natural fibers in this way: hemp and cotton) and the matrix is made from epoxy resin. The Resoltech 1050 epoxy resin is used, with its Resoltech 1050 hardener. The casting was made at room temperature and the matrix was applied using the brush. The static experimental conditions are characterized by tensile loading of the build specimens and the determination of statically Young modulus. There was used an Instron Universal testing machine and the force-extension curves were obtained. The dynamic parameters were determined from the bars free vibrations. The next experimental montage was used: the bars were clamped at one end and were left free at the other end. At the free end, a Bruel&Kjaer accelerometer with 0.04 pC/ms−2 sensitivity was placed in order to record the beams dynamic response. A force was applied at the free end to bend the beams and after bending, the force was cancelled and the beams were left to freely vibrate. The accelerometer was connected to a signal conditioner Nexus and the signal conditioner was connected to a data acquisition system SPIDER 8 made by Hottinger Baldwin Messtec. The acquisition system was connected to a notebook and the experimental parameters were obtained through CATMAN EASY software. From the free vibrations recording, the next mechanical parameters were determined: the eigenfrequency of the first eigenmode, the damping factors per unit mass and per unit length, the loss factor and the dynamic Young modulus.