Nowadays cellular materials are receiving great attention for their excellent mechanical properties, being applied in energy absorbers or in structural components having optimized mass distribution. In this paper stretch-dominated lattice structures have been considered. A 3D periodic lattice structure of different cell size, TPMS (triply periodic minimal surface), made of epoxy resin by DLP technology was studied. Compression tests at different strain rate (10-3 to 103 1/s) have been performed and a constitutive model to assess the experimental findings has been calibrated.
Laser Metal Deposition is an Additive Manufacturing process with an extreme potential in large-scale metal production. Among the printable metals, the Inconel 625 has found a wide variety of cutting-edge applications in the aerospace, defense and space sectors. Thus, knowledge of mechanical properties under static and dynamic conditions is fundamental. In this work, the quasi-static and dynamic compression behaviour of Inconel 625 obtained by Laser Metal Deposition is presented. The curves of printed Inconel 625 showed a change in slope in the work hardening phase, which is due to the mechanics of the dislocation motion. Therefore, a modified Two-Stage Hollomon power-law is proposed to model this specific mechanical behaviour, which identifies a threshold strain that delimit two different hardening behaviours. Furthermore, Johnson-Cook and Cowper-Symonds models were used to represent the effect of strain rate and temperature on the material properties. A variable strain rate sensitivity along the compression strain was found. Hence, double sensitivity terms were introduced into the Two-Stage Hollomon power-law, allowing to reproduce the dynamic behaviour of Inconel 625.
This paper investigates the nonlinear dynamic behaviour of a cantilever beam made of composite material without and with lumped mass fixed along its length. The analysis compares the results coming from analytical and numerical modelling with experimental observations. The nonlinearities due to large vibration amplitude and to inertia effect are taken into account. An extended analytical approach has been developed, which is able to provide the approximate solution of the transverse displacement and the first nonlinear frequency with nonlinear terms up to fifth order. Then, an exact expression for the backbone curve is also proposed. In the experimental tests, a high-speed imaging technique has been used to capture the vibrating behaviour of a composite beam. Then, the nonlinearity of the acquired data is determined by the Fitting Time History technique. A Finite Element model has been implemented in order to validate the developed procedure. Finally, the results obtained by the analytical, experimental, and numerical methods are compared. It is found that the analytical formulation describes the real backbone curve of the beam, which is hardening. Accuracy of the analytical method decreases as the lumped mass increases.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.