Visco-hyperelastic model with damage for simulating cyclic thermoplastic elastomers behavior applied to an industrial component

In this work a nonlinear phenomenological visco-hyperelastic model including damage consideration is developed to simulate the behavior of Santoprene 101-73 material. This type of elastomeric material is widely used in the automotive and aeronautic sectors, as it has multiple advantages. However, there are still challenges in properly analyzing the mechanical phenomena that these materials exhibit. To simulate this kind of material a lot of theories have been exposed, but none of them have been endorsed unanimously. In this paper, a new model is presented based on the literature, and on experimental data. The test samples were extracted from an air intake duct component of an automotive engine. Inelastic phenomena such as hyperelasticity, viscoelasticity and damage are considered singularly in this model, thus modifying and improving some relevant models found in the literature. Optimization algorithms were used to find out the model parameter values that lead to the best fit of the experimental curves from the tests. An adequate fitting was obtained for the experimental results of a cyclic uniaxial loading of Santoprene 101-73

The effective-thickness concept in laminated-glass elements under static loading

Laminated glass is a sandwich element consisting of two or more glass sheets, with one or more interlayers of a polymer such as polyvinyl butyral (PVB). The static response of sandwich elements such as laminated-glass beams and plates can be modeled using analytical or numerical models in which the glass is usually modeled as linear-elastic and the PVB as linear-viscoelastic material, respectively. As a way to simplify the laminated-glass calculations, the concept of effective thickness has been recently proposed, which allows the calculation of laminated-glass beams as monolithic beams using an apparent or effective thickness. In this work, equations for the effective thickness of laminated-glass beams are derived from the analytical model proposed by Koutsawa and Daya and the results provided by this model are compared with the models of Bennison et al. and Galuppi and Royer-Carfagni. Finally, some static experimental tests were performed on several laminated-glass beams under distributed loading in order to validate the predictions of the model

Study of the Time-Temperature-Dependent behaviour of PVB: application to laminated glass elements

The mechanical behavior of laminated glass elements is governed by material properties of the interlayer, the Polyvinyl Butiral (PVB) being the most used interlayer material in these elements. PVB is a viscoelastic material whose mechanical properties (Young’s modulus, shear modulus, etc.) depend mainly on the load application time and the temperature. Thus an adequate mechanical characterization of the PVB must be performed in order to predict the response of laminated glass elements with a good accuracy In this work, PVB specimens were subjected to static relaxation tests and to dynamic experimental tests (frequency domain) at different temperatures from -〖15〗^o C to 〖50〗^o C using a DMTA equipment. Then the curves at different temperatures were related using the William-Landel-Ferry (WLF) Time-Temperature Superposition (TTS) model to obtain the mastercurve of both the time and frequency domain Young’s moduli of the PVB. Finally, a viscoelastic Prony based model was fitted to the experimental data and used, afterwards, to simulate numerically the static and dynamic behaviour of different laminated glass elements at different temperatures. The numerical simulations were compared with the static and dynamic experimental results achieving a good accuracy in both the static deflections and the natural frequencies. With respect to the damping, the discrepancies are less than 22%

Modified Disk-Shaped Compact Tension Test for Measuring Concrete Fracture Properties

Abstract A new approach for measuring the specific fracture energy of concrete denoted modified disk-shaped compact tension (MDCT) test is presented. The procedure is based on previous ideas regarding the use of compact tension specimens for studying the fracture behavior of concrete but implies significant modifications of the specimen morphology in order to avoid premature failures (such as the breakage of concrete around the pulling load holes). The manufacturing and test performance is improved and simplified, enhancing the reliability of the material characterization. MDCT specimens are particularly suitable when fracture properties of already casted concrete structures are required. To evaluate the applicability of the MDCT test to estimate the size-independent specific fracture energy of concrete (G F ), the interaction between the fracture process zone of concrete and the boundary of the MDCT specimens at the end of the test is properly analyzed. Further, the experimental results of G F obtained by MDCT tests for normal- and high-strength self-compacting concrete mixes are compared with those obtained using the well-established three-point bending test. The procedure proposed furnishes promising results, and the G F values obtained are reliable enough for the specimen size range studied in this work

Dimensionamiento de placas de acristalamiento para edificios mediante un modelo probabilístico de rotura

Se propone un modelo para el dimensionamiento a rotura de acrisíalamientos de vidrio, que, partiendo del estado tensional, obtenido medianíe la teoría de placas con grandes deformaciones, y de la distribución empírica de defectos superficiales en el vidrio, utiliza criterios de Mecánica de la Fractura para predecir probabilisticamente la rotura. La validez del modelo ha podido ser contrastada experiment aiment e en placas de diferentes espesores y con variadas relaciones geométricasA model for the design of glass plates to failure is presented, which, based on the theory of plates with gross deformations for the calculation of the stress state as well as on the empirical flaws statistical distribution in the glass surface, applies fracture Mechanics criteria to establish a probabilistic prediction of failure. The validity of the model has been experimentally proved for plates with different thicknesses and geometric characteristic