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Markina-Xemein, Spain

Kano-Ibarretxe J.,Leartiker | Hernandez R.,Leartiker | Mondragon I.,University of the Basque Country
ECCM 2012 - Composites at Venice, Proceedings of the 15th European Conference on Composite Materials | Year: 2012

The present work aimed to analyze the influence of interphase adhesion level on micro and macro-mechanical behavior of unidirectional basalt fibre epoxy composites. The study was evaluated for as-received, unsized and γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane and γ-methacryloxypropyltrimethoxysilane sized fibres and their composites. The unsized fibres were obtained by immersion in acetone and its efficiency was evaluated by scanning electron microscopy (SEM). The micromechanical characterization was carried out by means of monofilament tensile test, Weibull twoparameter distribution and microbond test. The macro-mechanical characterization was made by tensile and three-point bending tests. The scatter of the microbond results and the similar tensile and flexural results for as-received and unsized composites, lead to further sizing elimination method efficiency study. Source


Mars W.V.,Endurica LLC | Isasi M.,Leartiker | Arriaga A.,Leartiker | Plaza J.,Cikatek
Constitutive Models for Rubber IX - Proceedings of the 9th European Conference on Constitutive Models for Rubbers, ECCMR | Year: 2015

Because rubber’s stiffness evolves with damage, the effects of a given operating cycle depend not only on the initial amplitude of the cycle, but also on how the cycle is controlled. Displacement and force controlled fatigue tests have been made on an elastomeric automotive exhaust mount, showing that at a given initial starting level, force controlled tests lead to shorter fatigue life than displacement controlled tests. Using these measurements, the effect of control mode on fatigue life has been analyzed. The analysis takes into account the evolution of stiffness with cycles, and it shows how fatigue performance for both cases derives from the same underlying fatigue crack growth properties. The results provide insight on how results from one test control mode may be applied to infer results from other test control modes. © 2015 Taylor & Francis Group, London, UK. Source


Iturrondobeitia M.,University of the Basque Country | Ibarretxe J.,University of the Basque Country | Guraya T.,University of the Basque Country | Zaldua A.M.,Leartiker | Lopez-De-Uralde J.,University of Deusto
ECCM 2012 - Composites at Venice, Proceedings of the 15th European Conference on Composite Materials | Year: 2012

Polymer layered silicate nanocomposites' final properties are highly dependent on their reinforcement composition, morphology, dispersion, orientation and distribution through the polymeric matrix. Poly(lactic acid) (PLA) based nanocomposites were prepared using different silicate systems (Cloisite 20A and 30B) and varying extrusion (screw rotation rate) and injection molding (injection rate) parameters. Mechanical properties, specially elastic modulus and resilience, increased when Cloisite 30B was used. These results were verified by measuring micro-structural parameters (agglomeration factor and distances) from TEM images. The nanocomposites showing higher elastic modulus and resilience were the ones containing Cloisite 30B, which also shoed smaller agglomeration factor and lower and narrower distribution of the distances to the closest neighbours. Source


Arriaga A.,Leartiker | Pagaldai R.,Leartiker | Zaldua A.M.,Leartiker | Chrysostomou A.,London Metropolitan University | O'Brien M.,London Metropolitan University
Polymer Testing | Year: 2010

A 20% mineral filled polypropylene homopolymer (Hifax XM2 U16 from LyondellBasell Industries) was studied. Correlation between experimental impact tests of components and tensile tests on specimens with simulations in ANSYS and LS-DYNA were conducted. The main goal of these tests was to evaluate the validity of elasto-plastic strain rate sensitive constitutive models implemented in both codes. Initially, strain localisation or necking phenomena were studied by simulating quasi-static tensile tests in ANSYS. An iterative method was used to match experimental force-displacement curves and so obtain true stress-strain curves as input for finite element analysis programs. Subsequently, the experimental impact testing of parts manufactured from the mineral filled polypropylene was simulated in ANSYS and LS-DYNA. It was found that the viscoplastic strain rate sensitive Perzyna's model compared well with test results from force-time and velocity-time curves but did not adequately describe the high force levels developed, particularly at the start of the tests. Additional sensitivity analyses in terms of element type, contact stiffness and mesh density were also carried out. Yield stress rate dependency was evaluated using the material model MAT 24 in LS-DYNA and, in addition, yield stress and elastic modulus rate dependency was evaluated with MAT 19. Both models offered very similar results. An initial attempt to simulate failure was also carried out with MAT 24. © 2009 Elsevier Ltd. All rights reserved. Source


Arrillaga A.,Leartiker | Kareaga Z.,Leartiker | Retolaza E.,Leartiker | Zaldua A.M.,Leartiker
Gummi, Fasern, Kunststoffe | Year: 2011

The rubber industry requires a practical technique to determine the degree of cure achieved in moulded parts. In this context tests regarding the swelling characteristics and residual exothermicity (by means of DSC) can be considered as helpful techniques. DSC measurements, however, were not useful due to the low exothermicity of the formulations having been investigated. The cure variation of a NR crosslinked with sulphur and an EPDM crosslinked with peroxide was examined using swelling measurements in cyclohexane. It could be observed that swelling results agreed with data from rheological tests as well as modulus values from tensile testing. The method was also applied to an industrial rubber part to evaluate differences in the degree of cure across the part thickness. Source

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