Applied Mechanics and Materials Vols. 24-25

Abstract: This paper presents the results of an experimental study carried out to assess the effects of cumulative damage on the strain response of open-hole (notched) quasi-isotropic [45/0/-45/90]4s E-glass/913 epoxy laminate specimens under quasi-static tension, and constant amplitude tension-tension, compression-compression and tension-compression cyclic loading conditions. In-plane surface strain was measured as a function of applied load and loading cycles for quasi-static and cyclic loading respectively using digital image correlation (DIC) and compared with strain gauge, fibre Bragg grating (FBG) optical sensor and contact extensometer strain measurements. DIC proved successful in monitoring local (near the hole) and global strains, providing critical information on the changes in strain distribution resulting from damage formation and growth incurred.

Abstract: This paper is a study of the drop weight impact behaviour of small sandwich panels of carbon epoxy skins with aluminium honeycomb and titanium alloy micro-lattice cores. A series of experimental tests have shown that the specific impactor penetration behaviours are similar for both cores. The reasons for this are a result of the detailed deformation and rupture behaviour of the two types of core. The deformation and rupture mechanisms of honeycomb and micro-lattice structures will be discussed in general terms, and these observations will be used to inform discussion of actual deformation and rupture in the panel tests. In this way, micro energy absorbing mechanisms will be related to panel performance, and conclusions on the way forward for improved penetration performance using other core materials and geometries will be identified.

Abstract: The present work can be regarded as a first step toward an integrated modelling of mould filling during injection moulding process of polymer matrix composites and the resulting material behaviour under service loading conditions. More precisely, the emphasis of the present research is laid on the development of a mechanical model which takes into account the processing-induced microstructure and is capable to predict the mechanical response of the material. In the Part I, a set of experiments which captures the mechanical behaviour of an injection moulded short fibre reinforced under different strain histories is described. Three mechanical testing are conducted: Dynamic Mechanical Analysis (DMA), uniaxial tension and simple shear. Tests show that the material exhibits complex responses mainly due to non-linearity, anisotropy, time/rate-dependence, hysteresis and permanent strain. Moreover, the relaxed state of the material is characterized by the existence of a so-called anisotropic equilibrium hysteresis independently of the prescribed strain rate.

Abstract: This paper presents an alternative to the theoretical classic teaching methods generally used in Strength of Materials or Solids Mechanics. It introduces a dynamic and interactive process, with emphasis in the use of ESA-Experimental Stress Analysis, especially strain gauges and photo-elasticity. In addition to the didactic and practical experiments, the students used all their energy and creativity to develop the interesting results presented here, such as, experimental device for measuring displacement, Buckling, Spaghetti and Popsicle sticks Bridges, Stress analysis in a cylinder block and Mini Baja project.