Proceedings of the XII International Symposium on Dynamic Problems of Mechanics (DINAME 2007), Varoto, P. S. and Trindade, M. A. (Editors), ABCM, Ilhabela, SP, Brazil, February 26 - March 2, 2007 A Study of the Dynamic Behavior for Low Velocity Impact on Thin Composite Laminates Volnei Tita 1 , Jonas de Carvalho 2 and Dirk Vandepitte 3 1 Department of Materials, Aeronautical and Automobilist Engineering - School Engineering of São Carlos - University of São Paulo (Brazil) 2 Department of Mechanical Engineering - School Engineering of São Carlos - University of São Paulo (Brazil) 3 Department of Mechanical Engineering - PMA Division - Katholieke Universiteit Leuven (Belgium) Abstract: During the last two decades, research on the development of structural components with high crashworthiness has been carried out by the automobile, aeronautics, naval, trains and elevators industries. Many kinds of components have been made using composite materials, because these materials can absorb high amount impact energy and can guarantee the survival of the passengers. However, the dynamic behavior of composite laminates is very complex because there are many concurrently phenomena during composite laminate failure under impact load. Fiber breakage, delaminations, matrix cracking, plastic deformations due contact and large displacements are some effects which should be considered when a structure made from composite material is impacted by a foreign object. Thus, an investigation of the low velocity impact on thin composite laminates of epoxy resin reinforced by carbon fiber is presented. The study shows the technology to manufacture the specimens and the set-ups of equipments to make dynamic experimental tests using a drop-tower instrumented. Afterwards, non- destructive evaluation (NDE) using ultrasonic C-Scan was carried out in order to determine the main kind of failure. The influence of stacking sequence and energy impact were investigated using load-time histories, displacement-time histories and energy-time histories as well as images from NDE. Finally, indentation tests were developed and the quasi-static results were compared to dynamic results, verifying the inertia effects when thin composite laminate were impacted by foreign object with low velocity. Keywords: impact, experimental tests, NDE, composite laminates NOMENCLATURE E = energy, J m = impact mass, kg v = velocity, m/s t = time, s h = impact height, m Subscripts o relative to initial velocity i relative to impacter exp relative to experimental tests INTRODUCTION During the last years, criteria of automobile and aircraft projects have been more and more rigorous for component developed in order to absorb impact energy. Research on the development of structural components with high crashworthiness has been carried out not only by the automobile and aeronautics industries, but also, by naval, trains and elevators industries. The project concept for structural components with high crashworthiness depends on the crash resistance concept described by Kindervater and Georgi (1993). The crash resistance concept is based on the energy absorption capacity and structural integrity. For developing a project that reaches those requirements, it should change the material and/or architecture of the component. However, changes on the architecture can cause increase of costs and/or of weights, reducing the performance of the structure. The weight increase is not attractive for the aircraft development, because it reduces the aircraft performance; so, it’s more interesting change the material. Nowadays, many kinds of components have been made using composite materials, because these materials can absorb high amount impact energy and can guarantee the survival of the passengers. However, the dynamic behavior of composite laminates is very complex, because there are many concurrently phenomena during composite laminate failure under impact load. Fiber breakage, delaminations, matrix cracking, plastic deformations due to the contact and large displacements are some effects which should be considered when a structure made from composite material is impacted by a foreign object. Therefore, it’s very common to find research works about this issue at the literature, for example : Levy Neto and Al-Quereshi (1986); Oñate et al. (1991); Cairns and Lagace (1992); Farley and Jones (1992); Haug and De Rouvray (1993); Belingardi, Gugliota and Vadori (1998); Collombet, Lalbin and Lataillade (1998); Gottesman and Girshovich (1998); Vicente, Béltran and Martínez (2000); Kindervater et al. (2000); Tita and Carvalho (2001); Kostopoulos et al. (2002); Lopresto and Caprino (2002). Thus, this work is other scientific contribution that shows an experimental investigation of the low velocity impact on thin composite laminates plates of epoxy resin reinforced (matrix) by carbon fiber (reinforcement). This study describes the technology to manufacture the specimens and the set-ups of equipments to make dynamic experimental