Experimental investigation of the dynamic fracture of a class of RT-PMMAs under impact loading
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ORIGINAL PAPER
Experimental investigation of the dynamic fracture of a class of RT-PMMAs under impact loading Norazrina Mat Jali · Patrice Longere
Received: 24 April 2019 / Accepted: 30 July 2020 © Springer Nature B.V. 2020
Abstract The present work aims to investigate experimentally the crack arrest capability and dynamic fracture mechanisms under impact loading of three commercial, rubber-toughened (RT) PMMA grades differing by their rubber nano-particle concentration and resulting Charpy impact toughness. For that purpose, Kalthoff and Winkler (KW)-like impact tests were performed using gas launcher considering impact velocities ranging between 20 and 100 m/s. A high-speed camera was used to record the projectile/specimen interaction and the progressive failure of the specimen. The fracture surfaces of the fragments were observed using a scanning electron microscope (SEM). It is seen that the higher the impact velocity the larger the number of fragments. On the other hand, it is shown that increasing the rubber nano-particle concentration favors the crack arrest capability under impact loading by promoting inelastic deformation, reducing the crack propagation velocity, limiting crack multi-branching, and reducing the number of fragments. Keywords RT-PMMA · Crack arrest · Impact loading
N. M. Jali · P. Longere (B) Université de Toulouse, ISAE–SUPAERO, ICA (CNRS 5312), 31400 Toulouse, France e-mail: [email protected] N. M. Jali Faculty of Engineering, National Defence University of Malaysia, 57000 Kuala Lumpur, Malaysia
1 Introduction In the transportation sector in general and in the aeronautical one in particular, the engineering materials have to meet the most demanding requirements in terms of weather-resistance, protection against UV radiation and toughness in nominal service, and in terms of crash-, collision- and impact-resistance during accidental overloads. In parallel, they have to be as light as possible in a view of reducing the CO2 emissionsinduced environmental impact. In this context, we are interested here in transparent engineering materials as glass surrogate candidates. Due to its transparency, shatter-, scratch- and weatherresistance and favorable processing conditions, PMMA is widely used as a substitute for inorganic glass. This accordingly makes PMMA a suitable material for windows protecting against bullet and blast (Hsieh et al. 2004). PMMA has thus been widely used in military aviation since World War II to replace the glass for airplane windows. It also can replace the usage of glass for windshield and armour protection. PMMA has accordingly been applied in cockpits, portholes, windshields, exterior lighting and helicopter windscreens, see e.g. Hu et al. (2016). This substitution helps increase the value in terms of safety because it proves to be a much safer material in battle situations for aviators (Gilbert et al. 1995). The application of PMMA as structural material in various industrial sectors requires a good knowledge
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