Geometrical optimization of bumper beam profile made of pultruded composite by numerical simulation Giovanni Belingardi, Alem Tekalign Beyene ⇑ , Ermias Gebrekidan Koricho Politecnico di Torino, Department of Mechanical and Aerospace Engineering, Corso Duca degli Abruzzi, 24, 10129 Torino, Italy 1 article info Article history: Available online 7 March 2013 Keywords: Bumper beam Optimization Pultruded Composite structures Geometrical profile Crashworthiness abstract In addition to their high specific strength and specific stiffness composite materials possess high energy absorption capability, that makes them an interesting alternative material for developing automotive safety component, when to combine weight saving and crashworthiness is highly desirable. In this work E-Glass/epoxy pultruded bumper beam is considered and its energy absorption capability is compared with steel and E-Glass/epoxy fabric composite. Furthermore, low velocity impact finite ele- ment simulations are performed using ABAQUS, in order to optimize beam section profile and beam cur- vature for crashworthiness. Results show that, pultruded bumper beam has comparable energy absorption capability with respect to the steel normal production solution. The new composite solution, after appropriate optimization of bumper beam section profile and beam curvature, exhibits yields improved energy absorption characteristics; the development of progressive failure mode leads to lower mean crash load and almost constant force diagram whose value is close to the maximum peak load. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Automobile bumper subsystem is the frontal and rear structure of the vehicle that has the purpose of energy absorption during low velocity impact. Usually, bumper subsystem consists of bumper transverse beam, stays, impact-absorbing materials in the form of structural components and a cover. Among those elements, the bumper beam is the main structural component; it is expected to be deformable enough to absorb the impact energy, in order to reduce the risks of injury for pedestrians and other vulnerable road users, but, at the same time, it should also have sufficient strength to protect the nearby vehicle components. Therefore, during bum- per beam design process the challenging task is to obtain the opti- mal characteristics, since there is a tradeoff between strength and deformability. Due to their enhanced physical and mechanical properties, such as high specific strength, both in static and impact loading condi- tions, and high specific stiffness (light weightiness), composite materials could be an interesting candidate material for this com- ponent. When designing with composite material, it is always needed to select the type of production technology that will be used in manufacturing, as this choice will affect deeply both the cost and the production rate. As a matter of fact, up to now, in spite of composite attractive mechanical features, their relatively low volume of production and high material cost have hindered their intensive application for automotive structural components [1]. Pultrusion is a rapidly growing, cost-effective and fully auto- mated manufacturing process for producing constant cross-section composite profiles. Generally, pultruded profiles have straight axis, however some recent experience [2] shows that profiles with curved axis could also be produced with this manufacturing tech- niques. For the structural component of interest, pultrusion could be an appropriate composite manufacturing technology able to ob- tain high production rate with reasonable low manufacturing cost. Besides, pultruded products have very high quality in terms of geometry accuracy and degree of consistency of mechanical prop- erty due to process automation, they have also quite high compres- sion strength, due to precise filament alignment and high fiber volume fraction (up 85% by weight) [1,3], as a consequence of material curing under tension. Nowadays, pultruded composite products have become widely used in structural engineering applications and have been selected for some road components like roadside safety structures [4] and vehicles safety components such as bumper and crush box [4–6], where these structures are submitted to impact loading conditions. Published experimental studies [7,8] show that pultruded com- posites (PFRP) have comparable and sometimes even higher values of energy absorption capability and impact force resistance with respect to steel and aluminum. The impact responses and damage mechanisms for the whole group of composite materials is rela- tively more complex than conventional materials and it depends 0263-8223/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.compstruct.2013.02.013 ⇑ Corresponding author. Tel.: +39 3490828957. E-mail addresses: giovanni.belingardi@polito.it (G. Belingardi), alem.beyene@- polito.it (A.T. Beyene), ermias.koricho@polito.it (E.G. Koricho). 1 http://www.polito.it. Composite Structures 102 (2013) 217–225 Contents lists available at SciVerse ScienceDirect Composite Structures journal homepage: www.elsevier.com/locate/compstruct