Original Article Design and optimization of electric bus monocoque structure consisting of composite materials Pathawee Kunakorn-ong 1 , Kitchanon Ruangjirakit 2 , Pattaramon Jongpradist 1 , Sontipee Aimmanee 2 and Yossapong Laoonual 1,3 Abstract This paper proposes a novel design methodology for electric-bus structures by implementing the finite element method via ABAQUS TM and linear programming via MATLAB TM . A monocoque sandwich-structured fiber-reinforced composite bus with a maximum driving range of 300 km is conceived using the proposed methodology. The bus-body structure is designed based on safety criteria such as vehicle registration regulations, the strength of the bus structure under various driving conditions, bending- and torsion-stiffness requirements, and the rollover testing standard of UN ECE R66. A procedure developed to systematically conduct parametric studies by varying the core and face thicknesses of the sandwich structure of each component is presented. Multivariate functions are formulated to determine the correlations of structural responses with changes in geometric parameters. Linear programming is implemented to minimize the mass of the bus structure under design constraints. The proposed monocoque bus structure meets all requirements, and its body mass is 63.3% less than the benchmark value. Keywords Monocoque structure, electric bus, composite materials, finite element analysis, linear programming, bus design Date received: 6 October 2019; accepted: 13 March 2020 Introduction Climate change has become a serious global issue. The International Energy Agency (IEA) 1 proposed a two-degree-Celsius scenario (2DS), in which the aver- age global temperature increase by 2050 is limited to only 2  C. The transport sector is a significant con- tributor towards the success of 2DS, which aims for a reduction in CO 2 emission by 21%. The electric vehicles initiative (EVI) is a group of more than 10 countries and private-sector stakeholders that aims to encourage the adoption of electric vehicles (EVs) and increase the global stock of EVs. EVI anticipates an increase of the cumulative EV stock to 250 million by 2030. To be able to achieve the 2DS goal proper engin- eering analysis plays a very important role in the design and manufacturing of electric vehicles. The structures of EVs differ from those of conventional vehicles because EVs include heavy components such as batteries and do not have internal combustion engines or their associated accessories. Therefore, light and compact structural designs are highly significant for electric vehicles. Lightweight structures are also important for long-range EVs because they increase energy-consumption efficiency and decrease the required battery capacity. Consequently, many modern automotive manufacturers have reduced the weights of vehicles by replacing some metal-based parts with parts made using fiber-reinforced 1 Department of Mechanical Engineering, Faculty of Engineering, King Mongkut’s University of Technology, Thonburi, Bangkok, Thailand 2 Advanced Materials and Structure Laboratory (AMASS) and Center for Lightweight Materials, Design, and Manufacturing, Department of Mechanical Engineering, Faculty of Engineering, King Mongkut’s University of Technology, Thonburi, Bangkok, Thailand 3 Mobility and Vehicle Technology Research Center (MOVE), King Mongkut’s University of Technology, Thonburi, Bangkok, Thailand Corresponding author: Sontipee Aimmanee, Advanced Materials and Structures Laboratory (AMASS) and Center for Lightweight Materials, Design, and Manufacturing, Department of Mechanical Engineering, Faculty of Engineering, King Mongkut’s University of Technology, Thonburi, 126 Prachauthit Rd., Bangmod, Thung-Khru 10140, Bangkok, Thailand. Email: sontipee.aim@kmutt.ac.th Proc IMechE Part C: J Mechanical Engineering Science 0(0) 1–18 ! IMechE 2020 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/0954406220917690 journals.sagepub.com/home/pic