Abstract—Cab’s frame strength is considered as an important factor in excavator’s operator safety, especially during roll-over. In this study, we use a model of cab frame with different thicknesses and perform elastoplastic numerical analysis by using Finite Element Method (FEM). Deformation mode and energy absorption’s of cab’s frame part are investigated on two conditions, with wrinkle and without wrinkle. The occurrence of wrinkle when deforming cab frame can reduce energy absorption, and among 4 parts with wrinkle, the energy absorption significantly decreases in part C. Residual stress that generated upon the bending process of part C is analyzed to confirm it possibility in increasing the energy absorption. Keywords—ROPS, FEM, hydraulic excavator, cab frame, energy absorption. I.INTRODUCTION ECENTLY, construction machines have been commonly provided with a cab structure that is configured to protect an operator when the machines fall down. Hydraulic excavator scaffolds may use in unstable land or slopes, with a tipped over or roll over risk. Roll-Over Protective Structure (ROPS) standards have been established and considered as an important factor to protect occupant when hydraulic excavator falls. Operator's seat must be secured to passenger space in cab frame. It is necessary to withstand impact because of fall with increasing frame strength [1]-[5]. Cab frame of hydraulic excavator which was intended to isolate the occupants from wind and rain, will crushed upon fall, and this may be dangerous to passenger. The danger comes from the impact energy that transmitted to the excavator occupant. To increase passenger safety, the impact energy transmitted should be as low as possible. To minimize the impact energy, it is necessary to dissipate the energy that comes because of tipped over or rolled over by absorbing the energy through deformation of excavator structure. To increase cab frame strength, the structural change by adding the thickness and material change has been done. Nevertheless, then, the production cost of cab frame will increase. The necessity to perform analysis during development to reduce development period and cost are discussed [6]. In this study, we use a model of cab frame with varying thickness and Shigeyuki Haruyama and Ken Kaminishi are with graduate School of Innovation & Technology Management, Yamaguchi University, Ube, Japan (e-mail: haruyama@yamaguchi-u.ac.jp, kaminisi@yamaguchi-u.ac.jp). Oke Oktavianty and Zefry Darmawan are with Department of Mechanical Engineering, Yamaguchi University, Japan and lecturer at Industrial Engineering Department, University of Brawijaya, Indonesia (e-mail: u504wc@yamaguchi-u.ac.jp, v501wc@yamaguchi-u.ac.jp). Tadayuki Kyoutani is with Graduate School of Science and Technology, Department of Mechanical Engineering, Yamaguchi University, Ube, Japan. we performed elastoplastic numerical analysis with FEM. While generating local wrinkle, a thin cylindrical tube that is mainly used as automotive body structure, can absorb energy [7]. Residual stresses are the stresses that remained in a solid material after the original cause of the stresses has been removed. Residual stresses can occur through a variety of mechanisms such as bending, welding etc. Residual stresses due to bending process is discussed and analyzed [8], [9]. In this study, wrinkle occurrence effect to energy absorption in deformation mode on each part is investigated. Effect of energy absorption characteristics by residual stress that generated upon bending process is discussed. II. ENERGY ABSORPTION CHARACTERISTIC A.Condition Analysis An elastoplastic numerical analysis of cab frame with general-purpose analysis software is performed by using MSC. Marc software. The analysis model is shown in Fig. 1. Fig. 1 Analysis model Analysis model is created by combining a cylindrical part of quadrilateral axisymmetric shell elements. The frame is classified into 11 parts namely A ~ K. The boundary condition of frame bottom surface in 4 corners is completely restrained as shown in Fig. 2. A rigid wall (116 mm × 900 mm) beside part D with forced displacement 500 mm is allowed to collapse the model. The material properties of cab frame are homogeneous and isotropic of elastic-plastic. Stress-strain relationship is Shigeyuki Haruyama, Oke Oktavianty, Zefry Darmawan, Tadayuki Kyoutani, Ken Kaminishi Study on Energy Absorption Characteristic of Cab Frame with FEM R World Academy of Science, Engineering and Technology International Journal of Mechanical and Mechatronics Engineering Vol:10, No:3, 2016 570 International Scholarly and Scientific Research & Innovation 10(3) 2016 scholar.waset.org/1307-6892/10003972 International Science Index, Mechanical and Mechatronics Engineering Vol:10, No:3, 2016 waset.org/Publication/10003972