Vol.:(0123456789) 1 3 Journal of Vibration Engineering & Technologies https://doi.org/10.1007/s42417-020-00254-x ORIGINAL PAPER An Improved Biomechanical Model to Optimize Biodynamic Responses Under Vibrating Medium Veeresalingam Guruguntla 1  · Mohit Lal 1 Received: 22 May 2020 / Revised: 30 September 2020 / Accepted: 1 October 2020 © Krishtel eMaging Solutions Private Limited 2020 Abstract Purpose The vibration is a mechanical phenomenon created by man or machine. Persons involved in on/of-road vehicle driving expose to intense vibrations and shocks owing to uneven and asymmetrical terrains. The prolonged vibration exposure may lead to musculoskeletal disorders followed by injuries. To examine human body movements and biodynamic responses precisely, it is obligatory to establish a reliable biomechanical model. Objective To do so, the present paper proposes a ten degrees-of-freedom (dofs) biomechanical model of the seated human. Methods The novelty of the proposed model is that it hypothetically divides the real human structure into segments as a head, thorax, abdomen, pelvis, left upper arm, left forearm, left hand, right upper arm, right forearm, and right hand, respectively, which are mainly missing in the human model developed in past. The mechanical parameters are utilized to defne the biomechanical model and optimized through the frefy algorithm. After optimization, the biodynamic responses: seat to head transmissibility, apparent mass and driving point mechanical impedance are calculated for the proposed model and compared with Allen 2-dofs model, Wan and Schimmels 4-dofs model, Bai et al. 4-dofs model, Darling et al. 7-dofs model and Boileau et al. experimental . Results and Conclusion The overall goodness of ft is compared for the proposed model with fve other models and found that the proposed model gives maximum goodness of ft (93.47). Also, the sensitivity analysis (± 10% variation in mass, stifness and damping) is performed to validate the reliability of the developed model. And, it is observed that the mass, stifness, and damping of the pelvis region have a signifcant role in peak modulus of biodynamic responses. Keywords Human body modeling · Whole body vibration · Biodynamic responses · Firefy algorithm · Optimization · Experimental verifcation · Sensitivity analysis Introduction The human body is part of the physical world that is highly sophisticated and has a multifaceted structure, the charac- teristics of which vary from individual to individual and situation to situation. The interaction of human beings with various tools while performing diferent activities such as drilling, farming, skiing, construction, etc. leads to discomfort due to vibration [1]. The experimental studies [2–7] evidenced that human beings possibly injure or feel discomfort due to vibration. A strong association between human discomfort in diferent work activities (reading, writ- ing, drinking, and sketching), injury (low back pain, neck injury), and problems associated with muscle and fatigue with vibration is noticed [2–9]. In the past, the human dynamic properties are being calculated with the help of live humans and cadavers. An experiment on the live human being, under whole-body vibration (WBV), is performed to obtain a human response and compared with the response obtained from the biody- namic model [10]. The transmissibility ratio (TR) on seated occupant calculated experimentally is compared with TR obtained for diferent biodynamic models (2-dofs, 4-dofs, 7-dofs and 11-dofs) and claimed that experimental results match well with 4-dofs model [11]. Similar work as [11] is performed for standing occupants with diferent knee angles [12]. * Mohit Lal lalm@nitrkl.ac.in; dr.mohitlal@gmail.com Veeresalingam Guruguntla 518id1001@nitrkl.ac.in 1 Department of Industrial Design, National Institute of Technology Rourkela, Rourkela, Odisha 769008, India