This paper studied the effect of backrest support (no backrest support (NBS), ergonomic backrest support (EBS) and non-ergonomic backrest support (N-EBS)) on the biodynamics of the head-cervical spine. Using a previously developed finite element model of a 3D body-seat system, modal and random response analyses were done under vertical white noise excitation (between 0 and 20 Hz at 1 m/s2 r.m.s). The results showed that modal frequencies at 5.45 and 7.33 Hz (EBS), 4.23 and 6.05 Hz (N-EBS) and 4.14 and 4.84 Hz (NBS) significantly influenced the vertical vibration of the seated human body. Compared to the NBS model, the peak frequencies of the head and neck response increased by 33% and 55% in the N-EBS and EBS models, respectively, and peak amplitudes at the front of the head increased by 25% (N-EBS) and 45% (EBS), while those at the back of the head-cervical spine decreased consistently. The response of the different positions of the head varied most significantly in the EBS model, with peak frequency and difference of 53% and 30%, respectively. All back supports showed the highest stress at C5–C6 of the cervical disc, with a peak between 1 and 2 Hz. Notably, EBS reduced the vertical cervical response but increased the anterior-posterior response. This paper provided a new idea for studying the biodynamics of the head-cervical spine as well as theoretical and applied guide for the safe and comfortable design of seats and the reduction of cervical spine injuries.
LiangCCChiangCF. Modeling of a seated human body exposed to vertical vibrations in various automotive postures. Ind Health2008; 46(2): 125–137.
2.
ZhengGQiuYGriffinMJ. Vertical and dual-axis vibration of the seated human body: nonlinearity, cross-axis coupling, and associations between resonances in transmissibility and apparent mass. J Sound Vib2012; 331(26): 5880–5894.
3.
DongR-CHeLDuW, et al. Effect of sitting posture and seat on biodynamic responses of internal human body simulated by finite element modeling of body-seat system. J Sound Vib2019; 438: 543–554.
4.
KuangHQiuYLiuC, et al. A nonlinear biodynamic model of seated human body exposed to vertical vibration with sensitivity analysis. Mech Syst Signal Process2023; 204: 110758.
5.
MirakhorloMKluftNShyrokauB, et al. Effects of seat back height and posture on 3D vibration transmission to pelvis, trunk and head. Int J Ind Ergon2022; 91: 103327.
6.
LiuCQiuYGriffinMJ. Finite element modelling of human-seat interactions: vertical in-line and fore-and-aft cross-axis apparent mass when sitting on a rigid seat without backrest and exposed to vertical vibration. Ergonomics2015; 58(7): 1207–1219.
7.
KimEFardMKatoK. A seated human model for predicting the coupled human-seat transmissibility exposed to fore-aft whole-body vibration. Appl Ergon2020; 84: 102929.
8.
BasriBGriffinMJ. The application of SEAT values for predicting how compliant seats with backrests influence vibration discomfort. Appl Ergon2014; 45(6): 1461–1474.
9.
NawaysehN. Effect of the seating condition on the transmission of vibration through the seat pan and backrest. Int J Ind Ergon2015; 45: 82–90.
10.
ZhangXQiuYGriffinMJ. Transmission of vertical vibration through a seat: effect of thickness of foam cushions at the seat pan and the backrest. Int J Ind Ergon2015; 48: 36–45.
11.
WangWRakhejaSBoileauPÉ. Relationship between measured apparent mass and seat-to-head transmissibility responses of seated occupants exposed to vertical vibration. J Sound Vib2008; 314(3): 907–922.
12.
MansfieldNJMaedaS. The apparent mass of the seated human exposed to single-axis and multi-axis whole-body vibration. J Biomech2007; 40(11): 2543–2551.
13.
MandapuramSRakhejaSBoileauP-É, et al. Apparent mass and head vibration transmission responses of seated body to three translational axis vibration. Int J Ind Ergon2012; 42(3): 268–277.
14.
RakhejaSDongRGPatraS, et al. Biodynamics of the human body under whole-body vibration: synthesis of the reported data. Int J Ind Ergon2010; 40(6): 710–732.
15.
HinzBSeidelH. The nonlinearity of the human body’s dynamic response during sinusoidal whole body vibration. Ind Health1987; 25(4): 169–181.
16.
HolmlundPLundströmRLindbergL. Mechanical impedance of the human body in vertical direction. Appl Ergon2000; 31(4): 415–422.
17.
QiuYGriffinMJ. Biodynamic responses of the seated human body to single-axis and dual-axis vibration. Ind Health2010; 48(5): 615–627.
18.
ZhangXQiuYGriffinMJ. Developing a simplified finite element model of a car seat with occupant for predicting vibration transmissibility in the vertical direction. Ergonomics2015; 58(7): 1220–1231.
19.
SeidelH. On the relationship between whole-body vibration exposure and spinal health risk. Ind Health2005; 43(3): 361–377.
20.
Van DrunenPVan Der HelmFCVan DieënJH, et al. Trunk stabilization during sagittal pelvic tilt: from trunk-on-pelvis to trunk-in-space due to vestibular and visual feedback. J Neurophysiol2016; 115(3): 1381–1388.
21.
ForbesPADe BruijnESchoutenAC, et al. Dependency of human neck reflex responses on the bandwidth of pseudorandom anterior-posterior torso perturbations. Exp Brain Res2013; 226(1): 1–14.
22.
LiuYDongRLiuZ, et al. Finite element analysis of the cervical spine: dynamic characteristics and material property sensitivity study. Comput Methods Biomech Biomed Eng2025; 28: 893–907.
23.
DongRTangSChengX, et al. Influence of foot excitation and shin posture on the vibration behavior of the entire spine inside a seated human body. Comput Methods Biomech Biomed Eng2024; 27: 1664–1679.
24.
YuSDongRCLiuZ, et al. Impact of sacroiliac interosseous ligament tension and laxity on the biomechanics of the lumbar spine: a finite element study. World Neurosurg2024; 185: e431–e441.
25.
ZhuSDongRLiuZ, et al. A finite element method study of the effect of vibration on the dynamic biomechanical response of the lumbar spine. Clin Biomech2024; 111: 106164.
26.
DongRZhuSChengX, et al. Study on the biodynamic characteristics and internal vibration behaviors of a seated human body under biomechanical characteristics. Biomech Model Mechanobiol2024; 23: 1449–1468.
27.
GrujicicMPanduranganBArakereG, et al. Seat-cushion and soft-tissue material modeling and a finite element investigation of the seating comfort for passenger-vehicle occupants. Mater Des2009; 30(10): 4273–4285.
28.
HendriksFMBrokkenDVan EemerenJT, et al. A numerical-experimental method to characterize the non-linear mechanical behaviour of human skin. Skin Res Technol2003; 9(3): 274–283.
29.
DuXRenJSangC, et al. Simulation of the interaction between driver and seat. Chin J Mech Eng2013; 26(6): 1234–1242.
30.
WheeldonJAStemperBDYoganandanN, et al. Validation of a finite element model of the young normal lower cervical spine. Ann Biomed Eng2008; 36(9): 1458–1469.
31.
LeeSHImYJKimKT, et al. Comparison of cervical spine biomechanics after fixed- and mobile-core artificial disc replacement: a finite element analysis. Spine (Phila Pa 1976)2011; 36(9): 700–708.
32.
LinGWangZGuoL, et al. Development and validation of cervical spine finite element model. J Clin Neurosurg2011; 8: 169–172.
33.
KallemeynNGandhiAKodeS, et al. Validation of a C2–C7 cervical spine finite element model using specimen-specific flexibility data. Med Eng Phys2010; 32(5): 482–489.
34.
KongWZGoelVK. Ability of the finite element models to predict response of the human spine to sinusoidal vertical vibration. Spine (Phila Pa 1976)2003; 28(17): 1961–1967.
35.
SangDDuC-FWuB, et al. The effect of cervical intervertebral disc degeneration on the motion path of instantaneous center of rotation at degenerated and adjacent segments: a finite element analysis. Comput Biol Med2021; 134: 104426.
36.
DuCMoZTianS, et al. Biomechanical investigation of thoracolumbar spine in different postures during ejection using a combined finite element and multi-body approach. Int J Numer Method Biomed Eng2014; 30(11): 1121–1131.
37.
MeyerFWillingerRLegallF. The importance of modal validation for biomechanical models, demonstrated by application to the cervical spine. Finite Elem Anal Des2004; 40(13): 1835–1855.
38.
MeyerFBourdetNWillingerR, et al. Finite element modelling of the human head-neck: modal analysis and validation in the frequency domain. Int J Crashworthiness2004; 9(5): 535–545.
39.
Hong-WanNEe-ChonTQing-HangZ. Biomechanical effects of C2-C7 intersegmental stability due to laminectomy with unilateral and bilateral facetectomy. Spine (Phila Pa 1976)2004; 29(16): 1737–1745.
40.
SunZLuTLiJ, et al. A finite element study on the effects of follower load on the continuous biomechanical responses of subaxial cervical spine. Comput Biol Med2022; 145: 105475.
41.
WheeldonJAPintarFAKnowlesS, et al. Experimental flexion/extension data corridors for validation of finite element models of the young, normal cervical spine. J Biomech2006; 39(2): 375–380.
42.
PanjabiMMCriscoJJVasavadaA, et al. Mechanical properties of the human cervical spine as shown by three-dimensional load-displacement curves. Spine (Phila Pa 1976)2001; 26(24): 2692–2700.
43.
YoganandanNStemperBDPintarFA, et al. Normative segment-specific axial and coronal angulation corridors of subaxial cervical column in axial rotation. Spine (Phila Pa 1976)2008; 33(5): 490–496.
44.
YoganandanNPintarFAStemperBD, et al. Level-dependent coronal and axial moment-rotation corridors of degeneration-free cervical spines in lateral flexion. J Bone Joint Surg Am2007; 89(5): 1066–1074.
45.
PaddanGSGriffinMJ. The transmission of translational seat vibration to the head—I. Vertical seat vibration. J Biomech1988; 21(3): 191–197.
46.
WeiLGriffinMJ. Mathematical models for the apparent mass of the seated human body exposed to vertical vibration. J Sound Vib1998; 212(5): 855–874.
47.
LuZDongRLiuZ, et al. Influence of muscle soft tissue and lower limbs on the vibration behavior of the entire spine inside the seated human body: a finite element study. Proc IMechE, Part H: J Engineering in Medicine2024; 238(7): 731–740.
48.
GaoKLiCXiaoY, et al. Finite element modeling and parameter identification of the seated human body exposed to vertical vibration. Biomech Model Mechanobiol2021; 20(5): 1789–1803.
49.
BhiwapurkarMKSaranVHHarshaSP. Seat to head transmissibility during exposure to vertical seat vibration: effects of posture and vibration magnitude. Int J Acoust Vib2019; 24: 3–11.
50.
HinzBMenzelGBlüthnerR, et al. Seat-to-head transfer function of seated men—determination with single and three axis excitations at different magnitudes. Ind Health2010; 48: 565–583.
51.
LiJHuangY. The effects of the duration on the subjective discomfort of a rigid seat and a cushioned automobile seat. Int J Ind Ergon2020; 79: 103007.
52.
BhiwapurkarMKSaranVHHarshaSP. Effects of posture and vibration magnitude on seat to head transmissibility during exposure to fore-and-aft vibration. J Low Freq Noise Vib Active Control2018; 38(2): 826–838.
53.
MandapuramSRakhejaSMarcotteP, et al. Analyses of biodynamic responses of seated occupants to uncorrelated fore-aft and vertical whole-body vibration. J Sound Vib2011; 330(16): 4064–4079.
54.
KitazakiSGriffinMJ. A modal analysis of whole-body vertical vibration, using a finite element model of the human body. J Sound Vib1997; 200(1): 83–103.
55.
BellKMYanYHartmanRA, et al. Influence of follower load application on moment-rotation parameters and intradiscal pressure in the cervical spine. J Biomech2018; 76: 167–172.
56.
CaiX-YYuchiC-XDuC-F, et al. The effect of follower load on the range of motion, facet joint force, and intradiscal pressure of the cervical spine: a finite element study. Med Biol Eng Comput2020; 58(8): 1695–1705.
57.
WangWRakhejaSBoileauP-É. Effect of back support condition on seat to head transmissibilities of seated occupants under vertical vibration. J Low Freq Noise Vib Active Control2006; 25: 239–259.
58.
TaoSGuihongXLingjingC. A study on the road model with four-wheel non-stationary random excitations. Automot Eng2013; 35(10): 868–872.
59.
LiFLiXShangD, et al. Structural optimization and dynamic analysis of vehicle suspension seat coupling system. In: Proceedings of the 2020 international symposium on autonomous systems (ISAS), Guangzhou, China, 6–8 December 2020.
60.
ZhangJLChenRFYaoK. Analysis on influence of road pavement roughness on vehicle vibration. J Highway Transp Res Dev2019; 36(11): 129–133.
61.
DongRGWelcomeDEMcdowellTW, et al. Theoretical foundation, methods, and criteria for calibrating human vibration models using frequency response functions. J Sound Vib2015; 356: 195–216.
62.
MattosGAMcintoshASGrzebietaRH, et al. Sensitivity of head and cervical spine injury measures to impact factors relevant to rollover crashes. Traffic Inj Prev2015; 16 Suppl1: S140–S147.
63.
Jimenez MartinezM. Artificial neural networks for passive safety assessment. Eng Lett2022; 30: 289–297.
