A biomechanical model of a vehicle passenger in the sagittal plane

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Abstract

Musculoskeletal biomechanical models have wide applications in ergonomics, rehabilitation, and injury estimation. Their use can be extended to enable quantitatively explaining and estimating ride comfort for a vehicle's passenger. A biomechanical model of the upper body in the sagittal plane is constructed, which allows for curved motion to simulate the propagation of disturbance energy within a seated passenger aboard a moving vehicle. The dynamic predictions of the model are validated against experimental results within the literature. Frequency responses show that within the vehicular frequency range, the L4L5 and the L5S1 discs in the lower lumbar region are susceptible to the highest vibration transmission. It was also found that vibration transmission is maximized at around 4.5 Hz. The model provides analytical and geometric intuition into the motion of the various segments of the upper body using a few simple geometric assumptions and can be employed to develop a quantitative ride-comfort metric, such that the most comfortable ride would be that which would induce the least internal motion within the passenger model.

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Most cited references 45

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New in vivo measurements of pressures in the intervertebral disc in daily life.

Hans-Joachim Wilke, Peter Neef, Marco Caimi … (1999)

We conducted intradiscal pressure measurements with one volunteer performing various activities normally found in daily life, sports, and spinal therapy. The goal of this study was to measure intradiscal pressure to complement earlier data from Nachemson with dynamic and long-term measurements over a broad range of activities. Loading of the spine still is not well understood. The most important in vivo data are from pioneering intradiscal pressure measurements recorded by Nachemson during the 1960s. Since that time, there have been few data to corroborate or dispute those findings. Under sterile surgical conditions, a pressure transducer with a diameter of 1.5 mm was implanted in the nucleus pulposus of a nondegenerated L4-L5 disc of a male volunteer 45-years-old and weighing 70 kg. Pressure was recorded with a telemetry system during a period of approximately 24 hours for various lying positions; sitting positions in a chair, in an armchair, and on a pezziball (ergonomic sitting ball); during sneezing, laughing, walking, jogging, stair climbing, load lifting during hydration over 7 hours of sleeping, and others. The following values and more were measured: lying prone, 0.1 MPa; lying laterally, 0.12 MPa; relaxed standing, 0.5 MPa; standing flexed forward, 1.1 MPa; sitting unsupported, 0.46 MPa; sitting with maximum flexion, 0.83 MPa; nonchalant sitting, 0.3 MPa; and lifting a 20-kg weight with round flexed back, 2.3 MPa; with flexed knees, 1.7 MPa; and close to the body, 1.1 MPa. During the night, pressure increased from 0.1 to 0.24 MPa. Good correlation was found with Nachemson's data during many exercises, with the exception of the comparison of standing and sitting or of the various lying positions. Notwithstanding the limitations related to the single-subject design of this study, these differences may be explained by the different transducers used. It can be cautiously concluded that the intradiscal pressure during sitting may in fact be less than that in erect standing, that muscle activity increases pressure, that constantly changing position is important to promote flow of fluid (nutrition) to the disc, and that many of the physiotherapy methods studied are valid, but a number of them should be re-evaluated.

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Lumbar disc disorders and low-back pain: socioeconomic factors and consequences.

Jeffrey Katz (2006)

Socioeconomic factors are important risk factors for lumbar pain and disability. The total costs of low-back pain in the United States exceed $100 billion per year. Two-thirds of these costs are indirect, due to lost wages and reduced productivity. Each year, the fewer than 5% of the patients who have an episode of low-back pain account for 75% of the total costs. Because indirect costs rely heavily on changes in work status, total costs are difficult to calculate for many women and students as well as elderly and disabled patients. These methodologic challenges notwithstanding, the toll of lumbar disc disorders is enormous, underscoring the critical importance of identifying strategies to prevent these disorders and their consequences.

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Is the nucleus pulposus a solid or a fluid? Mechanical behaviors of the nucleus pulposus of the human intervertebral disc.

Lori Setton, V C Mow, James Iatridis … (1996)

A new technique to measure the viscoelastic behavior of the nucleus pulposus in shear was used to assess its solid and fluid characteristics. To review existing knowledge on mechanical behaviors of the nucleus pulposus, and to develop a new technique to study the viscoelastic behaviors of isolated nucleus pulposus samples in torsional (pure) shear under transient and dynamic conditions. Numerous studies have investigated the swelling behavior of the nucleus and found the swelling pressure to range approximately 0.05-3 MPa, depending on loading conditions. Very few studies, however, have investigated the load-deformational behaviors of the nucleus pulposus. Thirteen nondegenerate samples of nucleus pulposus were harvested from lumbar discs and tested in torsional shear under transient and dynamic test conditions. A linear viscoelastic law with variable amplitude relaxation and dynamic frequency sweep experiments. The coefficients of the viscoelastic law were determined from the stress relaxation experiments, whereas the dynamic shear modulus and phase shift angle were determined from the frequency sweep. The nucleus exhibits significant viscoelastic effects in shear. Under transient conditions, the stress relaxed to values near zero, which is indicative of the "fluid-like" behaviors of the nucleus. Under dynamic conditions, however, the material parameters for the nucleus, magnitude of the complex modulus (7-21 kPa), and phase angle (23-31 degrees) were more characteristic of a viscoelastic solid. The authors' proposed stress-strain law exhibited excellent agreement with the viscoelastic data. In response to shear deformations, the nucleus pulposus exhibited significant viscoelastic effects, characteristic of a fluid and a solid. Whether the nucleus pulposus behaves more as a fluid or a solid in vivo depends on the rate of loading.

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Author and article information

Contributors

Ali Akbari

Donald Margolis

Journal

Journal ID (nlm-ta): Heliyon

Journal ID (iso-abbrev): Heliyon

Title: Heliyon

Publisher: Elsevier

ISSN (Electronic): 2405-8440

Publication date PMC-release: 16 February 2024

Publication date Collection: 29 February 2024

Publication date (Electronic): 16 February 2024

Volume: 10

Issue: 4

Electronic Location Identifier: e26375

Affiliations

[1]Department of Mechanical and Aerospace Engineering, UC Davis, CA, USA

Author notes

[∗ ]Corresponding author. alakbari@ 123456ucdavis.edu

Article

Publisher Item ID: S2405-8440(24)02406-X Publisher ID: e26375

DOI: 10.1016/j.heliyon.2024.e26375

PMC ID: 10884866

SO-VID: 8b64bfa9-8fa6-4812-8f48-7d8f3860eb9e

License:

This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).

History

Date received : 2 May 2023

Date revision received : 4 February 2024

Date accepted : 12 February 2024

A biomechanical model of a vehicle passenger in the sagittal plane

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Abstract

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Business Model Innovation in engineering

Most cited references 45

New in vivo measurements of pressures in the intervertebral disc in daily life.

Lumbar disc disorders and low-back pain: socioeconomic factors and consequences.

Is the nucleus pulposus a solid or a fluid? Mechanical behaviors of the nucleus pulposus of the human intervertebral disc.

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