The Transverse Response of the Lumbar Spine under Longitudinal Loads
Abstract
A novel continuous model of the spine is presented. The transverse motion in the sagittal plane of the spine of sitting human subjects exposed to vertical vibrations revealed considerable bending along the lumbar spine and negligible bending along the thoracic spine. Therefore, the model consists of a curved rod, representing the lumbar spine, longitudinally loaded by a mass, representing the thorax. The differential equation of the transverse motion was derived and solved by making a product assumption. No transverse displacements and no bending moment was assumed at the pelvic end. At the thoracic end, a shear force and a bending moment are applied, representing translatory and rotatory inertia of the attached rib cage. Eigenfunctions and eigenvalues depend on longitudinal loading. The eigenfunctions correlate well with data obtained over a large range of experimental conditions. The solution for the time distribution contains various distinct harmonic components if an external force, alternating sinusoidally at only one discrete frequency, is applied. This effect is due to a periodic parameter in the differential equation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1971
- Accession Number
- AD0740461
Entities
People
- H. E. Krause
- Mahmoud Shirazi
Organizations
- Air Force Research Laboratory