Bio-Medical Materials and Engineering - Volume 1, issue 4

Authors: Tamaki, Tamotsu | Panjabi, Manohar M.

Article Type: Research Article

Abstract: Viscoelastic behavior of the functional spinal unit (FSU) under the application of moment is important for the biomechanical understanding of physiological and pathological aspects of spine. This paper presents a mechanical model on viscoelastic behavior of intervertebral disc connecting two vertebral bodies where a posterior element and surrounding tissues have been removed from FSU. The model, which is composed of a nonlinear spring and a linear Kelvin element in series, is proposed. Specimen of human lumbar intervertebral disc (L3-intervertebral disc-L4) are used for the experiment of the cyclic moment application of flexion, extension and lateral bending with constant loading rates. …Simulations by the proposed model are compared with the experiment. It is suggested that the model is good for the prediction of viscoelastic behavior of the intervertebral disc. Show more

Keywords: intervertebral disc, mechanical model, flexion, extension and lateral bending, viscoelasticity

DOI: 10.3233/BME-1991-1401

Citation: Bio-Medical Materials and Engineering, vol. 1, no. 4, pp. 203-214, 1991

Authors: Yahia, L. H. | Desrosiers, E. A. | Rivard, C. H.

Article Type: Research Article

Abstract: A system has been developed to study in vitro the effects of mechanical stimulation on the biomechanical properties of ligaments. The apparatus is based on a ball screw driven by a microcomputer-controlled stepper motor capable of generating 100 Newtons of traction, the resulting force in the tissue is monitored in real-time acquisition by a load cell. It is programmed to perform virtually any kind of mechanical stimulation or biomechanical characterization tests. Preliminary tests on canine anterior cruciate ligaments indicate that this system is adequate for a variety of mechanical stimulations and characterization assays.

Keywords: mechanical stimulation, biomechanics, ligaments, computer control, in vitro testing

DOI: 10.3233/BME-1991-1402

Citation: Bio-Medical Materials and Engineering, vol. 1, no. 4, pp. 215-222, 1991

Authors: Higo, Y. | Damri, D. | Nunomura, S. | Kumada, K. | Sawa, N. | Hanaoka, K. | Teranaka, T. | Iwamoto, T.

Article Type: Research Article

Abstract: A fracture mechanics approach has been adopted in the present study to investigate the fracture toughness behavior of three commercial composite resins for dental use named Clearfil photo posterior, P-50 and Occlusin. The resins have been cast in to ring-shaped specimens for the determination of individual fracture toughness values. The experimentally determined values have been compared with fracture toughness values obtained from the indentation micro-fracture method, which is the currently more popular test method for determining fracture toughness characteristics of composite resins. Occlusin was found to exhibit higher fracture toughness values than any other resin, employing the ring specimen test …procedure. However, this was not the case when using the indentation method which gave comparable fracture toughness values for all three resins. It was concluded that the ring specimen provides a simple, accurate and reproducible method for providing a measure of the materials fracture toughness. Show more

Keywords: fracture toughness, ring specimen, fatigue precracking, pop-in, crack arrest

DOI: 10.3233/BME-1991-1403

Citation: Bio-Medical Materials and Engineering, vol. 1, no. 4, pp. 223-231, 1991

Authors: Yokobori, Jr., A. Toshimitsu | Ohkuma, Tsuneo | Maeyama, Toshihide | Ohuchi, Hiroshi | Yokobori, Takeo

Article Type: Research Article

Abstract: The aim of this study is to elucidate the relation of the inelastic expansive deformation of natural blood vessel and the degradation of elasticity to the time pattern of circulating pulsatile pressure flow. When pulsatile pressure amplitude (ΔP = Pmax −Pmin ) becomes smaller due to Pmin increasing, the blood vessel is subject to creep deformation. In this sense, pulsating pressure will play a role in avoiding creep effect. Fluctuation of maximum pressure P max will induce the increase of inelastic deformation and the decrease of rigidity of the blood vessel. The inelastic deformation and the decrease of rigidity …in blood vessel is induced at the stage of pressure amplitude rising from a lower one to a higher, but not during pressure amplitude (ΔP) kept constant nor at the pressure amplitude decreasing stage. In order to reduce the degradation of mechanical properties of blood vessel, it may be effective to avoid the increase of Pmin and the variability of Pmax . Show more

Keywords: blood vessel, inelastic deformation, degradation, pulsatile pressure flow, creep

DOI: 10.3233/BME-1991-1404

Citation: Bio-Medical Materials and Engineering, vol. 1, no. 4, pp. 233-241, 1991

Authors: Tomita, Naohide | Kutsuna, Tatsuo | Tamai, Susumu | Ueda, Yurito | Ikeuchi, Ken | Ikada, Yoshito

Article Type: Research Article

Abstract: In vitro and in vivo experiments were carried out to study mechanical effects of the cushioned plate fixation in which a cushion was placed between a metal plate and bone. The cushioned plate fixation was found to be flexible in the physiological stress range and to reduce the stick slip between bone and the plate. A blood-soaked compression test indicated that the cushion moderates the stress shielding effect which occurs in the vicinity of the rigid plate, this being consistent with the result of in vivo experiments.

Keywords: fracture fixation plate, mechanical property, osteoporosis, cushioned plate, silicone rubber

DOI: 10.3233/BME-1991-1405

Citation: Bio-Medical Materials and Engineering, vol. 1, no. 4, pp. 243-250, 1991

Authors: Chauhan, S. K. | Singh, V. R.

Article Type: Research Article

Abstract: It is common practice in orthopaedic surgery to drill holes in bones for the placement of screws. Such holes make the bone weaker compared to an intact one. The loss of strength after drilling holes in the compact bone is studied here.

Keywords: loss of strength, drilled bone, orthopaedic surgery

DOI: 10.3233/BME-1991-1406

Citation: Bio-Medical Materials and Engineering, vol. 1, no. 4, pp. 251-253, 1991

Article Type: Other

Citation: Bio-Medical Materials and Engineering, vol. 1, no. 4, pp. 255-261, 1991