0


RESEARCH PAPERS

J Biomech Eng. 1987;109(2):103-109. doi:10.1115/1.3138650.

The use of the resistive pulse technique for the measurement of microsphere and red cell transit times through single-pore “Nuclepore” membranes (with pore diameters of 3.5 to 7.0 μm and pore length of approximately 11 μm) is described. The investigation of the fluid mechanics and electrical characteristics of the experimental system provides methods for the determination of particle and cell size, and entrance and transit times. Experimental measurement of the position dependent velocity of spherical particles through the pore shows close agreement with theoretical models. Red cell size and transit time through different sized pores at physiological shear stresses is also measured.

Commentary by Dr. Valentin Fuster
J Biomech Eng. 1987;109(2):110-114. doi:10.1115/1.3138651.

The states of penile erection have not been quantified to establish their relationship to intracorporal fluid pressure and to soft tissue constraint. Computer-based circumferential rigidity sensing during erectile cycles now permits circumferential size and rigidity characterization. Measurements during dynamic infusion cavernometry and cavernosography relate intracorporal pressure and axial rigidity to circumference and circumferential rigidity characterization. Tumescence/rigidity coupling and tissue elastic contributions are identified from the combined data.

Commentary by Dr. Valentin Fuster
J Biomech Eng. 1987;109(2):115-120. doi:10.1115/1.3138652.

A pseudostrain-energy function is proposed for describing the behavior of excised sheets of canine visceral pleura. Pseudoelastic material constants are determined from experimental biaxial data by employing a nonlinear least-squares algorithm. The agreement between theory and experiment is shown to be quite good. Furthermore, the visceral pleura studied appears to be inelastic and to exhibit in-plane isotropy. Comparison with previous works is discussed.

Topics: Algorithms , Isotropy
Commentary by Dr. Valentin Fuster
J Biomech Eng. 1987;109(2):121-125. doi:10.1115/1.3138653.

The effect of opening shock of a chest-mounted reserve parachute on the head/neck dynamics is studied. Comparisons are made with similar effects of a back-mounted reserve parachute. The analysis employs a biodynamic computer model developed in earlier research. The results show that there are significant advantages of a chest-mounted over a back-mounted reserve parachute.

Commentary by Dr. Valentin Fuster
J Biomech Eng. 1987;109(2):126-131. doi:10.1115/1.3138654.

The mechanics of the lung parenchyma is studied using models comprised of line members interconnected to form 3-D cellular structures. The mechanical properties are represented as elastic constants of a continuum. These are determined by perturbing each individual cell from a reference state by an increment in stress which is superimposed upon the uniform stretching forces initially present in the members due to the transpulmonary pressure. A force balance on the distorted structure, together with a force-deformation law for the members, leads to a calculation of the strain increments of the members. Predictions based on the analysis of the 3-D isotropic dodecahedron are in good agreement with experimental values for the Young’s, shear, and bulk moduli reported in the literature. The model provides an explanation for the dependence of the elastic moduli on transpulmonary pressure, the geometrical details of the structure, and the stress-strain law of the tissue.

Commentary by Dr. Valentin Fuster
J Biomech Eng. 1987;109(2):132-138. doi:10.1115/1.3138655.

This paper presents the findings of a study conducted to determine peak forces generated in the human spine while the individual is engaged in lifting maximum acceptable weight. Calculations of forces and moments, acting on each body segment, were based on film data collected on four individuals for twelve variations of the manual lifting task. The variations were defined by: (i) box-size (three different boxes were used), (ii) presence or absence of handles, and (iii) symmetry and asymmetry of the lifting task (sagittal and nonsagittal lifting). In general, lower loads were accepted for lift when lifting asymmetrically or when lifting boxes without handles or when lifting bigger boxes. However, peak forces (compressive and shear forces in the spine and ground reaction forces) for these situations were not always lower than those generated when handling either compact boxes or boxes with handles or when lifting boxes symmetrically in the sagittal plane. On the basis of these results, it was concluded that lifting loads asymmetrically or in boxes without handles or in bulky boxes is relatively much more stressful than lifting the same load symmetrically or in boxes with handles or in compact boxes.

Commentary by Dr. Valentin Fuster
J Biomech Eng. 1987;109(2):139-147. doi:10.1115/1.3138656.

The fluid dynamic behavior of a Newtonian water/glycerol solution, a non-Newtonian polymer (separan) solution, and bovine blood were compared in the Penn State Electrical Ventricular Assist Device (EVAD). Pulsed doppler ultrasound velocimetry was used to measure velocities in the near wall region (0.95–2.7 mm) along the perimeter of the pump. Mean velocity, turbulence intensity, local and convective acceleration, and shear rate were calculated from the PDU velocity measurements. Flow visualization provided qualitative information about the general flow patterns in the EVAD. Results indicate that water/glycerol does not accurately model the flow characteristics of bovine blood in the EVAD. The non-Newtonian separan solution produced results closer to those of the bovine blood than did the water/glycerol solution. Near wall velocity magnitudes for the separan were similar to those of the bovine blood, but the profile shapes differed for portions of the pump cycle. All three fluids exhibited periods of stagnation. Bovine blood results indicated the presence of a desired rotational washout pattern at mid-systole, while results with the other fluids did not show this feature.

Commentary by Dr. Valentin Fuster
J Biomech Eng. 1987;109(2):148-153. doi:10.1115/1.3138657.

This paper is concerned with the modeling of the human body as a spring mass system. Based on certain assumptions, an analysis for evaluating the mass and stiffness values of the model is developed. As an illustration of the modeling procedure, a 15-degree-of-freedom model of a male body is considered. The computed natural frequencies of the model are found to be within the range of available experimental values.

Topics: Modeling , Springs , Stiffness
Commentary by Dr. Valentin Fuster
J Biomech Eng. 1987;109(2):154-159. doi:10.1115/1.3138658.

The flow energy loss (head loss) through a cast of canine central airways is found to be nearly independent of flow direction. By contrast, head loss in geometrically-simpler branching sections at comparable flow conditions is highly irreversible, with inspiratory loss being greater by nearly two units of dynamic pressure (2•1/2ρV2 ). In these branching sections head loss appears to be independent of important geometric parameters such as the branch length/diameter ratio and the exit/inlet flow-area ratio. An analysis of these observations suggests that kinetic energy factors, not shear stresses, account for most of the energy dissipated in central airways and in simple bifurcating sections. Inspiratory loss in bifurcations is greatly increased by the onset of flow separation: irreversibility is minimal in central airways, where separation either is absent or else is much less pronounced.

Commentary by Dr. Valentin Fuster
J Biomech Eng. 1987;109(2):160-162. doi:10.1115/1.3138659.

The pressure-volume relationship of lungs subjected to repeated compression and expansion is studied in detail. The investigation was motivated by an attempt to understand why lungs are frequently injured by compression waves; hence the lung was compressed to a degree greater than normally encountered in physiological conditions. Attention was focused on the collapse of the lung at a critical strain and the reopening of the trap at a critical stress. We found that when a rabbit lung is compressed, about one-half to one-quarter of its gas may be trapped in the alveoli because of the closure of airways. Reopening of the trap occurs at a pressure higher than the critical pressure for collapsing. The difference of the critical pressures of collapsing and reopening is influenced by the rate of strain and the strain history, especially by the maximum compressive stress imposed on the lung. The stress-strain relationship of the lung tissue, which resembles the PV curves, depends strongly on the strain history.

Commentary by Dr. Valentin Fuster
J Biomech Eng. 1987;109(2):163-168. doi:10.1115/1.3138660.

An efficient method for gross-motion simulation of head/neck dynamics in accidents and high acceleration environments is presented. The method uses finite-segment modelling to develop a 3-body model of the head/neck system. The model is shown to compare favorably with an analogous 9-body model and with experimental data. The model is expected to be useful for: (1) efficient analysis of gross-motion head/neck dynamics during accidents; (2) for developing increased intuitive understanding of head/neck behavior; and (3) for use with gross-motion, whole-body, crash-victim simulators.

Commentary by Dr. Valentin Fuster
J Biomech Eng. 1987;109(2):169-174. doi:10.1115/1.3138661.

The mechanical properties of human lung tissue were measured in a state of biaxial tension. The experimental data were fitted with a pseudo-elastic constitutive equation proposed earlier and the physical constants were identified.

Commentary by Dr. Valentin Fuster

TECHNICAL BRIEFS

Commentary by Dr. Valentin Fuster

BOOK REVIEWS

J Biomech Eng. 1987;109(2):177. doi:10.1115/1.3138663.
FREE TO VIEW
Abstract
Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster
J Biomech Eng. 1987;109(2):178. doi:10.1115/1.3138665.
FREE TO VIEW
Abstract
Topics: Aerodynamics , Design
Commentary by Dr. Valentin Fuster
J Biomech Eng. 1987;109(2):179. doi:10.1115/1.3138666.
FREE TO VIEW
Abstract
Commentary by Dr. Valentin Fuster

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In