Differences and correlations between the elastic characteristics of the compact bone tissue of the human tibia

Pair t tests have been carried out on experimental data indicating nonuniformity of the distribution of the elastic properties of the compact bone tissue over the cross section of the human tibia. The elastic characteristics obtained by nondestructive and destructive testing have been subjected to a linear correlation analysis. It is shown, with statistical reliability, that the compact bone tissue has a degree of anisotropy of the elastic properties higher than transverse isotropy.     

Effect of the size of the specimen cross section on the long-term strength of polyethylene

The scale effect has been investigated in relation to the long-term strength of specimens of high-density polyethylene. Time dependences of the tensile strength at ordinary temperatures have been obtained. It is shown that the long-term strength depends on the dimensions of the specimen cross section. The deformation of the specimens depends on their size and the shape of the gage cross section.Higher Chemical Technology Institute, Sofia. Translated from Mekhanika Polimerov, No. 4, pp. 741–743, July–August, 1973.     

The multipurpose optimal design of elastic structures with a piecewise uniform cross section

Zusammenfassun Die Arbeit beschäftigt sich mit dem optimalen Entwurf eines elastischen Tragwerks für mehrere Belastungszustände und vorgeschriebene Gesamtsteifigkeit. Frühere Ergebnisse werden verallgemeinert zwecks Aufstellung notwendiger und hinreichender Optimalitätsbedingungen für konvexe spezifische Kostenfunktionen. Eine Methode der optimalen Bemessung wird beschrieben und an Beispielen erläutert.

---

---

The research reported in this paper was supported by the Army Research Office (Durham) under Grant DA-ARO-D-31-124-G1025.     

Investigation of the nonunifcrmity of the acoustic properties of the human tibia

Mechanics of Composite Materials - A method is proposed for determining the propagation velocity and coefficient of attenuation of ultrasonic vibrations in both the whole diaphysis of the human...     

Scattering of a SH-wave by an elastic fiber of nonclassical cross section with an interface crack

The problem of interaction of a plane time-harmonic SH-wave with an elastic fiber of quasi-square or quasi-triangular cross section, when an interface crack is present between an infinite elastic matrix and the fiber, is considered. The modified null-field method taking into account the asymptotic behavior of the solution at crack tips is exploited for obtaining numerical results. The effects of fiber shape, fiber/matrix material combination, debonding (crack size), and direction of wave incidence on the scattering amplitude in the far zone are analyzed. Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 44, No. 2, pp. 245–254, March–April, 2008.     

Dependence of elastic and strength characteristics of high-modulus composites on schemes of reinforcement

The elastic and strength characteristics of high-modulus composites with 12 different reinforcement schemes have been studied thoroughly. The effect of reinforcement schemes on change in elastic and strength characteristics of composites has been evaluated. A calculation of the elastic characteristics of high-modulus composites has been performed from the properties of the reinforcement and binder, and a comparison of the results with experimental data is given. Diagrams of deformation upon extension of the composites studied are given.All-Union Scientific-Research Institute of Aviation Materials, Moscow. Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 6, pp. 1019–1027, November–December, 1974.     

Hardness of the human tibia

The hardness distribution over the compact bone tissue of the human tibia is examined along the length and in six different zones of the cross section of the bone. A correlation is established between the hardness numbers, on the one hand, and the characteristics of the mechanical properties and the biochemical composition of the bone tissue, on the other. The three-dimensional structure of the equal-hardness formations is studied. The results confirm the assumptions of [1] concerning the specific functions of each zone in the rheological adaptation of the bone to physiological loads.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga; Scientific Research Institute of Traumatology and Orthopedics, Riga. Translated from Mekhanika Polimerov, No. 6, pp. 1101–1107, November–December, 1973.     

Theoretical-experimental method for determining the averaged elastic and strength characteristics of a honeycomb core of sandwich designs

Analytic formulas for the averaged elastic and strength characteristics of a honeycomb core with a hexahedral structure are derived by introducing the hypothesis about the momentless work of its elements (walls) in the course of loading and during their stepwise exclusion from operation after their buckling in compression-compression or pure shear. The dimensionless coefficients appearing in the structural formulas when solving the problems formulated are to be determined from experimental data on tension, compression, and pure shear in two planes. It is shown that, in tension-compression, honeycomb must be considered as a heteromodular material with averaged elastoplastic properties, for which the relations between averaged stresses and averaged strains in compression and shear change stepwise on some sections (conditional plastic flow).     

Changes in the strength characteristics of human intervertebral disks under compression

Conclusions 1. The strength of intervertebral disks undergoes significant changes during the human lifetime. The data obtained allow the distinction of three periods: 1) a period of strength gain (newly born babies-18 years); 2) a stable period (20–40 years); and 3) a period of strength loss (from 50 to the death). The safety factor of strength of the intervertebral disks is the highest during the first two decades and decreases during the following age periods.2. The sex has a significant influence on the strength characteristics of the intervertebral disks.3. Changes in the limiting load of the intervertebral disks of the spine are characterized by a caudocranial gradient and the changes in the strength and the safety factor of strength, by a cranio-caudal gradient. The existing relationships do not depend on age or sex and reflect the significance of the functions of support and motion in different sections of the spinal column.4. The strength of the intervertebral disks depends on the degree of the degenerative-distrophic process, the mineral content of the tissues, the water content, and the ability of the disk tissues to retain water.S. V. Kurashov Kazan' State Medical Institute. Translated from Mekhanika Polimerov, No. 5, pp. 897–902, September–October, 1976.     

Anisotropy of the elastic and strength properties of reinforced plastics

The method and results of experimental investigation of anisotropy of the elastic and strength properties of reinforced plastics are discussed. A method of determining the mechanical characteristics in different directions on tubular test pieces is proposed. A special testing machine is described. It is shown that determining the strength and elastic properties of reinforced materials in directions other than the directions of reinforcing on flat test pieces cut mechanically leads to distorted results.Mekhanika Polimerov, Vol. 3, No. 3, pp. 461–466, 1967