A novel rat tail disc degeneration model induced by static bending and compression

Background:A new rat tail intervertebral disc degeneration model was established to observe the morphologic and biologic changes of static bending and compression applied to the discs.Methods:In total,20 Sprague-Dawley rats with similar weight were randomly di-vided into 4 groups.Group 1 served as a control group for a baseline assessment of normal discs.Group 2 underwent a sham surgery,using an external device to bend the vertebrae of coccygeal 8-10.Groups 3 and 4 were the loaded groups,and exter-nal devices were instrumented to bend the spine with a compression level of 1.8 N and 4.5 N,respectively.Magnetic resonance imaging(MRI),histological,and quanti-tative real-time PCR(qRT-PCR)analysis were performed on all animals on day 14 of the experiment.Results:Magnetic resonance imaging and histological results showed that the changes of intervertebral disc degeneration increased with the size of compression load.Some architecture disorganizations in nucleus pulposus and annulus fibro-sus were found on both of the convex and concave side in the groups of 1.8 N and 4.5 N.An upregulation of MM-3,MM-13,and collagen 1-α1 mRNA expression and a downregulation of collagen 2-α1 and aggrecan mRNA expression were observed in the sham and loading groups.Significant changes were found between the loading groups,whereas the sham group showed similar results to the control group.Conclusions:Static bending and compression could induce progressive disc degen-eration,which could be used for biologic study on disc degeneration promoted by static complex loading.

Haptic Evaluation of the Prickle of Fabrics: Axial Compression Bending Tests On Ramie Fibers

Although smoothness, softness, and stiffness determine the physical and mechanical behavior of a fabric and the subjective assessment of quality when it is handled, the perceived comfort of clothing is more important to consumers. The sensations perceived from the contact of clothing with the skin can greatly influence our over-all state of comfort and one aspect of this is the unpleasant skin sensation of prickle. Surface prickle of fabrics can be a factor limiting the use of the coarser types of ramie in apparel. And the mechanical stimulus of fabric-evoked prickle underlies our discomfort to fabrics independent in the majority of cases of any chemical or the atopic status of the individual. It is known that the prickle of fabric can be reduced by fabric-finishing treatments, but the assessment of fabric prickle is often done subjectively. This is time consuming, and it is difficult to obtain reliable and reproducible results, since variability between subjects in their sensitivity to prickle, such as skin mechanical properties, effective density of nociceptors and the mood state of the individual. In order to find an objective method of measuring the physical properties of the stiff fiber ends protruding from the fabrics to predict prickle, axial compression bending tests were examined by using single ramie fiber. By comparing analysis, it is found that the critical compressing load (Pcr), the bending modulus (E) are the important parameters. The relationship of the critical load (Pcr) with the length of fiber (L) and the fineness of fiber (Nt) has been investigated.

Performance enhancement of sandwich panels with honeycomb–corrugation hybrid core

The concept of combining metallic honeycomb with folded thin metallic sheets （corrugation） to construct a novel core type for lightweight sandwich structures is proposed. The honeycomb-corrugation hybrid core is manufactured by filling the interstices of aluminum corrugations with precision-cut trapezoidal aluminum honeycomb blocks, bonded together using epoxy glue. The performance of such hybrid-cored sandwich panels subjected to out-of-plane compression, transverse shear, and three-point bending is investigated, both experimentally and numerically. The strength and energy absorption of the sandwich are dramatically enhanced, compared to those of a sandwich with either empty corrugation or honeycomb core. The enhancement is induced by the beneficial interaction effects of honeycomb blocks and folded panels on improved buckling resistance as well as altered crushing modes at large plastic deformation. The present approach provides an effective method to further improve the mechanical properties of conventional honeycomb-cored sandwich constructions with low relative densities.

ELASTICITY SOLUTIONS OF SPHERICALLY ISOTROPIC CONES UNDER CONCENTRATED LOADS AT APEX

Based on the Ref [9]the displacement and stress distributions in a spherically isotropic cone subjected to concentrated loads at apex are studied The displacementand stresses are given explicitly for the cone in compression torsion and bending cases respectively based on the situation of the concentrated forces and moments Finally.the hollow cone problems are discussed .

Simulation of thermal stress in Er2O3 and Al2O3 tritium penetration barriers by finite-element analysis

The physical vapor deposition method is an effective way to deposit Al2O3 and Er2O3 on 316 L stainless steel substrates acting as tritium permeation barriers in a fusion reactor. The distribution of residual thermal stress is calculated both in Al2O3 and Er2O3 coating systems with planar and rough substrates using finite element analysis. The parameters influencing the thermal stress in the sputter process are analyzed, such as coating and substrate properties, temperature and Young＇s modulus. This work shows that the thermal stress in Al2O3 and Er2O3 coating systems exhibit a linear relationship with substrate thickness, temperature and Young＇s modulus.However, this relationship is inversed with coating thickness. In addition, the rough substrate surface can increase the thermal stress in the process of coating deposition. The adhesive strength between the coating and the substrate is evaluated by the shear stress. Due to the higher compressive shear stress, the Al2O3 coating has a better adhesive strength with a 316 L stainless steel substrate than the Er2O3 coating. Furthermore, the analysis shows that it is a useful way to improve adhesive strength with increasing interface roughness.

Preparation of FRC/Steel by Lap-joint and Its Mechanical Properties

The Lap-joint configuration and the vacuum assisted forming method were put forward to meet the demands of the compression bending strength and the strong connection between the steel and FRC.The bending mechanic tests of the Lap-joint bending specimens carried out, the fabricate processing stability, limit carrying capacity and failure modes were analyzed. The experimental results show that the fabricate processing of the Lap-joint is stable; the bending stiffness is 19.5 N/mm, and the limit bending moment reaches 318 N？m. The main failure modes are the failure of core material at junction of sandwich plate and steel, and the bending failure in the position of the inner and outer surface.