Research on residual stress field control mechanism of circular saw blade considering its body structure

In this paper, 3D roll tensioning elastoplastic model was built by finite element method and the research object was a common circular saw blade body with hole, slot, and scraper structure. The theoretical calculation results show that there are areas dominated by tangential compressive stress near slot and scraper of roll tensioned saw blade body, which is not the expected result. It is proved that residual stress of saw blade body can be regulated by combining roll tensioning and local plastic compression process in this paper. The theoretical calculation results show that the outer edge of saw blade body near slot and scraper becomes area dominated by tangential tensile stress after the improved tensioning process. The improved tensioning process has little effect on stiffness and waist strength of circular saw blade.

Pressure welding of shells under creep-plastic compression

A calculation scheme for pressure welding of shells is proposed. Analytical expressions are obtained for the material in the states of plasticity, creep and creep-plasticity during pressure welding. Keywords: pressure welding, plasticity, creep, time, relaxation. [email protected], [email protected]

ABOUT THE FEATURES OF THE PROCESS OF CIRCULAR PLASTIC COMPRESSION STRANDS

A simulation of the process of circular plastic compression of a strand of construction 1+6 by stretching in four pairs of rollers is carried out. It is established that the wires of the outer layer of the strand swell before entering the first pair of rollers, as well as selective formation of local areas of sharply increased plastic deformation on the outer surface of the wires.

Device for plastic compression of long-dimensional cylindrical samples in linear stress conditions

A design of the device for studying plastic compression of long cylindrical specimens under conditions of a linear stress state is presented. The device is developed to study the properties of metals under plastic deformation in conditions of nonmonotonic loading. The goal of getting the accurate experimental data entails the necessary of carrying out tests using one long-length cylindrical sample, with the calculated length being more than five diameters. To prevent flexure of the long-length sample upon compression, the support conical sectors made by cutting truncated cone shaped blank into 6 or 8 equal parts with a central longitudinal hole having a diameter equal to the diameter of the test sample are used. The sectors are coupled by two pairs of semirings. A transcendental equation is obtained for determination of the taper angle of those sectors on the basis of kinematic analysis of the mobile links. This angle depends on the total weight of the sectors and sliding friction coefficients in the corresponding kinematic pairs of the device. For the considered device, the taper angle of the sectors is 36°. This device is designed and manufactured for compression testing of the samples with a diameter of 16.5 mm and a gaged length of 135 mm. Samples from steel 45 are tested with a goal of the flow curve construction and experimental verification of the strain diagrams under conditions of cyclic tensile-compression. Comparison of the calculated and experimental data proved the satisfactory accuracy of the stress determination, which makes it possible to recommend this device as a testing tool to be used in mechanical laboratories of the universities and research institutes.

Injectable Hydrogel versus Plastically Compressed Collagen Scaffold for Central Nervous System Applications

Central Nervous System (CNS) repair has been a challenge, due to limited CNS tissue regenerative capacity. The emerging tools that neural engineering has to offer have opened new pathways towards the discovery of novel therapeutic approaches for CNS disorders. Collagen has been a preferable material for neural tissue engineering due to its similarity to the extracellular matrix, its biocompatibility, and antigenicity. The aim was to compare properties of a plastically compressed collagen hydrogel with the ones of a promising collagen-genipin injectable hydrogel and a collagen-only hydrogel for clinical CNS therapy applications. The focus was demonstrating the effects of genipin cross-linking versus plastic compression methodology on a collagen hydrogel and the impact of each method on clinical translatability. The results showed that injectable collagen-genipin hydrogel is better clinical translation material. Full collagen compression seemed to form extremely stiff hydrogels (up to about 2300 kPa) so, according to our findings, a compression level of up to 75% should be considered for CNS applications, being in line with CNS stiffness. Taking that into consideration, partially compressed collagen 3D hydrogel systems may be a good tunable way to mimic the natural hierarchical model of the human body, potentially facilitating neural repair application.