Search results for "BEARING"
showing 10 items of 284 documents
Effects of resistance training on lower-extremity impairments in older people with hip fracture
2008
Abstract Portegijs E, Kallinen M, Rantanen T, Heinonen A, Sihvonen S, Alen M, Kiviranta I, Sipila S. Effects of resistance training on lower-extremity impairments in older people with hip fracture. Objective To study the effects of resistance training on muscle strength parameters, mobility, and balance. Design Randomized controlled trial. Setting Research laboratory and senior gym. Participants Population-based sample of eligible 60- to 85-year-old community-dwelling men and women 0.5 to 7.0 years after hip fracture. Forty-six people had no contraindications and were willing to participate in the exercise trial. Intervention Twelve-week intensive progressive strength-power training (n=24),…
Locking plates for corrective osteotomy of malunited dorsally tilted distal radial fractures: a biomechanical study.
2005
The purpose of the study was to compare the biomechanical properties of five different palmar fixation plate designs in a distal radius osteotomy cadaver model. A 1 cm metaphyseal osteotomy gap was made to simulate a corrective osteotomy and the osteotomy plated. Axial load was applied to the distal end of each construct by a material testing machine under control of a motion analysis video system. The specimens were arranged into five implant groups of eight specimens each. No test group developed deformity and movement of the fracture gap greater than 2 mm with a load of 100 N. Increasing the load to 250 N revealed statistically significant differences in stiffness and failure load betwe…
Assessment of Lower Limb Load Distribution in Patients Treated with the Ilizarov Method for Tibial Nonunion
2021
BACKGROUND Successful treatment of tibial nonunion should lead to a complete bone union, lack of pain, and pathological mobility of the lower extremity, as well as to the achievement of satisfactory joint mobility and muscle strength, which in turn improves its biomechanics. The objective of this study was to assess the load placed on the lower limbs in patients subjected to treatment with the Ilizarov method due to aseptic tibial nonunion. MATERIAL AND METHODS This research involved 24 participants (average age, 55 years). All were diagnosed with aseptic tibia nonunion and treated with the Ilizarov external fixator between 2000 and 2017. The control group was matched to the treated group i…
Numerical study for a new methodology of flaws detection in train axles
2013
Train loads and travel speeds have increased over time, requiring more efficient non-destructive inspection methods. Railway axles are critical elements; despite being designed to last more than 20 years several cases of premature failure have been recorded. Train axles are inspected regularly, but the limits associated to the traditional inspection technologies create a growing interest towards new solutions. Here a novel non-destructive inspection method of in-service axles based on non-contact data collection is presented. The propagation of surface waves, generated by a thermo-elastic laser source, is investigated using a finite element method based on dynamic explicit integration. Coup…
Experimental and analytical response of masonry elements under eccentric vertical loads
2005
The flexural behaviour of masonry rectangular cross-sections is studied in order to characterize the mechanical behaviour of structural elements under axial eccentric loads by means of a proper law. First the experimental response of walls under vertical centred loads is observed and a stress-strain law depending on two parameters is given in order to fit the experimental results. Subsequently the behaviour of walls nominally equal to the walls mentioned before is investigated under eccentric vertical loads, and the response is observed in terms of moment-curvature relation. To this point a comparison is made between the moment-curvature response obtained experimentally and the moment-curva…
Time‐gated Raman and laser‐induced breakdown spectroscopy in mapping of eudialyte and catapleiite
2019
Abstract Raman analysis of rock samples containing rare earth elements (REEs) is challenging due to the strong fluorescence, which may mask the weaker Raman signal. In this research, time‐gated (TG) Raman has been applied to the construction of the mineral distribution map from REE‐bearing rock. With TG Raman, material is excited with a short subnanosecond laser pulse, and the Raman signal is collected within a picosecond‐scale time window prior to the formation of a strong fluorescent signal by means of single‐photon avalanche diode array. This allows signal readout with a significantly reduced fluorescence background. TG Raman maps are used to reveal the location of valuable minerals and …
Aluminium distribution in an Earth's non–primitive lower mantle
2020
The aluminium incorporation mechanism of perovskite was explored by means of quantum mechanics in combination with equilibrium/off-equilibrium thermodynamics under the pressure-temperature conditions of the Earth's lower mantle (from 24 to 80 GPa). Earth's lower mantle was modelled as a geochemically non-primitive object because of an enrichment by 3 wt% of recycled crustal material (MORB component). The compositional modelling takes into account both chondrite and pyrolite reference models. The capacity of perovskite to host Al was modelled through an Al2O3 exchange process in an unconstrained Mg-perovskite + Mg-Al-perovskite + free-Al2O3(corundum) system. Aluminium is globally incorporate…
Experimental design of the bearing performances of flax fiber reinforced epoxy composites by a failure map
2018
Abstract This paper represents the first effort aimed to the investigation of the pin/hole contact stress and failure mechanisms of epoxy composites reinforced with woven flax fabrics, underwent to tensile bearing tests. In particular, the maximum loads and failure modes are evaluated at varying the laminate geometrical configuration. In order to optimize the use of polymer composites reinforced with flax fibers in structural applications, an experimental failure map, identifying main failure modes of mechanically fastened joints, is obtained as function of hole diameter, distance of the hole from the free edge of the laminate and laminate width. Moreover, a theoretical approach based on th…
Mesenchymal stem cell proliferation and differentiation on load-bearing trabecular Nitinol scaffolds.
2013
Bone tissue regeneration in load-bearing regions of the body requires high-strength porous scaffolds capable of supporting angiogenesis and osteogenesis. 70% porous Nitinol (NiTi) scaffolds with a regular 3-D architecture resembling trabecular bone were produced from Ni foams using an original reactive vapor infiltration technique. The "trabecular Nitinol" scaffolds possessed a high compressive strength of 79 MPa and high permeability of 6.9×10(-6) cm2. The scaffolds were further modified to produce a near Ni-free surface layer and evaluated in terms of Ni ion release and human mesenchymal stem cell (hMSC) proliferation (AlamarBlue), differentiation (alkaline phosphatase activity, ALP) and …
Positron Microscopy Studies of Wear Tracks on a Copper Surface
2014
Positron microscopy was used for studies of defects induced by ball indentation or sliding on the surface of well-annealed copper samples. A focused positron beam of 24.5-keV energy was used to scan the deformed region of the indenter impression, and measurements of the annihilation line parameter were performed. In the case of ball indentation, the measured defect distribution correlates well with the von Mises stress distribution of the Hertz contact and the von Mises yield criterion. For the wear track produced by pin on disc dry sliding, an asymmetric defect distribution near the wear track is observed. It indicates the presence of a tangential force that additionally deforms the sample.