A Numerical Study of the Induced Stresses in the Separation Points of the Tensile Element (Chain) of the Plate Conveyor Used in the Blowing Unit in Water Factories

The Induced Stresses in Tensile Element Joints (chain) were Studied in Two Phases: The first phase is to conduct a design study of the plate conveyor to determine the maximum tensile strength to which the joint is exposed. Then build two models, the first one represents a single joint with its components (wedge- copper ring- plate) with the basic dimensions and measurements of the chain. The second model was designed with new dimensions to suit the conveyor's working conditions. In the second phase, the three-dimension finite elements method was used to identify the stresses induced in the joint for both models and then compare the results to identify the model that shows the best performance. The result showed that increasing the external thickness of the joint by double in the proposed model up to the value of 6 mm was able to provide a homogeneous distribution of the main induced stress, which contributed to reducing the critical values of these stresses compared to the induced stresses in the model currently used. Consequently, increasing the external thickness of the joint has played an important role in reducing stresses, which leads to an increase the service life of the plate conveyor chain.

Mechanical and numerical characterization of ceramic femoral components for hip resurfacing arthroplasty

Hip resurfacing arthroplasty may have distinct advantages for young and active patients, but large metal-on-metal bearings can be associated with increased wear, adverse tissue reactions and higher rate of implant loosening. Ceramic wear couples are a commonly used alternative to metals and therefore might be an alternative for hip resurfacing arthroplastys. The aim of this study was to evaluate the mechanical strength of femoral components made of an alumina-toughened zirconia composite by means of experimental testing and finite element analysis. For the mechanical characterization, ceramic femoral components (Ø: 48 mm) were tested under compression loading experimentally until fracture occurred or a maximum load of 85 kN was obtained. The femoral components were either loaded against a ceramic cup or a copper ring (outer diameter Ø: 7.0 mm). In addition, the complex geometry of the ceramic femoral component was simplified, and only the stem was loaded in a cantilever test until fracture. In addition, the fracture tests were numerically simulated to investigate the influence of additional loading conditions and geometric parameters, which were not experimentally tested. The experimental data were used for validation of the finite element analysis. None of the tested ceramic femoral components fractured at a compression load of 85 kN when they were loaded against a ceramic cup at an inclination angle of 45°. When the femoral components were loaded against a copper ring, the femoral components fractured at 29.9 kN at a testing angle of 45°. The fracture load was reduced when an angle of 30° and increased when an angle of 60° was simulated. Using an experimental cantilever test, the stem of the femoral component fractured at 1124.0 N. When the stem length was increased or the diameter was reduced by 10% in the finite element analysis, the fracture load was reduced. Decreasing the length or increasing the diameter led to an increase of the fracture load. The strongest influence was found for the reduction of the transition radius of the stem, with a decrease of the fracture load up to 27.2%. The analyzed femoral components made of alumina-toughened zirconia (ATZ) showed sufficient mechanical capability to withstand high loadings during unfavorable loading conditions. However, further biomechanical and tribological investigations are required before clinical application.

Fabrication and characterization of magnetic nanocomposites by electric fields assisted electrospinning

A magnetic and electric fields assisted electrospinning, in which a charged copper ring was placed between the needle and the two paralleled magnets receivers, was presented to produce aligned polyacrylonitrile/graphene/Fe3O4 (PAN/Gr/Fe3O4) magnetic composite nanofibers. Characterizations of the magnetic composite nanofibers were investigated by means of scanning electron microscopy, Fourier transform infrared spectroscopy, high-resistance meter, and other methods. The results showed that Gr and Fe3O4 nanoparticles are suitable additives to improve alignment degree and conductive properties of nanofibers.

Fabrication of asymmetric-gradient-concentric ring patterns via evaporation of droplets of PMMA solution at different substrate temperatures

Asymmetric-gradient-concentric ring patterns are fabricated via evaporating a PMMA solution droplet with a circular copper ring as template. Various micro-patterns are formed in the trench between the polymer rings.

Effect of Cross Section Size on Ductility and Fragmentation of Copper Ring at High Strain Rate Loading Conditions

In the present work, different copper ring samples geometries with a small aspect ratio of 0.5 or 1 were subjected to an experimental study under electromagnetic expanding ring test conditions. The experimental multiple ring tests were performed under similar loading conditions, that is, the applied maximum expansion velocities covered a range from 128 to 147 m/s (7.4 103s-1) for all ring samples geometries, with the exception of rings with a cross section of 1 mm x 0.5 mm. For these rings, the averaged maximum expansion velocity was higher and equal to 195 m/s (1.2 104s-1). The results of experimental investigations revealed a minor influence of the applied cross section sizes on ductility of copper rings, whereas its fragmentation seems to be dependent on a ring cross section area.

Investigation of Residual Stresses and some Elastic Properties of Brush-Plated Gold and Silver Galvanic Coatings

Nickel-hardened gold and silver coatings were brush-plated from a commercial SIFCO Dalic Solution (Gold Hard Alloy), Code SPS 5370, and Silver Hard Heavy Build, Code SPS 3080, on unclosed thin-walled copper ring substrates. To determine residual stresses, the conventional curvature method (common among the electrodeposition methods) was applied, where the substrate was coated with certain thickness and then the slit increment (bending deflection) of the substrate was measured as an experimental parameter. Residual stresses on gold coatings were also determined by X-ray diffraction (XRD) based on the sin2 method. The values of residual stresses determined by the curvature method and by the XRD technique were comparable. Relaxation of residual stresses was observed. An equation for approximation of the change of residual stresses was applied assuming that the dependence of residual stresses on relaxation time is linear-fractional. The surface morphology and microstructure of the coatings was studied by means of scanning electron microscopy (SEM). The magnitudes of the modulus of elasticity and of the nanohardness of the coatings were obtained by instrumented indentation.