Abstract: Toggle jacks are simple mechanisms used to drive large loads short distances and to lift the heavy loads. It also have the advanced feature of rotating the parts about their axis where there is not enough space to move the load. The power screw design of a common Toggle jack reduces the amount of force required by the user to drive the mechanism. Most of the Toggle jacks are similar in design, consisting of eight main members out of whom four are driven by a power screw and rest of four by loading condition. In this report, a unique design of a Toggle jack is used to lift the heavy loads at the stable state with the unique condition. In toggle jack screw and nut are main components. A screw is moving part and nut is a stationary part. Both the parts always work in meshing condition. Therefore there are stresses like shear and tensile stresses induced in materials which are responsible for failure of screw. While a nut has bearingstress. Different materials of screw and nut can induce different magnitude of stresses so it is necessary to select a pair of material combination in such a way that a pair gives induced stress within safe limit. Here we have taken different material combinations of screw and nut & based on that analytical design is done for on different loading condition from 1KN to 5KN. It is also assumed that the nominal diameter of screw and material for link are same for all loads.
Table-2 shows the highest bearingstress at failure achieved in each laminate for 5 mm and 10 mm holes in the finger-tight and clamped condition. There are a number of aspects of behaviour apparent from the results in the table. With regard to the magnitude of the bearing stresses at failure achieved they are greater than the base- line tensile strengths of the laminates, reported in Belmonte et al. (2004). True bearing failure was seen more readily in the quasi-isotropic lay-ups compared to the cross-ply lay-ups for the range of joint geometries investigated here. This reflects a combination of the stress state around the hole and the relative values of the tension and (constrained) compression strengths. It is likely that testing the cross-ply at larger W/d (W/d >3) could lead to further increase in strength and a change in failure mode. It is apparent that the bearingstress at failure of the joints with the 5 mm diameter holes exceed those of the joints
McCarthy, McCarthy and Gilchrist  found that net-tension modes were susceptible to occur in multi-bolt joints due to by-pass loading transfer within adjacent bolts. It was suggested the outer bolts transfer bearingstress to adjacent bolts leading to tendency for net-tension failure to occur. Most of strength prediction works in bolted joint problems were implemented within finite element framework such as progressive damage modelling. Failure criterion and degradation law used are Hashin  formulation and Yamada-Sun  law respectively in progressive damage modelling implemented by McCarthy, McCarthy and Lawlor  work based on ply-by-ply basis. Three steps were implemented as follows: (i) stress analysis, (ii) implementation of failure criteria and (iii) degradation of material properties. McCarthy used homogeneous material properties based on Classical Laminate Plate Theory (CLPT) used as elastic material properties, however this theory is applicable to unidirectional composites, they also elaborate the use of proper contact interaction between bolt-hole and other contact regions. However, available CLPT theory is not applicable to woven fabric composites as there are existing crimping region. Ishikawa and Chou  proposed notable three classical models based on Classical Laminated Plate Theory (CLPT) of 2-D woven fabric composites that able to predict thermo-elastic properties. However, these formulations were based on micro- scale modelling known as representative volume element (RVE), complex mathematical formulations were involved as multi-scale modelling were involved leading to its impractical use.
between the hole and the plate edge. They also found that damage distributions in composite- composite joints is not uniform along the thickness, more damage is localised where damage onset was observed. More uniform damage distribution in composite-aluminium configurations has been found. Secondary bending and bolt bending in single-lap joint create a non-uniform contact stress distribution between the bolt and hole edge. Ireman  developed a bolted single-lap joint model to investigate non-uniform stress distributions through the thickness of the laminate in the bolt vicinity. He modelled a rigid plate to represent the lateral support used to eliminate secondary bending. Good agreement between measured and calculated strain were obtained. However, secondary bending was greater in the experiments than the FEA models due to using overly-stiff elements. A clamped condition case reduced the strain level compared to finger-tight conditions, and higher strain level were found in countersunk bolts compared to protruding head bolts. Ekh and Schon  studied the effect of secondary bending and found that it has potential to shift the failure mode and affect the strength. Secondary bending increased the contact area between bolt and hole edge which reduced the bearingstress and increased the bearing strength. Secondary bending also increased the plate bending and generated more severe net-tensile conditions leading to reduced net-tensile strength. Therefore, it is difficult to predict the bearing strength with this effect of secondary bending and this must be evaluated on an individual basis.
Specimen S-3 is intended to confirm the characteristics of specimen in the area near the edge of the buildings, the axial stress of which is fixed 10MPa up to the design level shear strain 250%, and varied in proportion to shear strain from design level 250% up to breakage level 450% as shown in Figure 3. S-4 is a specimen using the concrete compressive strength 60MPa. In the case of shear strain near breakage limit, effective cross sectional area of upper end and lower end of elastomeric isolator decreases extremely down to approximately one sixth of loaded area at shear strain 0%. Figure 5 shows an example of analysed contact pressure by FEM at the bottom of lower flange surface. As shown in Figure 4 and Figure 5, it is concerned that concrete may have bearing failure due to the large bearingstress at the upper surface of pedestal under the condition acting high axial stress at breakage level shear strain. Specimen S-4 is intended to confirm the supporting function of pedestal under the condition acting high axial stress at breakage level shear strain by using the concrete compressive strength 60MPa, expecting the effect of high-strength concrete with increased bearing strength.
This paper predicts the influence of couple stresses on the lubrication of porous inclined multi stepped composite bearings. According to the Stokes theory, the couple stress parameter characterizes the effects of couple stresses on the bearing characteristics of the system. If we assume l * 0 then the dimensionless Reynolds equation reduces to the newtonian lubricant case. When the value of
The present work aims at investigating the stability of retained austenite upon increas- ing temperatures and number of compressive stress cycles in two popular martensitic bear- ing steel grades 100Cr6 and 100CrMnSi6-4, their chemical compositions are given in Ta- ble 1. Whilst 100Cr6 is commonly employed for small to medium bearing applications, 100CrMnSi6-4 allows greater hardenability due to its relatively high Mn and Si contents and can be utilised for medium to large components . In the ﬁrst part of the work, the in situ thermal stability of retained austenite whilst gradually increasing temperature is studied, as well as its decomposition mechanisms and the associated transformation-induced strain,
The first base isolation was registered as a patent in 1800’s, and the one of the first few buildings that used the base isolation was in early 1900’s in Tokoyo Imperial Hotel, in which after that structural bearing commercially used in bridge construction. The first material used for BI was made of lead rubber bearing (LBR) providing high flexibility and damping. In early 1980’s the high damping rubber (HDR) was used in US. But the drawback was that these products have no restoring force where they dislocate after the shaking force. The developed friction pendulum system (FPS) in shape of spherical surface overcomes this demerit of sliding bearing, and providing a restoring force. “Since 1840’s the natural rubber has been used for base isolation, through the process of material development synthetic rubber or polytetrafluoroethylene (PTFE) which is developed by DuPont was used, and designed for 50 years or more. About 40 years ago, the elastomeric (layered rubber and steel) was used in bridges, providing an increase of 7% in stiffness after 37 years from installation, with oxidation restriction to 10 mm to 20 mm. Few design equations were developed for base isolation and bearing by codes committees like UBC, IBC2000, FEMA273, NZS4203, CHBDC S6, AISI and AASHTO LRFD for bridges. According to the CHBDC, clause 11.6.11, it states “Bearing shall support and transfer all loads while accommodating translations and rotations in the structure”, also added in clause 188.8.131.52 that “Bridges with superstructures supported on bearings shall be designed to permit the jacking of the superstructure. Jack and shimming locations shall be shown on the drawings. The design shall allow for movement at the permanent bearing locations sufficient to permit bearing replacemet”. Building should have the same provisions for bearing and its replacement as per CHBDC as well. Nevertheless more provision must be added for building since it is more complex structure than that of bridges. Due to the presence of the base isolation, the superstructure of the building above ground needs a transfer slab. sometimes lateral movement is restrained at selected bearing. Design procedures of BI building can be listed as:
The sacrum is a wedge shaped bone that makes up part of the pelvis. It transmits the weight of the body to the pelvic girdle. As the name suggests, sacral insufficiency frac- tures occur when the quality of the sacral bone has become insufficient to handle the stress of weight bearing. The bone has lost some of its supporting structure and has become weak. Since this is usually because of osteoporosis, sacral insufficiency frac- tures occur most often in older women. This guide will help you understand
Phenylboronic acid-decorated SPB NPs with diameters of 30 nm, 50 nm and 150 nm were prepared in a complete aqueous solution without any organic solvent. By virtue of the affinity between phenylboronic acid and SA and the intrinsic biological property of SP, such SPB NPs could not only actively target the SA overexpressed tumor model, but also decrease tumor IFP and solid stress, improving tumor microenvironment. The in vivo experiments demonstrated that pretreatment with SPB30 significantly increased the accumulation of free DOX in tumor, thus enhancing the antitumor efficiency of free DOX, owing to the reduction of tumor IFP and solid stress induced by pretreated with SPB30. Moreover, due to the size effect, the DOX-loaded SPB30 itself also showed much greater efficacy in accumulating in tumor tissue, impeding tumor growth and prolonging the lifetime of mice, compared to other groups.
Ti% alloy compacts have been evaluated, and the results related to this aspect are presented and discussed. The possibility to develop the weldability of NbTi/CNTs nanocomposites  with TA6V alloys to form NbTi/CNTs/TA6V by in situ spark plasma sinter design and manufacturing of prosthesis is achieved after a technology of the machining of the spacer, die and matrix of the FCT sintering machine of the more complicate geometry of the Total Hip and Knee Arthroplasty (THA, TKA) prosthesis. The prosthesis ball and joint is made of NbTi and NbTi-CNT because it offers good ductility and reduce strain, stress and bearing surfaces and wear resistance by addicting of the CNT at the hip, the body of the prosthesis is made of TV6A welded with the ball and introduced with the femur one offering him a good tenacity, NbTi/CNTs nanocomposites has required mechanical and chemical properties for this kind of biomedical applications. First, nanoindentation tests were performed with a coupled analysis in a scanning electron microscope to show the gradient properties the interface between the TA6V bulk substrate and the NbTi/CNTs adding.
the lens has been subject to dynamic recrystallization dur- ing which there would have been potential for the grains to change size and shape. The grain-size difference within the lens may reflect development of the finer population where stress was preferentially partitioned resulting in more in- tense grain-size reduction, whereas the courser population, affected by lower stresses, may reflect more limited grain- size reduction. Such stress partitioning is consistent with dif- ferential stress estimates made based on grain-size piezom- etry that indicated higher stresses associated with smaller grain sizes.
Abstract: Stress fractures account for between 1% and 20% of athletic injuries, with 80% of stress fractures in the lower extremity. Stress fractures of the lower extremity are common injuries among individuals who participate in endurance, high load-bearing activities such as running, military and aerobic exercise and therefore require practitioner expertise in diagnosis and management. Accurate diagnosis for stress fractures is dependent on the anatomical area. Anatomical regions such as the pelvis, sacrum, and metatarsals offer challenges due to diffi- culty differentiating pathologies with common symptoms. Special tests and treatment regimes, however, are similar among most stress fractures with resolution between 4 weeks to a year. The most difficult aspect of stress fracture treatment entails mitigating internal and external risk factors. Practitioners should address ongoing risk factors to minimize recurrence.
A theoretical analysis of the combined effect of journal speed and couple stress fluids (CSF) on the performance characteristics of a cavitated finite journal bearing (FJB) has been presented in this paper. Depending on the Elrod cavitation algorithm (ECA), the solution to the modified Reynolds equation is achieved. The bearing parameters are affected by both the journal speed and CSF. From the results obtained, it is detected that the non- Newtonian lubricants (CSF) produce enhanced in the fill-film pressure, load-capacity, as well as reduces the Sommerfield number and a small drop in the values of the bearing side leakage flow. The results obtained in this work specify that the characteristics of the bearing are affected significantly by this effect. The achieved results have been compared with that published by other works for the bearing operating with pure lubricant and showed to be in a good agreement.
An integral shaft bearing is popular for higher specific load carrying capacity, preventing misalignment defects and eliminating the risk of undesirable distortion of the bearings, rather than conventional one. Integral shaft bearing is used to reduce rotational friction and support radial and axial loads friction in bearings which cause an increase of the temperature and Stresses inside the bearing. If the heat produced cannot be adequately removed from the bearing, the temperature might exceed a certain limit, and as a result the bearing would fail. To analyze the heat flow, temperature distribution and stresses in a bearing system, a typical integral shaft bearing and its environment has been modeled and analyzed using the famous finite element tool ANSYS. In this study we investigate structural and thermal characteristics performance of integral shaft bearing to Analyze temperature distribution and thermal elongation due to friction also its effect on bearing clearances and vice-versa.
In Fig.7 and 8 the squeezing time of spherical bearing t plotted with h s , the mean height of roughness asperities for various values of couple stress parameter l . As the mean height of roughness asperities h s increases, the squeezing time t increases with the increase of couple stress parameter l . It is observed from these graphs that the mean height of roughness asperities h s increases, the squeezing time t increases for low values of φ and the roughness parameter decreases for high values of φ . The lower values of φ may represent the case of transversal roughness where as the higher values of φ may correspond to longitudinal roughness.
The weight of the blower fan rotor is about 240 kg and the rotating speed is 5400 r/min. It is a large, vertical, high-speed rotor, and the rotor’s length is about 1.5 m,. This is a challenging project in theory and practice. The research status of the auxiliary bearing was summarized in the paper. A sort of auxiliary bearing scheme was proposed. MSC.Marc was selected to analyze the vibration mode and the natural frequency of the rotor. The scheme design of auxiliary bearing and analysis result of rotor dynamics offer the important theoretical base for the protector design and control system of electromagnetic bearing of the blower fan.
performance can be visualised by inspecting the overlap of distribution of both binary responses plotted on the same axis, as shown in Figure 5.1. This plot shows four dis- tribution curves: two for each data set. The two curves on the left-hand side of the plot relate to those sites within each data set that have been classified as non-fish- bearing. The curves show the occurrence frequency for the probabilities predicted by the model. As would be expected, most of the predicted probabilities for the non- fish-bearing streams are below 0.5—that is, the model predicts that for most of these streams, there is a less than 50% chance that these streams are fish-bearing. Probabil- ities peak at around 0.2, with a smaller peak around 0.45. The tail of the curves does extend above 0.5, which accounts for the 10% to 20% of non-fish-bearing streams not correctly predicted by the model.