Journal articles on the topic 'Design stresses'
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Pargaonkar, C. S., and Maneesh Batrani. "Expansion Joint Design, Manufacture and Testing for Large Capacity Steam Turbines." Applied Mechanics and Materials 592-594 (July 2014): 1539–43. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.1539.
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The rapidly growing trend for higher capacity steam turbines with large steam flows demand the use of long lengths and large size pipes. Thermal expansions of up-to 50mm and pipe diameters up-to 2600mm are required to be dealt with calling for the use of Expansion Joints to control the stresses in both the pipes as well as the end equipment. The bellows in the Expansion Joints used for the steam turbine application are stretched to their limiting values of the stresses in order to make them as flexible as possible with the aim of limiting the pipe and end equipment operational stresses. Three fundamental types of loading are presented to provide insight into the way bellows convolutions are stressed during operation. The optimization of the bellows profile geometry is discussed briefly. A comparison of the resulsts obtainied by proven computational methods as well as by using international EJMA standard is made to highlight the safety built in the well established methods used.
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Sandström, Rolf, and Bo Ivarsson. "Influence of scatter in yield stresses on design stresses at elevated temperature." Materials & Design 7, no. 2 (March 1986): 95–100. http://dx.doi.org/10.1016/s0261-3069(86)80008-5.
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VOGLER, FALKO, and PETER GROCHE. "CRITERIA FOR TOOL DESIGN IN HYDROFORMING." Journal of Advanced Manufacturing Systems 07, no. 01 (June 2008): 171–74. http://dx.doi.org/10.1142/s0219686708001309.
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Closing forces and internal pressure lead to stresses and strains in hydroforming dies. The deflection of the die influences the accuracy of the hydroformed products. The influence of the die geometry on stresses and strains in the die is being examined fundamentally. Additionally, the location of the closing force transmission is discovered to be crucial. The objectives of this research were to determine the demands on the hydroforming die and to reduce failure-critical stresses.
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Zhao, Yuan Qin. "Study on Materials Flow Destruction Causes to the Shape Change with New Method of Proving a Specific Energy Theory." Advanced Materials Research 675 (March 2013): 169–71. http://dx.doi.org/10.4028/www.scientific.net/amr.675.169.
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The three principal stresses of unit body correspond to the three circles of stress. Each circle of stress corresponds to one of the biggest shear stresses. Each of the biggest shear stresses corresponds to a shear stress’s specific energy. Therefore, specific energy of unit body is solved. It is compared with specific energy of shear stress, staying a dimensional state of stresses with materials flow destruction. And people can get a common formula about specific energy theory of the shape change during the engineering design. The new method’s proving process is very simple, and the nature of failure mechanism is clearer.
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Keste, Appasaheb Adappa, Shravan Haribhau Gawande, and Chandrani Sarkar. "Design optimization of precision casting for residual stress reduction." Journal of Computational Design and Engineering 3, no. 2 (November 6, 2015): 140–50. http://dx.doi.org/10.1016/j.jcde.2015.10.003.
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Abstract Normally all manufacturing and fabrication processes introduce residual stresses in a component. These stresses exist even after all service or external loads have been removed. Residual stresses have been studied elaborately in the past and even in depth research have been done to determine their magnitude and distribution during different manufacturing processes. But very few works have dealt with the study of residual stresses formation during the casting process. Even though these stresses are less in magnitude, they still result in crack formation and subsequent failure in later phases of the component usage. In this work, the residual stresses developed in a shifter during casting process are first determined by finite element analysis using ANSYS® Mechanical APDL, Release 12.0 software. Initially the analysis was done on a simple block to determine the optimum element size and boundary conditions. With these values, the actual shifter component was analyzed. All these simulations are done in an uncoupled thermal and structural environment. The results showed the areas of maximum residual stress. This was followed by the geometrical optimization of the cast part for minimum residual stresses. The resulting shape gave lesser and more evenly distributed residual stresses. Crack compliance method was used to experimentally determine the residual stresses in the modified cast part. The results obtained from the measurements are verified by finite element analysis findings. Highlights This paper focus on analytical, numerical and experimental design optimization of shifter. Performed design optimization by finite element analysis and experimental of live industrial problem. The results can applicable as a basis of design and optimization of new type of the automotive parts. The results of the current work present the actual behavior of induced stresses.
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Belabed, Youssouf, Bachir Kerboua, and Mostapha Tarfaoui. "New design for reducing interfacial stresses of reinforced structures with FRP plates." International Journal of Building Pathology and Adaptation 37, no. 2 (April 8, 2019): 196–207. http://dx.doi.org/10.1108/ijbpa-09-2018-0073.
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Purpose The sustainability of the structures is not only a technical goal, but also a matter of social and environmental values. This requires the researchers to use very rigid, highly durable and corrosion-resistant composite structures in order to achieve the technical, environmental and social goals. The purpose of this paper is to present an original work on reducing the interfacial stresses of bonded structures with fibre-reinforced polymers (FRP) plates based on new taper design. Design/methodology/approach In this proposed concept, the effect of combined taper is investigated on reducing interfacial stresses, attempting to enhance the structure performance and address the debonding problem that comes with reinforcing techniques. This research is carried out by using finite element analysis, incorporating many new parameters. Findings As a result, a new solution is discovered that combined taper in both adhesive layer and composite laminate, which significantly reduces the interfacial stresses at the end of the FRP plate. Additionally, a parametric study is carried out in order to determine the optimal configurations of taper dimensions as well as other parameters that influence the stress concentration distribution at the edge of the adherends. Practical implications This new design regarding the reduction of interfacial stresses will help in increasing the lifespan of damaged structures reinforced by FRP composites, preserving thus its technical, historical and social values. Originality/value The paper uses straight, concave and convex fillets with inverse taper as a new design solution with new parameters including thermo-mechanical loads and pre-stressed FRP plate with multi-layer, fibre orientation and shear-lag effects.
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Mešić, Elmedin, Enis Muratović, Lejla Redžepagić-Vražalica, Nedim Pervan, Adis J. Muminović, Muamer Delić, and Mirza Glušac. "Experimental & FEM Analysis of Orthodontic Mini-Implant Design on Primary Stability." Applied Sciences 11, no. 12 (June 12, 2021): 5461. http://dx.doi.org/10.3390/app11125461.
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The main objective of this research is to establish a connection between orthodontic mini-implant design, pull-out force and primary stability by comparing two commercial mini-implants or temporary anchorage devices, Tomas®-pin and Perfect Anchor. Mini-implant geometric analysis and quantification of bone characteristics are performed, whereupon experimental in vitro pull-out test is conducted. With the use of the CATIA (Computer Aided Three-dimensional Interactive Application) CAD (Computer Aided Design)/CAM (Computer Aided Manufacturing)/CAE (Computer Aided Engineering) system, 3D (Three-dimensional) geometric models of mini-implants and bone segments are created. Afterwards, those same models are imported into Abaqus software, where finite element models are generated with a special focus on material properties, boundary conditions and interactions. FEM (Finite Element Method) analysis is used to simulate the pull-out test. Then, the results of the structural analysis are compared with the experimental results. The FEM analysis results contain information about maximum stresses on implant–bone system caused due to the pull-out force. It is determined that the core diameter of a screw thread and conicity are the main factors of the mini-implant design that have a direct impact on primary stability. Additionally, stresses generated on the Tomas®-pin model are lower than stresses on Perfect Anchor, even though Tomas®-pin endures greater pull-out forces, the implant system with implemented Tomas®-pin still represents a more stressed system due to the uniform distribution of stresses with bigger values.
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Ayoub, Mai, Mohamed EL-Anwar, and Mazen I. Negm. "Arthroscopic Suture Anchor Design Finite Element Study." Open Access Macedonian Journal of Medical Sciences 9, A (July 22, 2021): 562–66. http://dx.doi.org/10.3889/oamjms.2021.6409.
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AIM: This in-vitro study investigated arthroscopic suture anchors’ main design parameters effect on surrounding bone. METHODS: Thirty-dimensional arthroscopic suture anchor designs’ models were created on engineering CAD software by changing thread profile, pitch, and anchor tip profile as design parameters. These models were imported into ANSYS Workbench for finite element analysis. Bone was simplified and modeled as two coaxial cylinders. Tensile vertical load of 300 N, and oblique at 45º to the vertical axis, were applied to each model as two loading conditions while the simplified bone base was fixed in place as a boundary condition. RESULTS: The finite element analyses on all models under both loading conditions showed stresses within physiological limits on bone. Trapezoidal teeth and inclined cut teeth designs showed the lowest values of stresses and deformations respectively on the bone under oblique loads, while curved tooth and square tooth designs showed the lowest values of stresses and deformations respectively on the bone under vertical loads. General ascending or descending trend was recorded by increasing pitch from 1.2 to 1.5 to 1.8 mm on the total deformation and maximum Von Mises stress on bone and anchor body. Tapered tip slightly increased bone and anchor stresses. CONCLUSION: Arthroscopic anchors thread profile has minor affect on cortical bone behavior. Trapezoidal teeth, square tooth, and inclined cut teeth profiles showed the lowest values of stresses and deformations on cortical bone. Increasing thread pitch of arthroscopic suture anchors increases or decreases stress on the bone, and anchor body according to thread profile edges. Anchor tip profile negligibly affects both deformations and stresses on bone and anchor body.
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Rocha, L. A. O., S. Lorente, and A. Bejan. "Vascular design for reducing hot spots and stresses." Journal of Applied Physics 115, no. 17 (May 7, 2014): 174904. http://dx.doi.org/10.1063/1.4874220.
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Jobson, D. A. "Asymptotic and reference stresses for design by analysis." Nuclear Engineering and Design 98, no. 3 (January 1987): 395–400. http://dx.doi.org/10.1016/0029-5493(87)90018-5.
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Lin, Cui, D. H. Steve Zou, and Haoran Sun. "Exploration of Measurement Methods of 3D In-Situ Stresses in Rock Masses." International Journal of Georesources and Environment 5 (March 1, 2019): 1–13. http://dx.doi.org/10.15273/ijge.2019.01.001.
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This paper gives an overview of the measurement methods for the 3D in-situ stresses. Rock masses in the Earth’s crust are stressed in a natural stress state, which has six components in three dimensions. They are called “in-situ stresses” or “field stresses” with three principal stress components. Reliable estimate of the in-situ stresses in the rock mass is essential and vital for proper planning and design, underground excavation, mineral resource exploitation and ground stability control in geotechnical, mining and petroleum engineering. The basic principles of the measurement methods, including overcoring, hydraulic fracturing, back analysis, borehole slotting, flat jack, geophysical, and borehole breakout, are introduced. The advantages and limitations are discussed and compared. Methods that measure borehole deformation and strains during overcoring appear most common and are the only methods for the complete 3D stresses. Other measurement methods generally provide results of the orientations and/or magnitudes of some components of the in-situ stresses, mostly the maximum and the minimum stresses in the plane perpendicular to the borehole. In some methods the vertical stress is assumed as a principal stress.
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Tarr, Scott M., Matthew J. Sheehan, and Ahmad Ardani. "Mechanistic Design of Thin Whitetopping Pavements in Colorado." Transportation Research Record: Journal of the Transportation Research Board 1730, no. 1 (January 2000): 64–72. http://dx.doi.org/10.3141/1730-08.
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A mechanistic design procedure was developed for the state of Colorado to determine the required concrete thickness of thin [12.7 cm to 17.8 cm (5 in. to 7 in.)] whitetopping overlays on asphalt pavements. Field testing was conducted to evaluate critical load locations for whitetopping with joint spacing up to 3.66 m (12 ft). The load-induced flexural strains were used to calibrate fully bonded stresses computed by applying finite element analysis techniques to partially bonded stresses measured in the field. For each test section, load testing was conducted throughout the course of a day to develop a temperature correction for the critical stresses derived for zero temperature gradient (zero slab temperature curling). Equations predicting the critical concrete flexural stresses and asphalt concrete strains for use in whitetopping were developed. A mechanistic design procedure is described that allows the evaluation of trial whitetopping thicknesses and joint spacings. The procedure computes the concrete and asphalt fatigue life for specific material properties. Iterations are required to determine the appropriate parameters that provide the required design life for both concrete and asphalt layers. In addition to the design procedure, the effect of surface preparation during construction was studied by comparing identical slabs constructed on milled and unmilled asphalt. It was concluded that existing asphalt pavement should be milled and cleaned before concrete placement for an overall reduction of 25 percent in the critical load-induced stresses. However, new asphalt, such as that placed in repair patches, should not be milled before concrete placement to avoid a 50 percent increase in critical load-induced stresses.
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Warrior, N. A., A. P. Sime, T. H. Hyde, and H. Fessler. "The design of overlapped crankshafts. Part 2: Web shape." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 216, no. 8 (August 1, 2002): 655–62. http://dx.doi.org/10.1177/095440700221600804.
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The boundary element (BE) technique was used to analyse nine widely different shapes to investigate the effects of crankweb shape on the peak stresses in the crankpin/web and journal/web fillets and on the crankshaft. Under radial three-point bending, pure radial bending and torsion, increasing the web thickness or increasing the overlap reduces the peak fillet stresses and stiffens the crankshaft. Empirical equations are presented for the maximum stresses in both types of bending, torsion, web spread and twist.
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Jokūbaitis, Vidmantas, and Linas Juknevičius. "ANALYSIS OF METHODS FOR CALCULATING THE WIDTH OF NORMAL CRACKS IN REINFORCED CONCRETE STRUCTURES." Engineering Structures and Technologies 1, no. 1 (May 17, 2009): 23–39. http://dx.doi.org/10.3846/skt.2009.03.
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The width of normal cracks at the level of tensile reinforcement was calculated according to various methods using the data obtained from experimental tests on reinforced concrete beams (without reinforcement pre-stress), pre-cast reinforced concrete slabs and ribbed roof slabs. Th e numerical results were compared to actual crack widths measured during the experimental tests. Also, the crack widths of pre-stressed reinforced concrete beams were calculated according to various methods and compared with each other. Th e following conclusions were reached based on the analysis of numerical and experimental results: 1) Design stresses in tensile reinforcement calculated according to [STR] and [EC] design codes are very similar, although the calculation of such stresses is more logical and simple according to [EC]. Design stresses calculated according to [RU] are greater due to the estimation of the plastic deformations of concrete in the compressive zone. Th e method proposed by Rozenbliumas (Розенблюмас 1966) estimates tensile concrete above the crack peak, and thus allows a more accurate calculation of stresses in tensile reinforcement (Fig 3). Therefore, the latter stresses in pre-stressed RC beams may be decreased by 10–12 %, when height hct ≠ 0 (Fig 1, c) and ratio M/MRd varies between 0,65 and 0,75; 2) The widths of normal cracks in conventional RC beams (subjected to load that corresponds approx. 70 % of their carrying capacity) calculated according to [STR] and [EC] design codes are almost equal to the experimentally obtained crack widths. When beams and slabs are loaded by approximately 52 % of their carrying capacity, design crack widths wk [EC] are approximately 12 % less than wk [STR], although the design crack width wk [RU] is signifi cantly greater. Here, ratio β in the beams and slabs is equal to 2 and 3.3 respectively. Th erefore, the design code [RU] ensures higher probability that the crack width will not reach the limit value (for environmental class XO and XC1) equal in all design codes mentioned in this article; 3) In case of loaded prestressed reinforced concrete beams, the calculated increases of crack widths wk [EC], wk [RU] and w [5] are greater if compared to wk [STR] (Fig 6). Th e increased reinforcement ratio ρ has more signifi cant infl uence on the increases of crack widths calculated according to other design codes if compared to wk [STR]. Tensile concrete above the crack peak has signifi cant infl uence on the design crack width when pre-stressed RC beams are lightly reinforced (ρ ≤ 0,008); 4) During the evaluation of the state of fl exural RC members, expression (5) could be used for calculating the crack width or a position of the neutral axis when the heights of the crack and the tensile zone above the crack are known (calculated or measured experimentally). Design crack widths w (5) are very similar to the experimentally obtained results.
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Swinson, W. F., R. L. Battiste, and G. T. Yahr. "An Experimental Investigation of the Interaction of Primary and Secondary Stresses in Fuel Plates." Journal of Pressure Vessel Technology 119, no. 2 (May 1, 1997): 207–10. http://dx.doi.org/10.1115/1.2842285.
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If the load is not relieved as a structure starts to yield, the induced stress is defined as primary stress. If the load relaxes, as a structure begins to yield the induced stress is defined as secondary stress. In design, it is not uncommon to give more weight to primary stresses than to secondary stresses. However, knowing when this is good design practice and when it is not good design practice represents a problem. In particular, the fuel plates in operating reactors contain both primary stresses and secondary stresses, and to properly assess a design there is a need to assign design weights to the stresses. Tests were conducted on reactor fuel plates intended for the advanced neutron source (ANS) to determine the potential of giving different design weights to the primary and secondary stresses. The results of these tests and the conclusion that the stresses should be weighted the same are given in this paper.
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Widera, G. E. O., Z. F. Sang, and R. Natarajan. "On the Design of Horizontal Pressure Vessels." Journal of Pressure Vessel Technology 110, no. 4 (November 1, 1988): 393–401. http://dx.doi.org/10.1115/1.3265621.
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The objective of this paper is to provide analysis results of displacements and localized stresses in horizontal pressure vessels which were determined by using the three-dimensional finite element method. The analysis models utilized realistic geometry, including saddle supports, vessel heads and actual boundary conditions. The results give a detailed distribution of displacements and local stresses in the saddle support area, and show that the maximum stress is located at the horn of the saddle. A comparison of the results for different saddle locations, (A/L), was performed, and a reasonable location for the supports is suggested. Also, examples of parametric analyses and dimensionless design curves for calculating localized stresses are presented. The latter results should prove to be an invaluable aid in the generation of a new design code for horizontal vessels.
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Martikka, Heikki, and Erkki Taitokari. "Bridge Concept Design Using Heuristic Fuzzy Optimum Design and FEM." Mechanical Engineering Research 3, no. 1 (January 20, 2013): 44. http://dx.doi.org/10.5539/mer.v3n1p44.
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In this study the aim is to present results of bridge concept design using heuristic fuzzy optimum design and FEM. The bridge concept is chosen as the basic suspension type. The deck plate rests on four supports. The middle supports are towers with suspension cables to lift up the bridge plate for minimising its deflection and bending stresses. Mass distribution load and flutter loading act on the plate. Geometric design variables are topology and dimensions of cables and deck. Material variable options are low strength and high strength steel. Decision variables are based on design variables. The main ones are cost and safety factors. The total goal is maximization of the fuzzy satisfaction of the user on all decision variables. The same optimal geometry is obtained for both steel options giving nearly equal performance. The softer steel option is preferable due lower cost. The model and FEM results agree reasonably in stresses and deflections. The fuzzy model used is shown to be an extension of probabilistic models.
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van Driel, W. D., G. Q. Zhang, J. H. J. Janssen, and L. J. Ernst. "Response Surface Modeling for Nonlinear Packaging Stresses." Journal of Electronic Packaging 125, no. 4 (December 1, 2003): 490–97. http://dx.doi.org/10.1115/1.1604149.
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The present study focuses on the development of reliable response surface models (RSM’s) for the major packaging processes of a typical electronic package. The major objective is to optimize the product/process designs against the possible failure mode of vertical die cracks. First, the finite element mode (FEM)-based physics of failure models are developed and the reliability of the predicted stress levels was verified by experiments. In the development of reliable thermo-mechanical simulation models, both the process (time and temperature) dependent material nonlinearity and geometric nonlinearity are taken into account. Afterwards, RSM’s covering the whole specified geometric design spaces are constructed. Finally, these RSM’s are used to predict, evaluate, optimize, and eventually qualify the thermo-mechanical behavior of this electronic package against the actual design requirements prior to major physical prototyping and manufacturing investments.
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Eggert, R. J. "Design Variation Simulation of Thick-walled Cylinders." Journal of Mechanical Design 117, no. 2A (June 1, 1995): 221–28. http://dx.doi.org/10.1115/1.2826126.
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Thick-walled cylinders exposed to high, static internal pressures may experience both elastic and plastic deformation. Primary design considerations include loads, geometry and material properties. However, variations in geometry and material properties due to conventional manufacturing processes, and variations of internal pressure due to actual usage patterns, propagate through the system resulting in off-design stresses and strains which may cause failure. These variations can be evaluated using probabilistic methods which are discussed in this paper. Von Mises-distortion energy yield theory is presented to predict elastic, plastic and residual stresses in thick-walled cylinders. The design variation simulation method using Monte Carlo simulation and available statistical information is used to design a pressure vessel for servo-hydraulic experiments. The use of autofrettage to induce favorable compressive stresses at the inner bore, thereby improving the margin of safety and overall reliability, is also presented.
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Kim, Daehyeon. "Super-single tire loadings and their impacts on pavement design." Canadian Journal of Civil Engineering 35, no. 2 (February 2008): 119–28. http://dx.doi.org/10.1139/l07-090.
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Pavement design and analysis are generally performed based on the load equivalent factor (LEF) obtained from conventional dual tires and assume that the contact stress is equal to the tire inflation pressure. However, heavier tire loadings, such as super-single tires, produce much higher contact stresses than the inflation pressure. This results in larger deformations of subgrades, requiring advanced modeling of subgrades, such as elastic–plastic analysis. Super-single tires also have a different contact area shape from that of conventional tires. To assess the increased contact stresses by super-single tires, realistic contact stress distribution and contact area ratio for super-single tires should be used in the analysis. Three-dimensional finite element analyses of typical flexible pavements were done to evaluate the effects of the increased contact stresses of tire loadings on the subgrades, including load equivalency factors, overlay effect, and subgrade improvement as the behavior of subgrades becomes more important due to the increased contact stresses. Analysis results indicate that the increased contact stresses should be taken into account in the pavement structure design, as well as design of overlay or subgrade improvement. Based on the numerical results, simple design examples are suggested.
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Prevey, P., and N. Jayaraman. "A Design Methodology to Take Credit for Residual Stresses in Fatigue Limited Designs." Journal of ASTM International 2, no. 8 (2005): 12546. http://dx.doi.org/10.1520/jai12546.
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Giannakis, Efstratios, Elli Sivena, Michail Malikoutsakis, and Georgios Savaidis. "Fatigue design and testing of automotive stabilizer bars." MATEC Web of Conferences 188 (2018): 02014. http://dx.doi.org/10.1051/matecconf/201818802014.
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Stabilisers are components of the axle suspension system of cars trucks, trains and other moving road vehicles that connect the movement of the two sides of the suspension (right and left) to keep the vehicle levelled. Stabilizers experience bending and torsion at operation. In particular, their arms experience bending while the main body mainly torsional loading. In both cases, the highly stressed area is the surface, where the maximum tensile and shear stresses are acting. High strength steels and special treatments, thermal and/or mechanical, are used for the stabilisers’ manufacturing. The present study deals with necessary input data for fatigue life assessments based on the FKM guideline [1]. In addition, fatigue tests are conducted to calculate the stress-life curves of two different manufacturing processes.
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Walker, Peter S. "Bearing Surface Design in Total Knee Replacement." Engineering in Medicine 17, no. 4 (October 1988): 149–56. http://dx.doi.org/10.1243/emed_jour_1988_017_041_02.
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Surfaces for condylar total knee replacement are designed using computergraphics techniques. An average anatomical femoral surface is represented mathematically. Mathematical equations are written to describe normal knee motion and normal laxity. Tibial surfaces are generated by placing the femur stepwise in multiple sequential positions, through a defined three-dimensional motion or laxity path. In addition, a flat tibial surface is defined, to represent the least amount of femoral-tibial conformity in currently-used knee replacements. Elasticity theory is used to calculate the maximum contact stresses at the femoral-tibial contact points. The least stresses are produced with a fixed axis cylindrical motion, while the highest are with a flat tibial surface. A surface based on laxity produces lower stresses than for normal knee motion, and is thought to be acceptable in terms of both freedom of motion and stability. Such a laxity surface is proposed as being suitable for total knee design.
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Kosenko, Sergey, Sergey Akimov, and Pavel Surovin. "Technology of rail replacement at end stresses." MATEC Web of Conferences 216 (2018): 01002. http://dx.doi.org/10.1051/matecconf/201821601002.
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The paper focuses on topical issues relating to the maintenance of buffer spans and temporarily repaired sections of continuous welded rail (CWR) tracks. The paper is aimed at developing and studying the feasibility of a technology for replacing temperature-stressed continuous welded rails. For the purposes of this research, the analytical modeling method is used. A design model for moving the end of the stressed rail to the side is presented. Equations of deflections and bending moments arising when the rail is bent to the rated value were derived. Stresses on the rail bending length were determined and compared with the maximum allowable ones. A resource-saving technology has been developed for replacing temperature-stressed buffer rails of a CWR track using intermediate rail fastening Vossloh W-30.
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Woo, Seong-Woo, and Dennis L. O’Neal. "Reliability Design of Mechanical Systems Subject to Repetitive Stresses." Recent Patents on Mechanical Engineering 8, no. 3 (November 11, 2015): 222–34. http://dx.doi.org/10.2174/2212797608666150813001703.
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Woo, Seong-woo, Dennis L. O’Neal, and Yimer Mohammed Hassen. "Reliability design of mechanical systems subjected to repetitive stresses." MATEC Web of Conferences 349 (2021): 03009. http://dx.doi.org/10.1051/matecconf/202134903009.
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To enhance the design of mechanical systems, parametric Accelerated Life Testing (ALT) as a systematic reliability method is proposed as a way to evaluate the design of mechanical systems subjected to repeated impact stresses. It requires: (1) a parametric ALT scheme shaped on system BX lifetime, (2) a load inspection, (3) parametric ALTs with the associated design modifications, and (4) an assessment of whether the revised product design(s) reach the targeted BX life-time. We propose using a general life-stress model and sample size equation. A test example using both market data and parametric ALT was the redesign of a hinge kit system (HKS) in a refrigerator. To conduct parametric ALTs, a force and moment balance analysis was utilized. The mechanical impact loadings of the HKS were evaluated for an working refrigerator door. For the first ALT, the HKS failure happened in the crack/fracture of the kit housing and oil spilled from the damper when the HKS was disassembled. The failure modes and mechanisms constructed in the 1st ALT were similar to those of the unsuccessful samples found from the marketplace. The missing design parameters of the HKS included stress raisers such as corner roundings and the rib of the housing in HKS, the seal in the oil damper, and the material of the cover housing. In the second ALT, the cover housing fractured. The design defect of the cover housing in the HKS was the plastic material. As a corrective action plan, the cover housing was modified from plastic to aluminium. After the second ALT, the lifetime of the modified HKS was reassured to be B1 life 10 years with a yearly failure rate of 0.1%.
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Jeyapalan, Jey K., and B. M. Abdel‐Magid. "Longitudinal Stresses and Strains in Design of RPM Pipes." Journal of Transportation Engineering 113, no. 3 (March 1987): 315–31. http://dx.doi.org/10.1061/(asce)0733-947x(1987)113:3(315).
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Lazăr, Ştefan Marian, and Carmen Răcănel. "Flexible Pavement Design Criterion Based on Octahedral Shear Stresses." Romanian Journal of Transport Infrastructure 6, no. 1 (July 1, 2017): 54–65. http://dx.doi.org/10.1515/rjti-2017-0054.
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Abstract The judicious pavement design is the key factor in achieving the longest service life and the lowest maintenance and rehabilitation costs. It is based on the consideration of the phenomena in which the pavement structures are subjected to exploitation and the limitation of their destructive effects. The aim of this study is to verify the possibility of implementing in the flexible pavement structures design practice of another design criterion based on limiting the bituminous mixtures creep phenomenon and that to be called: The criterion of admissible octahedral shear stresses in the bituminous layers. Estimation of octahedral shear stresses is done with a calculation model based on finite element method, and hereafter referred to as 2D ASFEM (2D Axi-Symmetric Finite Element Model). The paper presents the results obtained by modeling several specific calculation assumptions for the behaviour of flexible pavement structures in service. The study underlines the fact that the Octahedral Shear Stresses Ratio (OSSR) can be an additional design criterion to be taken into account when designing flexible pavement structures alongside other established criteria.
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Majumdar, S. "Transient thermal and dynamic stresses in strongback-design blankets." Fusion Engineering and Design 27, no. 1-2 (March 1, 1995): 430–37. http://dx.doi.org/10.1016/0920-3796(94)00229-z.
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Majumdar, Saurin. "Transient thermal and dynamic stresses in strongback-design blankets." Fusion Engineering and Design 27 (March 1995): 430–37. http://dx.doi.org/10.1016/0920-3796(95)90155-8.
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Park, Jung-Won, and Bong-Jin Yum. "Optimal design of accelerated life tests with two stresses." Naval Research Logistics 43, no. 6 (September 1996): 863–84. http://dx.doi.org/10.1002/(sici)1520-6750(199609)43:6<863::aid-nav5>3.0.co;2-2.
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Goglio, L., M. Rossetto, and E. Dragoni. "Design of adhesive joints based on peak elastic stresses." International Journal of Adhesion and Adhesives 28, no. 8 (December 2008): 427–35. http://dx.doi.org/10.1016/j.ijadhadh.2008.04.001.
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Zhu, Yada, and Elsayed A. Elsayed. "Design of accelerated life testing plans under multiple stresses." Naval Research Logistics (NRL) 60, no. 6 (June 29, 2013): 468–78. http://dx.doi.org/10.1002/nav.21545.
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Porowski, J. S., W. J. O’Donnell, and R. H. Reid. "Weight-Saving Plastic Design of Pressure Vessels." Journal of Pressure Vessel Technology 119, no. 2 (May 1, 1997): 161–66. http://dx.doi.org/10.1115/1.2842278.
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Within the last two decades, the use of elastic finite element analyses to demonstrate design compliance with the rules of the ASME Code has become a generally accepted engineering practice. Linearized stresses from these analyses are commonly used to evaluate primary stresses. For redundant structures or complex structural details, the use of such analyses, instead of simple equilibrium models, often results in significant overconservatism. Direct use of finite element results is often preferred because equilibrium solutions are not unique and effective equilibrium models are not easily constructed for complex three-dimensional structures. However, finite element analyses include secondary stresses, even for pressure, mechanical, and shock loading. For primary stress evaluation, the ASME Code allows the use of inelastic methods based on lower-bound solutions and plastic analysis. For primary stresses, the Code requires equilibrium to be satisfied without violating the yield strength of the material. The use of finite element inelastic analysis to partition mechanically induced stresses into the primary and secondary categories was introduced by Porowski et al. (1993). The latter provides a detailed discussion of the technical approach and the results for the axisymmetric junction between the plate and shell in a pressure vessel. This example was selected by the Session Organizer as a benchmark case to compare the efficiency of various analytical approaches presented at the Session. The authors have since used this approach to design more efficient structures. The practical application of this method to reduce the weight of complex redundant structures designed to meet primary stress limits is described herein for a more complex three-dimensional case. Plastic design utilizes the ability of actual materials to find the most efficient load distribution. A heat exchanger subjected to pressure, accelerations, and nozzle external loads is evaluated as a practical example. The results of elastic analyses are compared with those obtained by inelastic analyses. It is shown that inelastic analyses can be used effectively to reduce the weight of structures using only modern PCs for the engineering computations, as illustrated in this paper.
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Jog, C. S., and S. S. Pande. "Computer-Aided Design of Compact Helical Gear Sets." Journal of Mechanisms, Transmissions, and Automation in Design 111, no. 2 (June 1, 1989): 285–89. http://dx.doi.org/10.1115/1.3258996.
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This paper presents the design strategy for the Computer-Aided Design (CAD) of compact helical gear sets. Using optimization techniques, fundamental gear design parameters such as the number of teeth on the pinion, helix angle, and diametral pitch (or module) are selected subject to constraints on bending stresses, contact stresses, and involute interference limits for both standard and nonstandard gearing. The CAD procedure is illustrated with the help of a design example.
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Chao, Y. J. "Minimum Stress Design of Nozzles in Pressure Vessel Heads." Journal of Pressure Vessel Technology 110, no. 4 (November 1, 1988): 460–63. http://dx.doi.org/10.1115/1.3265630.
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In the early design stage of pressure vessels the configuration of the piping systems is not yet established; hence forces transmitted by the piping systems to the nozzles in the pressure vessels cannot be determined. This often leads to the design of nozzles in pressure vessels guided by consideration of pressure loadings such as the area-replacement method. However, it is true that in many cases the stresses due to external loads can be more critical than those due to the internal pressure. Therefore, engineers often redesign the piping system several times by adding more pipe bends or special restraints for a hot piping system to reduce the reactions at a previously designed nozzle so that the resulting stresses at the nozzle are within the acceptable limit. This paper introduces a rational mechanism whereby the stresses due to the unforeseen external loads can be minimized in the early design stage of the nozzle. An appropriate analysis is discussed which is based on the classical thin shell theory. Analyses using this method allow one to obtain the minimum stresses at a nozzle in a pressure vessel head or a spherical vessel for moment and thrust loadings.
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Tan, Chung Ming, and Mau Yiu Chang. "Stresses Analysis of Hypocycloidal Gear Transmissions." Key Engineering Materials 805 (June 2019): 204–9. http://dx.doi.org/10.4028/www.scientific.net/kem.805.204.
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The objective of this research is to enhance the performance of a Hypocycloidal Gear Transmission (HGT) by selecting the favorable gear profile which has the most significant effects on performance. The research presents computer-aided design and analysis of the HGT. Careful design of the curtate-cycloid tooth profile can further enhance the performance of the HGT by dramatically improving the Hertz contact property. This high contact ratio leads to ideal load distribution. In the loaded tooth contact analysis, the real contact ratio under the tooth deformation was analyzed for demonstration of an effective self-protecting feature, which makes the HGT suitable for extremely heavy load applications. This paper successfully proves that the HGT is a promising architecture for the high reduction ratio reducers. The design and analysis of these prototype HGTs have been fully addressed here.
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Zhang, Bao Sheng, Michael M. Gasik, A. Facchini, M. Pressacco, P. DallaPria, and S. Posocco. "Computer-Integrated Safe Design of FGM Component for Hip Replacement Prosthesis." Materials Science Forum 492-493 (August 2005): 483–88. http://dx.doi.org/10.4028/www.scientific.net/msf.492-493.483.
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Computer-integrated safe design of FGM component for hip replacement prosthesis was presented based on principle of optimal stresses distribution in the FGM component. The goals were to create an FGM structure with reasonable compressive stresses on the surfaces (subjected to wear) and to keep them during the entire manufacturing cycle (sintering, machining, assembling and application). The residual stresses developed in the different parts of the composite were implemented into the subsequent process of the surface grinding and assembly to simulate properly the whole processing route to ensure optimal combination of the processing parameters.
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Suhara, T., K. Yoshida, and T. Yoneya. "Structural Responses and Design Waves of Semisubmersibles." Journal of Offshore Mechanics and Arctic Engineering 111, no. 1 (February 1, 1989): 12–21. http://dx.doi.org/10.1115/1.3257132.
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This paper presents the results of comparative calculations on structural responses of a typical semisubmersible and the discussion on design waves for brace stresses. A typical semisubmersible of two-lowerhull type is adopted as a full-scale model for the comparative calculations on three-dimensional motion and structural responses. Based on the comparative calculations by eight different computer programs, standard response functions are proposed as to axial and bending stresses of major braces. Characteristic wave loading patterns, which correspond to design waves, are proposed based on the standard stress response functions. Also simplified equations of wave forces on semisubmersibles, which are useful to consider design waves, are derived based on the assumptions of taking account of only hydrodynamic inertial forces. Based on these results, maximum brace stresses during a 100-yr return period are estimated using design wave method, and are compared with statistically estimated values by short-term and long-term predictions. As a result, it is found that design wave method has a tentative ground for practical design of semisubmersibles.
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Mufti, A. A., G. Tadros, and A. C. Agarwal. "On the use of finite element programs in structural evaluation and development of design charts." Canadian Journal of Civil Engineering 21, no. 5 (October 1, 1994): 797–804. http://dx.doi.org/10.1139/l94-086.
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In many phases of structural design and analytical evaluation, the solution of stress and strain distribution in an elastic continuum is required. Special cases of such problems may range from two-dimensional plane stress or plain strain distribution, plate bending to analysis of fully three-dimensional solids. The finite element programs are often used to predict the critical regions for stress analysis and design. Stresses are generally of greater practical importance than displacements for structural design and evaluation. Most of the finite element computer programs calculate element stresses at the centroids, integration points, or nodes of elements. In this paper, examples of bridge deck analysis are used to illustrate the stress interpretation using the finite element programs. It is demonstrated that the stresses at nodes calculated by some finite element programs violate the equilibrium conditions and do not converge to the correct answers. These calculated stresses at nodes are usually too low and lead to unsafe designs and evaluations. Key words: finite element method, finite element programs, structural analysis, least square smoothing, stress interpolation.
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STOYTCHEV, S., G. PALLOTTI, and P. PETTAZZONI. "OPTIMAL DESIGN OF ARTERIAL BYPASS PROSTHESES DIAMETER." Journal of Mechanics in Medicine and Biology 01, no. 02 (October 2001): 107–22. http://dx.doi.org/10.1142/s0219519401000222.
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The objectives of this paper are: (1) to analyze how the bypass diameter and the degree of the stenosis affect the flow-induced wall shear stresses in the stenotic and bypass vessels and (2) to propose a clinically usable method for a proper selection of the bypass diameter. The problem is solved in the following stages: First, the steady pressure and flow within the vessels are obtained using general laws of mass and energy conservation. Then, on the basis of modified Womersley's theory to take into account the nonlinear mechanical properties of the vessels, the oscillating pressure and flow within the vessels are calculated. They are used to derive expressions for the reflection coefficients at the distal (converging) bifurcation and to calculate wall shear stresses. We hypothesize that the minimal differences in the wall shear stresses of the normal artery, stenotic artery and the bypass graft mitigate the development of anastomotic neointimal hyperplasia and graft pseudo intima. Using cost functions, based on steady and mean wall shear stresses, we calculated the optimal value of the undeformed bypass diameter for various degrees of stenosis. We found that the sum of cross-sectional areas of the optimal graft and the stenotic artery (normalized with respect to the cross-sectional area of the normal artery) varies between 1.14 and 1.28, an interval, which is consistent with the findings of McDonald (1974) for the area of the major branches in the body. Thus we conclude that the results obtained are consistent with the stated hypothesis.
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Korcz-Konkol, Natalia, and Piotr Iwicki. "Corrugated Sheeting as a Member of a Shear Panel Under Repeated Load—Experimental Test." Materials 13, no. 18 (September 11, 2020): 4032. http://dx.doi.org/10.3390/ma13184032.
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In stressed-skin design, the cladding stiffening effect on structures is taken into account. However, the “traditional” design is more usual, wherein this effect is neglected. Even if the diaphragm actions are not regarded, in particular cases such as big sheds (and others), the parasitic (unwanted) stressed-skin action may occur with the result of leakage or even failure. The structures of this kind have already been built. Thus, an important question arises: How can one assess them if there is a need to correct or redesign them? What kind of non-destructive approach can be used to achieve that? Experimental tests of small-scale shear panels made of trapezoidal sheeting were designed in order to observe the behaviour of the diaphragm under increasing and repeated load. The tests were oriented toward force–displacement relations and strains in selected areas of the sheeting. The results revealed nonlinear, hysteretic force–displacement behaviour of the panel and the occurrence of the persistent deflections and stresses which remain even after the unloading. The relation among the stresses, force–displacement paths and modes of failure can be potentially used in monitoring systems of existing buildings in terms of parasitic stressed-skin action.
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Savchenko, Kyrylo, Anatoliy Zinkovskii, Romuald Rzadkowski, Radoslaw Przysowa, and Vadym Kruts. "An influence of shroud design parameters on the static stresses of blade assemblies." MATEC Web of Conferences 304 (2019): 03002. http://dx.doi.org/10.1051/matecconf/201930403002.
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In this study, the structural analysis of the blade assemblies was carried out using the finite element method to determine the influence of design parameters of shroud couplings on the static stresses of turbine rotor blades with zigzag and slant shroud couplings. An angle of inclination of the shroud contact surfaces with respect to the rotor rotation axis was selected as the design parameter. Based on the calculation results, it has been found that irrespective of the type of the shroud coupling, the values of the contact pressure and the stresses in the shroud increase with the angle of inclination of the contact surfaces. Also, for the slant shroud coupling, the stresses increase in the blade airfoil portion with the increase of angle of inclination of the contact surfaces, while for the zigzag shroud coupling the contact stresses decrease with the increase of this angle. It was concluded that the zigzag shroud coupling causes the increase in static stresses when compared to the slant one.
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Lennon, A. B., and P. J. Prendergast. "Evaluation of Cement Stresses in Finite Element Analyses of Cemented Orthopaedic Implants." Journal of Biomechanical Engineering 123, no. 6 (July 10, 2001): 623–28. http://dx.doi.org/10.1115/1.1412452.
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Stress analysis of the cement fixation of orthopaedic implants to bone is frequently carried out using finite element analysis. However, the stress distribution in the cement layer is usually intricate, and it is difficult to report it in a way that facilitates comparison of implants for pre-clinical testing. To study this problem, and make recommendations for stress reporting, a finite element analysis of a hip prosthesis implanted into a synthetic composite femur is developed. Three cases are analyzed: a fully bonded implant, a debonded implant, and a debonded implant where the cement is removed distal to the stem tip. In addition to peak stresses, and contour and vector plots, a stressed volume and probability-of-failure analysis is reported. It is predicted that the peak stress is highest for the debonded stem, and that removal of the distal cement more than halves this peak stress. This would suggest that omission of the distal cement is good for polished prostheses (as practiced for the Exeter design). However, if the percentage of cement stressed above a certain threshold (say 3 MPa) is considered, then the removal of distal cement is shown to be disadvantageous because a higher volume of cement is stressed to above the threshold. Vector plots clearly demonstrate the different load transfer for bonded and debonded prostheses: A bonded stem generates maximum tensile stresses in the longitudinal direction, whereas a debonded stem generates most tensile stresses in the hoop direction, except near the tip where tensile longitudinal stresses occur due to subsidence of the stem. Removal of the cement distal to the tip allows greater subsidence but alleviates these large stresses at the tip, albeit at the expense of increased hoop stresses throughout the mantle. It is concluded that a thorough analysis of cemented implants should not report peak stress, which can be misleading, but rather stressed volume, and that vector plots should be reported if a precise analysis of the load transfer mechanism is required.
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CHONG, DESMOND Y. R., ULRICH N. HANSEN, and ANDREW A. AMIS. "THE INFLUENCE OF TIBIAL PROSTHESIS DESIGN FEATURES ON STRESSES RELATED TO ASEPTIC LOOSENING AND STRESS SHIELDING." Journal of Mechanics in Medicine and Biology 11, no. 01 (March 2011): 55–72. http://dx.doi.org/10.1142/s0219519410003666.
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Aseptic loosening caused by mechanical factors is a recognized failure mode for tibial components of knee prostheses. This parametric study investigated the effects of prosthesis fixation design changes, which included the presence, length and diameter of a central stem, the use of fixation pegs beneath the tray, all-polyethylene versus metal-backed tray, prosthesis material stiffness, and cement mantle thickness. The cancellous bone compressive stresses and bone–cement interfacial shear stresses, plus the reduction of strain energy density in the epiphyseal cancellous bone, an indication of the likelihood of component loosening, and bone resorption secondary to stress shielding, were examined. Design features such as longer stems reduced bone and bone–cement interfacial stresses thus the risk of loosening is potentially minimized, but at the expense of an increased tendency for bone resorption. The conflicting trend suggested that bone quality and fixation stability have to be considered mutually for the optimization of prosthesis designs. By comparing the bone stresses and bone–cement shear stresses to reported fatigue strength, it was noted that fatigue of both the cancellous bone and bone–cement interface could be the driving factor for long-term aseptic loosening for metal-backed tibial trays.
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Dapino, Marcelo J., and Phillip G. Evans. "Constitutive Modeling for Design and Control of Magnetostrictive Galfenol Devices." Advances in Science and Technology 54 (September 2008): 13–18. http://dx.doi.org/10.4028/www.scientific.net/ast.54.13.
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A dynamic, nonlinear model for magnetic induction and strain response of cubic magnetostrictive materials to 3-D dynamic magnetic fields and 3-D stresses is developed. Dynamic eddy current losses and inertial stresses are modeled by coupling Maxwell’s equations to Newton’s second law through a nonlinear constitutive model. The constitutive model is derived from continuum thermodynamics.
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Sorem, J. R., J. R. Shadley, and S. M. Tipton. "Design Curves for Maximum Stresses in Blocks Containing Pressurized Bore Intersections." Journal of Mechanical Design 113, no. 4 (December 1, 1991): 427–31. http://dx.doi.org/10.1115/1.2912800.
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Intersecting bore geometries are used in a number of industrial applications such as in fluid ends of reciprocating pumps. Maximum tensile stresses at stress concentration points in the block can be many times the fluid pressure in the bores. Obtaining good estimates of the maximum stresses in the structure is necessary for making sound design decisions on the block dimensions. Finite element models of the bore intersection geometry were analyzed for ranges of bore sizes and block dimensions. Results of the finite element model were compared with predictions provided by a popular approximation method based on mechanics of materials principles. The approximation method was found to underpredict the maximum stresses in the block in almost every case analyzed. For some conditions, the maximum stresses computed from the finite element model were more than two times the predictions provided by the approximation method. Design curves, based on the ratio of the sizes of the intersecting bores, are presented for selecting block dimensions to meet desired maximum stress criteria.
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Fermér, M. "Optimization of a Railway Freight Car Wheel by Use of a Fractional Factorial Design Method." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 208, no. 2 (July 1994): 97–107. http://dx.doi.org/10.1243/pime_proc_1994_208_239_02.
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The performance of a ‘low-stress wheel’ exposed to vertical and lateral contact forces and to thermal braking loads is investigated. Based on finite element calculations, a two-level fractional factorial design method is used to quantify the influences of rim thickness, disc thickness and hub-rim offset on thermal and mechanical stressses, on axial rim displacement, and on wheel mass. A number of approximating linear empirical formulas have been obtained. They offer a powerful tool in designing and optimizing railway wheels. The most effective measure to reduce thermal and mechanical stresses is found to be a hub-rim offset but the penalty is a thermoelastic axial rim displacement during heating. This displacement can be minimized by using as large an offset as possible within geometrical limits. In contrast to the standard type of wheel, no residual deformations and large stresses are induced in the offset wheel after heavy block braking. Full-scale dynamometer brake tests performed on a new prototype wheel are reported. The test results support the calculation model used.
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Osakue, Edward E., and Lucky Anetor. "Design of Elastic Screw Fasteners under Tensile Load." Mechanical Engineering Research 7, no. 1 (May 31, 2017): 13. http://dx.doi.org/10.5539/mer.v7n1p13.
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This paper presents an equivalent stress approach in the design of screw fasteners under tensile load. Design equations are formulated for sizing and verifying screw fastener selection. It considers axial tensile, direct shear, bending, and torsional stresses and combines them as appropriate into equivalent or effective stresses. The equivalent or effective stresses are compared with screw fastener material strength capabilities such as proof, yield, fatigue, and tensile strengths for failure assessment. Design factors are derived for assessing design adequacy the screw fastener. For elastic screw fasteners, these stresses must each be in the elastic range for the screw material. When the load is removed, elastic screw fasteners regain their original size and shape, behaving like springs. Two illustrative design examples are used to demonstrate both design verification and sizing tasks. Design verification was performed in the first example and the static yield design factors are found to be 0.77 and 0.68 for the preload and service load, respectively. These values are less than unity, representing a case of under-design in static yield failure modes. Without changing the specification of the screw fastener, the preload tension was reduced by 62.76%, and the static yield design factors changed to 1.42 and 1.12 for the preload and service load, respectively. This shows that the under-design condition resulted from high preload tension. When the screw pitch is changed from coarse to fine series, the design factors are worse off in fatigue stress resistance but indicated some improvement in static stress resistance. This suggests that fine pitch threads is not better than coarse pitch threads in fatigue stress capacity when direct shear and bending stresses are considered in Example 1. Both design sizing and verification are performed in Example 2. Design sizing suggests a screw fastener ( ) of slightly larger size than the previous solution ( ). Design verification indicates the previous solution and new solution has a minimum static yield design factor of 0.93 and 1.09, respectively for the service load. This suggests that the screw fastener of the previous solution may yield in service, if implemented. The new solution has a higher design factor in this failure mode and presents less risk of failure. From the illustrative examples presented, it seems that ignoring direct and bending stresses in screw fastener design can lead to under-design in some failure modes.
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Jinescu, Valeriu. "Fatigue life prediction for simultaneous cyclic loading with blocks of normal stresses and shear stresses." Journal of Engineering Sciences and Innovation 1, no. 1 (August 30, 2016): 1–16. http://dx.doi.org/10.56958/jesi.2016.1.1.1.
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The problem of effects superposition in the case of simultaneous loadings, an important issue in mechanical structures design, have been analised. A method for the multiaxial fatigue life prediction was developed. This method was applied to fatigue life calculation in the cases of cyclical loading with: – one block of normal stress and one bloc of shear stress; – successive blocks of normal stresses, simultaneous with successive blocks of shear stresses. The influence of deterioration, of mean stress and residual stress upon the fatigue life is introduced. The theoretical results: – have been compared with experimental results reported in literature; – may be used for design, as well as for experimental data evaluation. Numerical examples show how the obtained theoretical results may be used in practical cases.