scholarly journals The Influence of the Honeycomb Design Parameters on the Mechanical Behavior of Non-Pneumatic Tires

2020 ◽  
Vol 12 (03) ◽  
pp. 2050024
Author(s):  
Evangelia Ganniari-Papageorgiou ◽  
Panagiotis Chatzistergos ◽  
Xiaoxu Wang
Keyword(s):  
Mechanical Behavior ◽  
Contact Pressure ◽  
Cell Length ◽  
Design Parameters ◽  
Internal Stresses ◽  
Geometrical Parameters ◽  
Vertical Stiffness ◽  
Vertical Loading ◽  
Wide Range ◽  
Pneumatic Tires

Non-Pneumatic Tires with honeycomb structure have complex design and their mechanical behavior is influenced by their geometry. As a result, deep understanding of the effect of various design parameters is very important for design optimization. In this numerical analysis, the effect of a wide range of internal geometrical parameters on the tire’s weight and mechanical behavior was quantified. For this purpose, a parametric finite element model was designed and subjected to vertical loading to assess its maximum stress, contact pressure, maximum vertical displacement and energy absorbed during loading. The analysis indicated that vertical stiffness is strongly affected by the density, thickness and internal angles of the honeycomb cells. The internal angles of the honeycomb also appeared capable of changing the tire’s vertical stiffness without changing its weight, which is associated with the tire’s fuel efficiency and dynamic properties. A decrease in cell length or an increase in cell density was capable of significantly reducing the internal stresses. Proper tuning of cell thickness or cell length could also significantly reduce the magnitude of contact pressure developed by producing a more even distribution of loading between the tread and the road.

Genetic Optimization of Geometrical Parameters of High Speed Rotor

2015 ◽  
Author(s):  
Behnam Ghalamchi ◽  
Adam Kłodowski ◽  
Jussi T. Sopanen ◽  
Aki M. Mikkola
Keyword(s):  
High Speed ◽  
Turbine Rotor ◽  
Optimization Techniques ◽  
Design Parameters ◽  
Geometrical Parameters ◽  
Campbell Diagram ◽  
Critical Speeds ◽  
Operation Speed ◽  
Wide Range ◽  
Speed Range

The main scope of this paper is optimization of high speed rotor systems by using Evolutionary Algorithm. The target of the optimization is finding geometrical parameters of the shaft, in such a way that the critical speeds are not occurring in the operation speed range. Rotating machines have a wide range of applications in industrial machinery and applying numerical optimization techniques helps engineers to improve the performance of rotor bearing systems. A schematic of a turbine rotor system is studied. The rotor is modeled using finite element method and Timoshenko beam elements having four degrees of freedom (DOF) per node — two translational and two rotational. Critical speeds are identified using Campbell diagram. The outcome of the simulation is looking to find the widest safe margin for operation speed range without any critical speed in Campbell diagram within the operation range. Design parameters for optimization are overhang shafts lengths and diameters. Several simulation runs with different variables shows a significant effect of these parameters in dynamic behavior of the system. Comparison of the results with the basic design of turbine rotor reveals that all constraints are satisfied.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

Theoretical study of the prestressing strand's stress by computer modeling methods

2020 ◽  
Vol 76 (11) ◽  
pp. 1139-1148
Author(s):  
A. G. Korchunov ◽  
E. M. Medvedeva ◽  
E. M. Golubchik
Keyword(s):  
Residual Stresses ◽  
High Strength ◽  
Pearlitic Steel ◽  
Internal Stresses ◽  
Steel Microstructure ◽  
Compressive Stresses ◽  
Wide Range ◽  
Prestressing Strands ◽  
Increasing Temperature ◽  
Wire Strand

The modern construction industry widely uses reinforced concrete structures, where high-strength prestressing strands are used. Key parameters determining strength and relaxation resistance are a steel microstructure and internal stresses. The aim of the work was a computer research of a stage-by-stage formation of internal stresses during production of prestressing strands of structure 1х7(1+6), 12.5 mm diameter, 1770 MPa strength grade, made of pearlitic steel, as well as study of various modes of mechanical and thermal treatment (MTT) influence on their distribution. To study the effect of every strand manufacturing operation on internal stresses of its wires, the authors developed three models: stranding and reducing a 7-wire strand; straightening of a laid strand, stranding and MTT of a 7-wire strand. It was shown that absolute values of residual stresses and their distribution in a wire used for strands of a specified structure significantly influence performance properties of strands. The use of MTT makes it possible to control in a wide range a redistribution of residual stresses in steel resulting from drawing and strand laying processes. It was established that during drawing of up to 80% degree, compressive stresses of 1100-1200 MPa degree are generated in the central layers of wire. The residual stresses on the wire surface accounted for 450-500 MPa and were tension in nature. The tension within a range of 70 kN to 82 kN combined with a temperature range of 360-380°С contributes to a two-fold decrease in residual stresses both in the central and surface layers of wire. When increasing temperature up to 400°С and maintaining the tension, it is possible to achieve maximum balance of residual stresses. Stranding stresses, whose high values entail failure of lay length and geometry of the studied strand may be fully eliminated only at tension of 82 kN and temperature of 400°С. Otherwise, stranding stresses result in opening of strands.

scholarly journals Hydromechanics of low-Reynolds-number flow. Part 2. Singularity method for Stokes flows

1975 ◽  
Vol 67 (4) ◽  
pp. 787-815 ◽  
Author(s):  
Allen T. Chwang ◽  
T. Yao-Tsu Wu
Keyword(s):  
Exact Solutions ◽  
Stokes Flow ◽  
Fundamental Solutions ◽  
The Body ◽  
Circular Cylinders ◽  
Geometrical Parameters ◽  
Flow Problems ◽  
Singularity Method ◽  
Wide Range ◽  
Body Shapes

The present study further explores the fundamental singular solutions for Stokes flow that can be useful for constructing solutions over a wide range of free-stream profiles and body shapes. The primary singularity is the Stokeslet, which is associated with a singular point force embedded in a Stokes flow. From its derivatives other fundamental singularities can be obtained, including rotlets, stresslets, potential doublets and higher-order poles derived from them. For treating interior Stokes-flow problems new fundamental solutions are introduced; they include the Stokeson and its derivatives, called the roton and stresson.These fundamental singularities are employed here to construct exact solutions to a number of exterior and interior Stokes-flow problems for several specific body shapes translating and rotating in a viscous fluid which may itself be providing a primary flow. The different primary flows considered here include the uniform stream, shear flows, parabolic profiles and extensional flows (hyper-bolic profiles), while the body shapes cover prolate spheroids, spheres and circular cylinders. The salient features of these exact solutions (all obtained in closed form) regarding the types of singularities required for the construction of a solution in each specific case, their distribution densities and the range of validity of the solution, which may depend on the characteristic Reynolds numbers and governing geometrical parameters, are discussed.

scholarly journals A Two-Round Optimization Design Method for Aerostatic Spindles Considering the Fluid–Structure Interaction Effect

2021 ◽  
Vol 11 (7) ◽  
pp. 3017
Author(s):  
Qiang Gao ◽  
Siyu Gao ◽  
Lihua Lu ◽  
Min Zhu ◽  
Feihu Zhang
Keyword(s):  
Optimal Design ◽  
Optimization Design ◽  
Design Method ◽  
Fluid Structure Interaction ◽  
Design Procedure ◽  
Design Parameters ◽  
Geometrical Parameters ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Aerostatic Spindle

The fluid–structure interaction (FSI) effect has a significant impact on the static and dynamic performance of aerostatic spindles, which should be fully considered when developing a new product. To enhance the overall performance of aerostatic spindles, a two-round optimization design method for aerostatic spindles considering the FSI effect is proposed in this article. An aerostatic spindle is optimized to elaborate the design procedure of the proposed method. In the first-round design, the geometrical parameters of the aerostatic bearing were optimized to improve its stiffness. Then, the key structural dimension of the aerostatic spindle is optimized in the second-round design to improve the natural frequency of the spindle. Finally, optimal design parameters are acquired and experimentally verified. This research guides the optimal design of aerostatic spindles considering the FSI effect.

scholarly journals Multi-stable composite twisting structure for morphing applications

2012 ◽  
Vol 468 (2141) ◽  
pp. 1230-1251 ◽  
Author(s):  
X. Lachenal ◽  
P. M. Weaver ◽  
S. Daynes
Keyword(s):  
Analytical Model ◽  
Material Properties ◽  
Degrees Of Freedom ◽  
Design Parameters ◽  
Engineering Structures ◽  
The Past ◽  
Wide Range ◽  
Morphing Structure ◽  
Low Mass ◽  
Unstable States

Conventional shape-changing engineering structures use discrete parts articulated around a number of linkages. Each part carries the loads, and the articulations provide the degrees of freedom of the system, leading to heavy and complex mechanisms. Consequently, there has been increased interest in morphing structures over the past decade owing to their potential to combine the conflicting requirements of strength, flexibility and low mass. This article presents a novel type of morphing structure capable of large deformations, simply consisting of two pre-stressed flanges joined to introduce two stable configurations. The bistability is analysed through a simple analytical model, predicting the positions of the stable and unstable states for different design parameters and material properties. Good correlation is found between experimental results, finite-element modelling and predictions from the analytical model for one particular example. A wide range of design parameters and material properties is also analytically investigated, yielding a remarkable structure with zero stiffness along the twisting axis.

Local Hydrostatic Pressure Test for Cylindrical Vessels

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
H. Al-Gahtani ◽  
A. Khathlan ◽  
M. Sunar ◽  
M. Naffa'a
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Hydrostatic Pressure ◽  
Cylindrical Vessel ◽  
Geometrical Parameters ◽  
The Finite Element Method ◽  
Wide Range ◽  
Pressure Test ◽  
Local Test ◽  
Alternative Test

The juncture of a small cylindrical nozzle to a large cylindrical vessel is very common in the pressure vessel industry. Upon fabrication, it is required that the whole structure is subjected to pressure testing. The test can be expensive as it necessitates pressurizing the whole structure typically having a large volume. Hence, it is proposed to make a “local test,” which is considerably simpler as it involves capping the small nozzle and testing only a relatively small portion of the structure. This paper investigates the accuracy and reliability of such an alternative test, using the finite-element method. Two different finite-element types are used in the study, specifically a shell-based element and a solid-based element. The verification of the finite-element results for two different cases shows that the models used in the study are valid. It also proves that the two element types yield very similar stress results. In addition, the study includes a numerical investigation of more than 40 different nozzle-to-vessel junctures with a wide range of parameters for the nozzle and vessel. The results indicate that the use of cylindrical caps that are slightly larger than the nozzle is not recommended as it produces stresses that are significantly different from those for the original required pressure test. As such, the study provides an estimate of the smallest size of the cap that may be used in the local test to generate stresses that agree with the full test. For most practical geometries, it is shown that the size of the cap needs to be at least 2–30 times larger than that of the nozzle, depending on the geometrical parameters of the juncture.

Closed-Form Correlation of Buildings Energy Use With Key Design Parameters Calibrated Using a Genetic Algorithm

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Raed I. Bourisli ◽  
Adnan A. AlAnzi
Keyword(s):  
Genetic Algorithm ◽  
Closed Form ◽  
Energy Use ◽  
Building Design ◽  
Office Buildings ◽  
Design Parameters ◽  
Wide Range ◽  
Variable Function ◽  
Real Coded Genetic Algorithm ◽  
The Difference

This work aims at developing a closed-form correlation between key building design variables and its energy use. The results can be utilized during the initial design stages to assess the different building shapes and designs according to their expected energy use. Prototypical, 20-floor office buildings were used. The relative compactness, footprint area, projection factor, and window-to-wall ratio were changed and the resulting buildings performances were simulated. In total, 729 different office buildings were developed and simulated in order to provide the training cases for optimizing the correlation’s coefficients. Simulations were done using the VisualDOE TM software with a Typical Meteorological Year data file, Kuwait City, Kuwait. A real-coded genetic algorithm (GA) was used to optimize the coefficients of a proposed function that relates the energy use of a building to its four key parameters. The figure of merit was the difference in the ratio of the annual energy use of a building normalized by that of a reference building. The objective was to minimize the difference between the simulated results and the four-variable function trying to predict them. Results show that the real-coded GA was able to come up with a function that estimates the thermal performance of a proposed design with an accuracy of around 96%, based on the number of buildings tested. The goodness of fit, roughly represented by R2, ranged from 0.950 to 0.994. In terms of the effects of the various parameters, the area was found to have the smallest role among the design parameters. It was also found that the accuracy of the function suffers the most when high window-to-wall ratios are combined with low projection factors. In such cases, the energy use develops a potential optimum compactness. The proposed function (and methodology) will be a great tool for designers to inexpensively explore a wide range of alternatives and assess them in terms of their energy use efficiency. It will also be of great use to municipality officials and building codes authors.

Application areas of the angle reflector

2021 ◽  
pp. 54-59
Author(s):  
L. R. Yurenkova ◽  
O. A. Yakovuk ◽  
I. V. Morozov
Keyword(s):  
Radio Wave ◽  
Outer Space ◽  
Road Transport ◽  
Optical Systems ◽  
Design Parameters ◽  
Design Activity ◽  
Primary Role ◽  
Beam Laser ◽  
Wide Range ◽  
Graphical Calculation

The article provides examples of how the device known as the «angle reflector» a few decades ago has been increasingly used in various fields of science and technology in recent years. Angle reflectors are designed to change (reflect) optical and radar rays in the direction, opposite to the original direction. At present, angle reflectors are widely used to ensure the safety of road transport on dangerous road sections. Radio wave reflectors have the same design as optical ones; therefore, in radio detection and location, angle reflectors are used to send warning signals to ship radars on bridge supports, beacons and buoys. Modern angle reflectors attached to meteorological probes allow determining the direction and speed of the wind at high altitude, which is especially important in the study of the outer space. In recent years, devices have been developed to improve the accuracy of radar stations calibration. The examples of graphical calculation of angle reflectors presented in the article clearly demonstrate the primary role of geometry in the design activity of an engineer. The graphical calculation is based on the theoretical positions of projective geometry. The design and calculation of optical systems is carried out by the graphoanalytic method, since only with a combination of graphical and analytical methods it is possible to accurately calculate the course of a light beam, laser, or radio wave and thereby determine the design parameters of the devices. The article focuses on a graphical method for calculating two types of angle reflectors using orthogonal projection, due to which modern engineers will be able to create more up-to-date designs of optical systems with a wide range of applications.

Airbag Inflators

1999 ◽  
Author(s):  
William G. Broadhead ◽  
D. Theodore Zinke
Keyword(s):  
High Speed ◽  
Motor Vehicle ◽  
Seat Belt ◽  
Design Parameters ◽  
Steering Wheel ◽  
Instrument Panel ◽  
Highway Traffic ◽  
National Highway Traffic Safety ◽  
Column Collapse ◽  
Wide Range

Abstract The design of an airbag restraint system presents a classic engineering challenge. There are numerous design parameters that need to be optimized to cover the wide range of occupant sizes, occupant positions and vehicle collision modes. Some of the major parameters that affect airbag performance include, the airbag inflator characteristics, airbag size and shape, airbag vent size, steering column collapse characteristics, airbag cover characteristics, airbag fold pattern, knee bolsters, seat, seat belt characteristics, and vehicle crush characteristics. Optimization of these parameters can involve extremely costly programs of sled tests and full scale vehicle crash tests. Federal Motor Vehicle Safety Standards (FMVSS) with regard to airbag design are not specific and allow flexibility in component characteristics. One design strategy, which is simplistic and inexpensive, is to utilize a very fast, high output gas generator (inflator). This ensures that the bag will begin restraining the occupant soon after deployment and can make up for deficiencies in other components such as inadequate steering column collapse or an unusually stiff vehicle crush characteristic. The use of such inflators generally works well for properly positioned occupants in moderate to high-speed frontal collisions by taking advantage of the principle of ridedown. When an airbag quickly fills the gap between the occupant and the instrument panel or steering wheel it links him to the vehicle such that he utilizes the vehicle’s front-end crush to help dissipate his energy, thus reducing the restraint forces. Unfortunately, powerful airbag systems can be injurious to anyone in the path of the deploying airbag. This hazard is present for short statured individuals, out of position children or any occupant in a collision that results in extra ordinary crash sensing time. Currently, the National Highway Traffic Safety Administration (NHTSA) is proposing to rewrite FMVSS 208 to help reduce such hazards.

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