Pavement Damage Due to Conventional and New Generation of Wide-Base Super Single Tires

2005 ◽  
Vol 33 (4) ◽  
pp. 210-226 ◽  
Author(s):  
I. L. Al-Qadi ◽  
M. A. Elseifi ◽  
P. J. Yoo ◽  
I. Janajreh
Keyword(s):  
Carrying Capacity ◽  
Material Properties ◽  
Three Dimensional ◽  
Fe Analysis ◽  
Load Carrying Capacity ◽  
Inflation Pressure ◽  
3D Finite Element ◽  
Load Carrying ◽  
Pavement Damage ◽  
New Generation

Abstract The objective of this study was to quantify pavement damage due to a conventional (385/65R22.5) and a new generation of wide-base (445/50R22.5) tires using three-dimensional (3D) finite element (FE) analysis. The investigated new generation of wide-base tires has wider treads and greater load-carrying capacity than the conventional wide-base tire. In addition, the contact patch is less sensitive to loading and is especially designed to operate at 690kPa inflation pressure at 121km/hr speed for full load of 151kN tandem axle. The developed FE models simulated the tread sizes and applicable contact pressure for each tread and utilized laboratory-measured pavement material properties. In addition, the models were calibrated and properly validated using field-measured stresses and strains. Comparison was established between the two wide-base tire types and the dual-tire assembly. Results indicated that the 445/50R22.5 wide-base tire would cause more fatigue damage, approximately the same rutting damage and less surface-initiated top-down cracking than the conventional dual-tire assembly. On the other hand, the conventional 385/65R22.5 wide-base tire, which was introduced more than two decades ago, caused the most damage.

Variational Method for Limit Load Analysis of Inhomogeneous Media

2009 ◽  
Author(s):  
R. Adibi-Asl ◽  
R. Seshadri
Keyword(s):  
Carrying Capacity ◽  
Material Properties ◽  
Three Dimensional ◽  
Limit Load ◽  
Load Carrying Capacity ◽  
Element Analysis ◽  
Strain Fields ◽  
Adjustment Procedure ◽  
Load Carrying ◽  
Load Analysis

The load carrying capacity of a body with varying material properties (inhomogeneous) is investigated using the various lower and upper bound limit load multipliers in the context of varational principles originally proposed by Mura and co-workers. In order to evaluate the different limit load multipliers, Elastic Modulus Adjustment Procedure (EMAP) is used to obtain statically admissible stress and kinemattically admissible strain fields at a limit load stage. The proposed upper and lower bound limit load solutions are compared with the results obtained from inelastic finite element analysis (FEA) for several examples with two-dimensional and three-dimensional geometries.

Influence of hard rolling and the cooling lubricant on the material properties and the rolling strength of PM gears

2019 ◽  
Vol 71 (3) ◽  
pp. 406-410
Author(s):  
Fritz Klocke ◽  
Thomas Bergs ◽  
Christoph Löpenhaus ◽  
Philipp Scholzen ◽  
Tim Frech
Keyword(s):  
Boundary Layer ◽  
Carrying Capacity ◽  
Material Properties ◽  
Rolling Process ◽  
Surface Zone ◽  
Load Carrying Capacity ◽  
Content Type ◽  
Load Carrying ◽  
Phosphorous Content ◽  
Cooling Lubricant

Purpose The lower density of powder metallurgical (PM) gears compared to solid steel gears leads to not only a lower weight but also a lower load-carrying capacity. Therefore, PM gears are cold rolled before hardening to increase the density in the highly stressed surface zone and, thus, the flank load-carrying capacity. A further approach to increase the flank load-carrying capacity is the reduction of friction and wear in the tooth contact. The purpose of this paper is to analyze the hard rolling process as a new manufacturing step in the PM process chain to influence the boundary layer. Design/methodology/approach The investigation includes the new process of hard rolling, the variation of the cooling lubricant in the hard rolling process and the evaluation of its influence on the material properties and the flank load-carrying capacity. Therefore, the additives of the cooling lubricant are varied regarding the sulfur and phosphorous content. The load-carrying capacity is evaluated on disk-on-disk test rig and the material properties are evaluated by metallographic tests and boundary layer. Findings The results of the specimen characteristics in the micro and nano range show a significant influence of hard rolling on the residual stresses and the chemical surface composition. Because of hard rolling, residual compressive stresses as well as roughness are reduced and the flank load-carrying capacity is increased by high phosphorous content of the cooling lubricant. Originality/value This paper investigates a new manufacturing step to increase resource efficiency by increasing the flank load-carrying capacity of spur gears.

Geometry Optimization of Textured Three-Dimensional Micro- Thrust Bearings

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
C. I. Papadopoulos ◽  
E. E. Efstathiou ◽  
P. G. Nikolakopoulos ◽  
L. Kaiktsis
Keyword(s):  
Carrying Capacity ◽  
Stokes Equations ◽  
Load Capacity ◽  
Three Dimensional ◽  
Load Carrying Capacity ◽  
Thrust Bearings ◽  
Micro Channels ◽  
Wide Range ◽  
Load Carrying ◽  
Bearing Load

This paper presents an optimization study of the geometry of three-dimensional micro-thrust bearings in a wide range of convergence ratios. The optimization goal is the maximization of the bearing load carrying capacity. The bearings are modeled as micro-channels, consisting of a smooth moving wall (rotor), and a stationary wall (stator) with partial periodic rectangular texturing. The flow field is calculated from the numerical solution of the Navier-Stokes equations for incompressible isothermal flow; processing of the results yields the bearing load capacity and friction coefficient. The geometry of the textured channel is defined parametrically for several width-to-length ratios. Optimal texturing geometries are obtained by utilizing an optimization tool based on genetic algorithms, which is coupled to the CFD code. Here, the design variables define the bearing geometry and convergence ratio. To minimize the computational cost, a multi-objective approach is proposed, consisting in the simultaneous maximization of the load carrying capacity and minimization of the bearing convergence ratio. The optimal solutions, identified based on the concept of Pareto dominance, are equivalent to those of single-objective optimization problems for different convergence ratio values. The present results demonstrate that the characteristics of the optimal texturing patterns depend strongly on both the convergence ratio and the width-to-length ratio. Further, the optimal load carrying capacity increases at increasing convergence ratio, up to an optimal value, identified by the optimization procedure. Finally, proper surface texturing provides substantial load carrying capacity even for parallel or slightly diverging bearings. Based on the present results, we propose simple formulas for the design of textured micro-thrust bearings.

Structural Kinematics of Partially-Parallel Robotic Mechanisms

1987 ◽  
Author(s):  
M. Gaber Mohamed
Keyword(s):  
Carrying Capacity ◽  
Kinematic Chain ◽  
Performance Criteria ◽  
Load Carrying Capacity ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Load Carrying ◽  
Parallel Kinematic ◽  
New Generation ◽  
Robotic Applications

Abstract This paper introduces a new generation of robotic mechanisms. Such mechanisms are intermediate between the familiar serial and the fully-parallel robotic mechanisms. They usually comprise several subassemblies that are serially connected to one another. Each subassembly is basically an over constrained fully parallel kinematic chain. Such mechanisms are called “Partially-Parallel Robotic Mechanisms.” A type synthesis of planar and spatial partially-parallel robotic mechanisms is performed. Several practical designs are then introduced and studied for future robotic applications. Several performance criteria of this type of mechanisms are discussed and compared with those of serial as well as fully-parallel robotic mechanisms. Partially-parallel mechanisms are superior than serial mechanisms in rigidity, strength precision positioning and load carrying capacity. Furthermore, they are relatively less complex and have larger range of motion than fully-parallel mechanisms.

Polymer Composite with Sisal Fiber Used for Node Reinforce in Space-Truss with Stamped Connection

2015 ◽  
Vol 719-720 ◽  
pp. 202-205
Author(s):  
Cleirton A.S. Freitas ◽  
Mucio M.S. Nobrega ◽  
Édipo A. Bezerra ◽  
Otávio R.O. Cavalcante
Keyword(s):  
Polymer Composite ◽  
Carrying Capacity ◽  
Three Dimensional ◽  
Sisal Fiber ◽  
Load Carrying Capacity ◽  
Space Truss ◽  
Load Carrying ◽  
Steel Bars ◽  
Space Trusses

Space trusses are three-dimensional structures made of steel bars very frequently used at the roof construction. The bars, with tubular section, are linking in the 3D form by connections. There are several types of connections to attach these members. The most economical connection is the staking end-flattened connection, also called typical node. The reduced cost and the fast assemblage of the truss are among their advantages. However, such connections present disadvantages like eccentricities and stiffness weakening of the tubular members. This research presents suggestions of reinforcement and constructive correction in the connection in order to increase its capacity. The base for this is the reduction of the eccentricity in typical node applying the spacer. This spacer was made by polymer composite with sisal fiber. In this work was developed experimental lab tests in prototypes with fifty four meters square of area. The results show an increase of 26% for collapse in the truss load carrying capacity when the suggested changes proposed in this article are used for the staking end-flattened connections.

scholarly journals Load carrying capacity of partially encased columns for different fire ratings

Fire Research ◽  
2016 ◽  
Author(s):  
Abdelkadir Fellouh ◽  
Nourredine Benlakehal ◽  
Paulo Piloto ◽  
Ana Ramos ◽  
Luís Mesquita
Keyword(s):  
Fire Resistance ◽  
Carrying Capacity ◽  
Three Dimensional ◽  
Thermal Inertia ◽  
Load Carrying Capacity ◽  
The Finite Element Method ◽  
Three Dimensional Model ◽  
Load Carrying ◽  
Solution Methods ◽  
Two Parameters

Partially encased columns have significant fire resistance in comparison with steel bare columns. However, it is not possible to assess the fire resistance of such members simply by considering the temperature of the steel. The presence of concrete increases the mass and thermal inertia of the member and the variation of temperature within the cross section, in both the steel and concrete components. The annex G of EN1994-1-2:20051 allows to calculate the load carrying capacity of partially encased columns, for a specific fire rating time, considering the balanced summation model. New formulas will be proposed to calculate the plastic resistance to axial compression and the effective flexural stiffness. These two parameters are used to determine the buckling resistance. The finite element method is used to compare the results for the elastic critical load and the load carrying capacity of partially encased columns for different fire ratings of 30 and 60 min. This work compares the results from both solution methods, provides the validation of the three-dimensional model and demonstrates that a new design curve should be used for the buckling analysis of partially encased columns.

Investigation of Burst Pressure in Pipes With Square Wall Thinning by Using FEA and API579 FFS-1

2013 ◽  
Author(s):  
Atsushi Yamaguchi
Keyword(s):  
Carrying Capacity ◽  
Safety Margin ◽  
Pressure Vessels ◽  
Fe Analysis ◽  
Burst Pressure ◽  
Load Carrying Capacity ◽  
Working Pressure ◽  
Accelerated Corrosion ◽  
Wall Thinning ◽  
Load Carrying

Boilers and pressure vessels are heavily used in chemical industrial plants and equipment is inspected periodically for damage. The most common type of damage is wall thinning due to Flow-Accelerated Corrosion (FAC) or corrosion under insulation (CUI). Any damage must be repaired or replaced as necessary. On the other hand, optimization of the time required in order to replace damaged equipment by evaluating the load carrying capacity of pipes with wall thinning is expected in chemical industrial field. In the present study, FE analysis is used in order to evaluate the load carrying capacity in pipes with wall thinning. Burst pressure is a measure of the load carrying capacity in pipes with wall thinning. The pipes subjected to burst testing are carbon steel tubes for pressure service STPG370 (JIS G3454). The examined wall thinning is rectangular, and the eroded depth is half the pipe wall thickness. The burst pressure is investigated by comparing the results of burst testing with the results of FE analysis. Moreover, the reduced maximum allowable working pressure (MAWPr), which is calculated by fitness-for-service (FFS) assessment, and the safety margin for burst pressure are investigated. The burst pressure calculated by FEA agrees well with the test results, except for square wall thinning for circumferential angles of less than 15°. Also, the safety margin of MAWPr based on FFS-1 Part 4 is over 4.0 times for burst pressure.

scholarly journals MECHANICAL PROPERTIES OF AN ALFISSOL SUBMITTED TO AGRICULTURAL MACHINERY TRAFFIC IN A SEMIARID REGION IN BRAZIL - DOI: 10.13083/1414-3984.v22n06a05

2014 ◽  
Vol 22 (6) ◽  
pp. 543-551
Author(s):  
Renildo Luiz Mion ◽  
Virginia Pires Pereira ◽  
Webert Alan Sombra ◽  
Karla Lúcia Batista Araújo ◽  
Silvia Ferreira da Silva
Keyword(s):  
Water Content ◽  
Carrying Capacity ◽  
Soil Samples ◽  
Semiarid Region ◽  
Load Carrying Capacity ◽  
Ground Contact ◽  
Inflation Pressure ◽  
Load Bearing Capacity ◽  
Load Carrying ◽  
Before And After

The load carrying capacity of the soil can be determined from preconsolidation curves, being sensitive to the variation of loads and extremely sensitive to changes in soil moisture. For this study, the water content in soil was 2.50% and 10.58% for the layer from 0 to 0.15 m. Soil samples were collected before and after traffic with one and two passes of a tractor weighing 7100 kg, equipped with 14.4-24 R1 bias tires on the front with inflation pressure of 82.74 kPa and 18.9-34 R1 rear tires with inflation pressure of 96.53 kPa, and a tire ground contact area of 0.11 m2 and 0.13 respectively for the front and rear tires. The speed at the time of the pass for each treatment was 2.22 m s-1. Regardless of the soil water content, the load carrying capacity increases with the traffic of machines due to reduction of voids. Preconsolidation curves should be used with caution due to the use of samples for determining the points in saturated conditions, and when recommended for load-bearing capacity, unsaturated samples should be used.

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