scholarly journals 3-D Thermomechanical Tire–Pavement Interaction Model for Evaluation of Pavement Skid Resistance

2020 ◽  
pp. 036119812096310
Author(s):  
K. Anupam ◽  
T. Tang ◽  
C. Kasbergen ◽  
A. Scarpas ◽  
S. Erkens
Keyword(s):  
Ambient Temperature ◽  
Three Dimensional ◽  
Interaction Model ◽  
Surface Characteristics ◽  
Heat Transfer Analysis ◽  
Skid Resistance ◽  
Proposed Model ◽  
Parametric Studies ◽  
Pavement Temperature ◽  
Effects Of Temperature

Skid resistance is known to be affected by environmental conditions such as ambient temperature and pavement temperature. Finite element (FE) modeling has been an effective and efficient way to study the effects of temperature on skid resistance. However, existing FE models either are not able to incorporate the pavement surface characteristics or only perform heat transfer analysis per the two-dimensional (2-D) cross-section of the tire, which could lead to inaccurate predictions of skid resistance. Therefore, the aim of the current study was to develop a three-dimensional, coupled thermomechanical tire–pavement interaction model to investigate the variations in skid resistance as a function of ambient temperature and pavement temperature. The advantages and capability of the proposed model were highlighted by comparing the tire temperature profiles predicted by the proposed model and by the existing 2-D staggered model. Parametric studies of various factors that affect skid resistance were carried out. On the basis of the output results, a relationship between skid resistance and different parameters is proposed.

A Three-Dimensional Pedestrian–Structure Interaction Model for General Applications

2018 ◽  
Vol 18 (09) ◽  
pp. 1850107 ◽  
Author(s):  
Yan-An Gao ◽  
Qing-Shan Yang ◽  
Yun Dong
Keyword(s):  
Large Scale ◽  
Damping Ratio ◽  
Three Dimensional ◽  
Interaction Model ◽  
Dynamic Interaction ◽  
Structure Interaction ◽  
Numerical Studies ◽  
Structure Dynamic ◽  
Proposed Model ◽  
Reaction Forces

A three-dimensional (3D) pedestrian–structure interaction (PSI) system based on the biomechanical bipedal model is presented for general applications. The pedestrian is modeled by a bipedal mobile system with one lump mass and two compliant legs, which comprise damping and spring elements. The continuous gaits of the pedestrian are maintained by a self-driven walking kinetic energy, which is a new driven mechanism for the mobile unit. This self-driven mechanism enables the pedestrian to operate at a varying total energy level, as an important component for further modeling of the crowd-structure dynamic interaction. Numerical studies show that the pedestrian walking on the structure leads to a reduction in the natural frequency, but an increase in the damping ratio of the structure. This model can also reproduce the reaction forces between the feet and structure, similar to those measured in the field. In addition, the proposed model can well describe the 3D pedestrian–structure dynamic interaction. It is recommended for use in further study of more complicated scenarios such as the dynamic interaction between a large scale kinetic crowd and slender footbridge.

Thermal Analysis of Irradiated Fuel Subassemblies and Fuel Pins During Storage in Concrete Pits of Head-End Facility

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
M. Rajendrakumar ◽  
K. Velusamy ◽  
P. Selvaraj ◽  
P. Chellapandi
Keyword(s):  
Radiation Heat Transfer ◽  
Three Dimensional ◽  
Concrete Structures ◽  
Heat Transfer Analysis ◽  
Fuel Pin ◽  
Parametric Studies ◽  
Test Reactor ◽  
Forced Cooling ◽  
Conjugate Conduction ◽  
Irradiated Fuel

Irradiated fuel subassembly (SA)/fuel pins, with significant decay heat are transported from reactor and stored in hot cells (HCs) before reprocessing. During transportation they are heavily shielded and no forced cooling is provided. The HCs are made of concrete structures, the outer surfaces of which are force cooled. During these processes, the fuel pin clad temperature and concrete temperatures are to be limited within specific safety limits. These temperatures are function of the decay power and geometric details of surrounding structures. To predict these temperatures, three-dimensional conjugate conduction–convection–radiation heat transfer analysis has been carried out. For this purpose, the computational fluid dynamics (CFD) code STAR-CD has been utilized, wherein individual fuel pins, steel cans, hexagonal wrapper, lead shielding blocks, and concrete structures have been considered in detail. Based on parametric studies pertaining to fuel pin transportation, it is established that for a decay power of 150 W, natural convection is adequate with maximum clad temperature of 686 K. From the studies related to storage in HCs, it is seen that nine fast breeder test reactor (FBTR) SA can stored in hot cell-1 (HC-1), with a decay power of 31.3 W per SA, to respect the temperature limits. For 3 prototype fast breeder reactor (PFBR) cans and 2 FBTR cans stored in hot cell-3 (HC-3), a decay power of 12.5 W per FBTR can and 44 W per PFBR can, can be handled without exceeding temperature limits.

Aggregate Characteristics-Based Preventive Maintenance Treatments for Optimized Skid Resistance of Pavements

2020 ◽  
Vol 2674 (12) ◽  
pp. 372-384
Author(s):  
Joshua Qiang Li ◽  
Dominique Pittenger ◽  
Kelvin Wang ◽  
Guangwei Yang ◽  
Musharraf Zaman ◽  
...  
Keyword(s):  
Preventive Maintenance ◽  
Life Cycle Cost ◽  
Imaging System ◽  
Three Dimensional ◽  
Surface Characteristics ◽  
Field Testing ◽  
Morphological Characterization ◽  
Skid Resistance ◽  
Pavement Surface ◽  
Main Component

Skid resistance of pavements plays a significant role in roadway safety. Preventive maintenance (PM) treatments have been used to restore pavement condition and retard future deterioration. As aggregate is the main component of such treatments, this study assessed the skid resistance of pavements in Oklahoma following PM treatment application to evaluate whether skid resistance is maintained or improved and economics are optimized, and presents a methodology to assist pavement engineers manage skid resistance. The 13 commonly used sources of aggregates in Oklahoma were acquired for aggregate morphological characterization in the laboratory in relation to shape, angularity, and surface texture-related index properties, using the Aggregate Imaging System before and after Micro-Deval abrasion. Accordingly, a systematic experimental design was developed to include 45 field testing sites constructed with typical Oklahoma PM treatments and the common aggregate sources. Multiple rounds of field data collection were performed during a 3-year period using the most recent three-dimensional (3D) laser imaging technology for pavement surface characteristics and a Grip Tester for skid resistance. The impacts of aggregate properties and pavement surface characteristics on the skid resistance were investigated and used to develop statistical deterioration models. Subsequently, life cycle cost analysis and performance-based sensitivity analysis were conducted using the developed deterioration model. This study presents a detailed analysis of aggregate characteristics and its relationship to skid resistance of pavements. An understanding of these relationships and application of the presented methodology can result in improvements in pavement safety with enhanced stewardship of financial resources.

Voids in Quenched Nickel

1968 ◽  
Vol 26 ◽  
pp. 266-267
Author(s):  
J. J. Laidler
Keyword(s):  
Electron Beam ◽  
Ambient Temperature ◽  
Cooling Rate ◽  
Three Dimensional ◽  
Cooling Curve ◽  
Polycrystalline Nickel ◽  
Quenching Temperature ◽  
Long Tail ◽  
Diffusion Pump

The presence of three-dimensional voids in quenched metals has long been suspected, and voids have indeed been observed directly in a number of metals. These include aluminum, platinum, and copper, silver and gold. Attempts at the production of observable quenched-in defects in nickel have been generally unsuccessful, so the present work was initiated in order to establish the conditions under which such defects may be formed.Electron beam zone-melted polycrystalline nickel foils, 99.997% pure, were quenched from 1420°C in an evacuated chamber into a bath containing a silicone diffusion pump fluid . The pressure in the chamber at the quenching temperature was less than 10-5 Torr . With an oil quench such as this, the cooling rate is approximately 5,000°C/second above 400°C; below 400°C, the cooling curve has a long tail. Therefore, the quenched specimens are aged in place for several seconds at a temperature which continuously approaches the ambient temperature of the system.

Thermomechanical Coupling of a Hyper-viscoelastic Truck Tire and a Pavement Layer and its Impact on Three-dimensional Contact Stresses

2021 ◽  
pp. 036119812110171
Author(s):  
Angeli Jayme ◽  
Imad L. Al-Qadi
Keyword(s):  
Contact Stress ◽  
Contact Area ◽  
Three Dimensional ◽  
Interaction Model ◽  
Rolling Resistance ◽  
Contact Stresses ◽  
Thermomechanical Coupling ◽  
Temperature Profiles ◽  
Near Surface ◽  
Truck Tire

A thermomechanical coupling between a hyper-viscoelastic tire and a representative pavement layer was conducted to assess the effect of various temperature profiles on the mechanical behavior of a rolling truck tire. The two deformable bodies, namely the tire and pavement layer, were subjected to steady-state-uniform and non-uniform temperature profiles to identify the significance of considering temperature as a variable in contact-stress prediction. A myriad of ambient, internal air, and pavement-surface conditions were simulated, along with combinations of applied tire load, tire-inflation pressure, and traveling speed. Analogous to winter, the low temperature profiles induced a smaller tire-pavement contact area that resulted in stress localization. On the other hand, under high temperature conditions during the summer, higher tire deformation resulted in lower contact-stress magnitudes owing to an increase in the tire-pavement contact area. In both conditions, vertical and longitudinal contact stresses are impacted, while transverse contact stresses are relatively less affected. This behavior, however, may change under a non-free-rolling condition, such as braking, accelerating, and cornering. By incorporating temperature into the tire-pavement interaction model, changes in the magnitude and distribution of the three-dimensional contact stresses were manifested. This would have a direct implication on the rolling resistance and near-surface behavior of flexible pavements.

Three-dimensional heat transfer analysis of flat-plate oscillating heat pipes

2021 ◽  
pp. 117189
Author(s):  
Kimihide Odagiri ◽  
Kieran Wolk ◽  
Stefano Cappucci ◽  
Stefano Morellina ◽  
Scott Roberts ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Three Dimensional ◽  
Heat Pipes ◽  
Heat Transfer Analysis

Effects of temperature and concomitant change in pH on muscle

1990 ◽  
Vol 259 (2) ◽  
pp. R204-R209 ◽  
Author(s):  
E. D. Stevens ◽  
R. E. Godt
Keyword(s):  
Ambient Temperature ◽  
Calcium Sensitivity ◽  
Skinned Fibers ◽  
Concomitant Increase ◽  
Concomitant Change ◽  
Effects Of Temperature ◽  
Contractile Performance

Contractile performance decreases with a decrease in temperature and increases with an increase in pH. In general, a decrease in ambient temperature is associated with an increase of the pH of the intracellular and extracellular fluids of ectotherms. Thus the concomitant increase in pH will to some extent counteract the effect of the decrease in temperature. We review the magnitude of this effect and show that it is modest for force (24%) but is small or negligible for speed or for variables involving time. Experiments with skinned fibers yield similar results to those with intact fibers. We argue that one important effect of the concomitant increase in pH is that it causes an increase in calcium sensitivity and that there may be a considerable metabolic saving associated with releasing less calcium at lower temperatures.

scholarly journals Titanium oral implants: surface characteristics, interface biology and clinical outcome

2010 ◽  
Vol 7 (suppl_5) ◽  
Author(s):  
Anders Palmquist ◽  
Omar M. Omar ◽  
Marco Esposito ◽  
Jukka Lausmaa ◽  
Peter Thomsen
Keyword(s):  
Surface Properties ◽  
Cellular Response ◽  
Randomized Clinical Trials ◽  
Three Dimensional ◽  
Cell Communication ◽  
Surface Characteristics ◽  
Titanium Implants ◽  
Material Surface ◽  
Oral Implants

Bone-anchored titanium implants have revolutionized oral healthcare. Surface properties of oral titanium implants play decisive roles for molecular interactions, cellular response and bone regeneration. Nevertheless, the role of specific surface properties, such as chemical and phase composition and nanoscale features, for the biological in vivo performance remains to be established. Partly, this is due to limited transfer of state-of-the-art preparation techniques to complex three-dimensional geometries, analytical tools and access to minute, intact interfacial layers. As judged by the available results of a few randomized clinical trials, there is no evidence that any particular type of oral implant has superior long-term success. Important insights into the recruitment of mesenchymal stem cells, cell–cell communication at the interface and high-resolution imaging of the interface between the surface oxide and the biological host are prerequisites for the understanding of the mechanisms of osseointegration. Strategies for development of the next generation of material surface modifications for compromised tissue are likely to include time and functionally programmed properties, pharmacological modulation and incorporation of cellular components.

Study on the generalized k-Hilfer–Prabhakar fractional viscoelastic–plastic model

2021 ◽  
pp. 108128652110258
Author(s):  
Yi-Ying Feng ◽  
Xiao-Jun Yang ◽  
Jian-Gen Liu ◽  
Zhan-Qing Chen
Keyword(s):  
Constitutive Model ◽  
Three Dimensional ◽  
Sensitivity Analyses ◽  
Creep Process ◽  
Fractional Operator ◽  
Modified Model ◽  
Proposed Model ◽  
Accelerated Creep ◽  
The Laplace Transform ◽  
Classical Models

The general fractional operator shows its great predominance in the construction of constitutive model owing to its agility in choosing the embedded parameters. A generalized fractional viscoelastic–plastic constitutive model with the sense of the k-Hilfer–Prabhakar ( k-H-P) fractional operator, which has the character recovering the known classical models from the proposed model, is established in this article. In order to describe the damage in the creep process, a time-varying elastic element [Formula: see text] is used in the proposed model with better representation of accelerated creep stage. According to the theory of the kinematics of deformation and the Laplace transform, the creep constitutive equation and the strain of the modified model are established and obtained. The validity and rationality of the proposed model are identified by fitting with the experimental data. Finally, the influences of the fractional derivative order [Formula: see text] and parameter k on the creep process are investigated through the sensitivity analyses with two- and three-dimensional plots.

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