Effects of Moving Dynamic Tyre Loads on Tyre-Pavement Contact Stresses

2021 ◽  
pp. 253-262
Author(s):  
W.J.vdM. Steyn ◽  
A.T. Visser
Keyword(s):  
Contact Stresses

ON THE INTERACTION OF A VISCOELASTIC CYLINDRICAL PIPE WITH INNER UNIFORM COATING AND INSERTS WITH A COMPLEX PROFILE

2020 ◽  
Author(s):  
Kirill Kazakov
Keyword(s):  
Complex Shape ◽  
High Accuracy ◽  
Contact Stresses ◽  
Basis Functions ◽  
Complex Profile ◽  
Cylindrical Pipe ◽  
Interference Fit ◽  
Uniform Coating ◽  
Special Basis ◽  
Insert Region

This work is devoted to the formulation and construction of an analytical solution to the problem of contact between a cylindrical viscoelastic aging pipe with an internal thin coating and an insert having a complex shape placed inside the pipe with an interference fit. In practice, the presence of such coatings is required, for example, to protect the main structure from aggressive external or internal environments, for its electrical insulation, etc. The manufacturing process of the inner coating determines its possible heterogeneity (dependence of properties on coordinates). An insert placed inside a pipe can have a complex profile that has a rapidly changing function. Taking these features into account is important when analyzing the stress-strain state of pipes with an internal coating. Using an approach based on the use of special basis functions and the type of solution, a representation for the contact stresses in the pipe in the region of the rigid insert is obtained. This approach makes it possible to distinguish functions that describe the properties of the inner coating and the shape of the outer profile of the insert in the form of separate terms and factors in the expression for the contact stresses in the insert region. Therefore, in order to achieve high accuracy when carrying out calculations, it is sufficient to restrict ourselves to a relatively small number of terms

scholarly journals Design and manufacture of the novel drum worm pair

2020 ◽  
Vol 103 (4) ◽  
pp. 003685042098122
Author(s):  
Jingzi Zhang ◽  
Jin’ge Wang ◽  
Kai Wang
Keyword(s):  
Contact Stresses ◽  
Primary Objective ◽  
Structure Design ◽  
Worm Gear ◽  
The Novel ◽  
Bending Stress ◽  
Manufacturing Method ◽  
Design And Manufacture ◽  
Maximum Contact ◽  
Worm Drive

Although a significant amount of research on robot joint reducer was conducted, there are few systematic investigations on a novel joint reducer adopting inner worm-gear plane enveloping drum worm drive. To satisfy the development of modular robot joint, the primary objective of this paper was to systematically investigate the drum worm drive adopted in the novel joint reducer with integrated structure of drive, transmission, and support in the following aspects: meshing theory, design, analysis, and manufacture. According to the gear meshing theory, mechanical design method, classical mechanics, finite element method, and machining principle of virtual center distance, the systematic investigations around the drum worm pair applied in the novel joint reducer were conducted including the macro and micro meshing theory, structure design, mechanical and contact properties analyses, and manufacturing method. The novel joint reducer’s integrated structure was designed, and the drum worm pair’s mechanical and contact properties analyses were conducted, which showed: (1) the worm’s bending stress and deflection, worm-gear teeth’s shear stress and bending stress as well as the maximum contact stresses were all below their corresponding allowable values; (2) the maximum contact stresses appeared at the engage-in position of the worm pair opposing to the engaging-out position where the largest contact areas appeared. Then the manufacturing of drum worm’s spiral tooth was conducted via the modified 4-axis linkage CNC grinder according to the conjugate motion. Finally the novel joint reducer’s industrial prototype was assembled. The novel joint reducer with integrated structure of drive, transmission and support was designed and manufactured for the first time. The flowchart of design and manufacture of the reducer’s drum worm pair in this process was formulated, which provides a new insight on the research of joint reducers as well as other fields.

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.

scholarly journals Does laser surface texturing really have a negative impact on the fatigue lifetime of mechanical components?

Friction ◽  
2021 ◽  
Author(s):  
Chia-Jui Hsu ◽  
Andreas Stratmann ◽  
Simon Medina ◽  
Georg Jacobs ◽  
Frank Mücklich ◽  
...  
Keyword(s):  
Boundary Lubrication ◽  
Surface Texturing ◽  
Contact Stresses ◽  
Laser Surface ◽  
Laser Surface Texturing ◽  
Wear Loss ◽  
Textured Surface ◽  
Periodic Patterns ◽  
Rolling Bearings ◽  
Fatigue Lifetime

AbstractLaser surface texturing (LST) has been proven to improve the tribological performance of machine elements. The micro-scale patterns manufactured by LST may act as lubricant reservoirs, thus supplying oil when encountering insufficient lubrication. However, not many studies have investigated the use of LST in the boundary lubrication regime, likely due to concerns of higher contact stresses that can occur with the increasing surface roughness. This study aims to examine the influence of LST on the fatigue lifetime of thrust rolling bearings under boundary lubrication. A series of periodic patterns were produced on the thrust rolling bearings, using two geometrically different designs, namely cross and dimple patterns. Base oil ISO VG 100 mixed with 0.05 wt% P of zinc dialkyldithiophosphate (ZDDP) was supplied. The bearings with cross patterns reduce the wear loss by two orders of magnitude. The patterns not only retain lubricant in the textured pockets but also enhance the formation of an anti-wear tribofilm. The tribofilm generation may be improved by the higher contact stresses that occur when using the textured surface. Therefore, in contrast to the negative concerns, the ball bearings with cross patterns were instead found to increase the fatigue life by a factor of three.

Magnetic Erasures Due to Impact Induced Interfacial Heating and Magnetostriction

1999 ◽  
Vol 122 (1) ◽  
pp. 264-268 ◽  
Author(s):  
M. Suk ◽  
P. Dennig ◽  
D. Gillis
Keyword(s):  
Thermal Conductivity ◽  
High Speed ◽  
Magnetic Layer ◽  
Substrate Material ◽  
Contact Stresses ◽  
Dominant Factor ◽  
Disk Drives ◽  
Mechanical Contact ◽  
Low Thermal Conductivity ◽  
Interfacial Temperature

High-velocity intermittent contacts between a slider and a disk may lead to data erasure due to interfacial heating and high-speed mechanical contact stresses. These potential modes of erasure are investigated by artificially introducing high contact stresses that are not likely to be observed in disk drives. Nevertheless, the mechanisms of erasure are delineated in this study with little ambiguity by comparing the results from three different substrate materials, namely Al-Mg, glass, and Si. We show that written flux patterns can be erased if either the substrate material has low thermal conductivity or if the magnetic layer is damaged. We conclude that if the disk is not plastically damaged by high-speed contacts, then the magnetostriction effect or stress-induced erasure is insignificant. In this case, the dominant factor in erasure is a rise in the interfacial temperature, which is exacerbated by low thermal conductivity of the substrate. [S0742-4787(00)03401-9]

Biomechanical Comparison of Kinematic and Mechanical Knee Alignment Techniques in a Computer Simulation Medial Pivot Total Knee Arthroplasty Model

2021 ◽  
Author(s):  
Young Dong Song ◽  
Shinichiro Nakamura ◽  
Shinichi Kuriyama ◽  
Kohei Nishitani ◽  
Hiromu Ito ◽  
...  
Keyword(s):  
Femoral Component ◽  
Knee Flexion ◽  
External Rotation ◽  
Knee Kinematics ◽  
Lateral Compartment ◽  
Contact Stresses ◽  
Contact Forces ◽  
Medial Compartment ◽  
Tibial Insert ◽  
Medial Pivot

AbstractSeveral concepts may be used to restore normal knee kinematics after total knee arthroplasty. One is a kinematically aligned (KA) technique, which restores the native joint line and limb alignment, and the other is the use of a medial pivot knee (MPK) design, with a ball and socket joint in the medial compartment. This study aimed to compare motions, contact forces, and contact stress between mechanically aligned (MA) and KA (medial tilt 3° [KA3] and 5° [KA5]) models in MPK. An MPK design was virtually implanted with MA, KA3, and KA5 in a validated musculoskeletal computer model of a healthy knee, and the simulation of motion and contact forces was implemented. Anteroposterior (AP) positions, mediolateral positions, external rotation angles of the femoral component relative to the tibial insert, and tibiofemoral contact forces were evaluated at different knee flexion angles. Contact stresses on the tibial insert were calculated using finite element analysis. The AP position at the medial compartment was consistent for all models. From 0° to 120°, the femoral component in KA models showed larger posterior movement at the lateral compartment (0.3, 6.8, and 17.7 mm in MA, KA3, and KA5 models, respectively) and larger external rotation (4.2°, 12.0°, and 16.8° in the MA, KA3, and KA5 models, respectively) relative to the tibial component. Concerning the mediolateral position of the femoral component, the KA5 model was positioned more medially. The contact forces at the lateral compartment of all models were larger than those at the medial compartment at >60° of knee flexion. The peak contact stresses on the tibiofemoral joint at 90° and 120° of knee flexion were higher in the KA models. However, the peak contact stresses of the KA models at every flexion angle were <20 MPa. The KA technique in MPK can successfully achieve near-normal knee kinematics; however, there may be a concern for higher contact stresses on the tibial insert.

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