scholarly journals Numerical Investigation into the Effect of Geometric Gap Idealisation on Wheel-Rail Rolling Contact in Presence of Yaw Angle

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Boyang An ◽  
Jing Wen ◽  
Panjie Wang ◽  
Ping Wang ◽  
Rong Chen ◽  
...  
Keyword(s):  
Numerical Investigation ◽  
Contact Mechanics ◽  
Contact Force ◽  
Rolling Contact ◽  
Fast Calculation ◽  
Contact Patch ◽  
Track Dynamics ◽  
Yaw Angle ◽  
Contact Modelling

For a fast calculation of vehicle-track dynamics and wheel-rail contact mechanics, wheel-rail contact geometric gap is usually idealised in elliptic or nonelliptic form. These two idealisations deviate from the actual one if the lateral combined curvature within the contact patch is not constant or the yaw angle of wheelset exists. The influence of these idealisations on contact solution has not yet been deeply understood, and thus the accuracy of simplified contact modelling applied to vehicle-track dynamics and wheel-rail contact mechanics remains uncertain. This paper presents a numerical methodology to treat 3D wheel-rail rolling contact, in which the asymmetric geometric gap due to yaw angle is fully taken into account. The attention of this work is placed on investigating the effect of geometric gap idealisation on wheel-rail contact force, rolling contact solution, and wear distribution. It can help with the effective wheel-rail contact modelling on the computation of both vehicle-track dynamics and wheel-rail contact mechanics.

Lateral Extra-articular Tenodesis Alters Lateral Compartment Contact Mechanics under Simulated Pivoting Maneuvers: An In Vitro Study

2021 ◽  
pp. 036354652110282
Author(s):  
Niv Marom ◽  
Hamidreza Jahandar ◽  
Thomas J. Fraychineaud ◽  
Zaid A. Zayyad ◽  
Hervé Ouanezar ◽  
...  
Keyword(s):  
Contact Mechanics ◽  
Contact Force ◽  
Contact Stress ◽  
Tibial Plateau ◽  
Cruciate Ligament ◽  
In Vitro Study ◽  
Lateral Compartment ◽  
Lateral Tibial Plateau ◽  
Intact Knee

Background: There is concern that utilization of lateral extra-articular tenodesis (LET) in conjunction with anterior cruciate ligament (ACL) reconstruction (ACLR) may disturb lateral compartment contact mechanics and contribute to joint degeneration. Hypothesis: ACLR augmented with LET will alter lateral compartment contact mechanics in response to simulated pivoting maneuvers. Study Design: Controlled laboratory study. Methods: Loads simulating a pivot shift were applied to 7 cadaveric knees (4 male; mean age, 39 ± 12 years; range, 28-54 years) using a robotic manipulator. Each knee was tested with the ACL intact, sectioned, reconstructed (via patellar tendon autograft), and, finally, after augmenting ACLR with LET (using a modified Lemaire technique) in the presence of a sectioned anterolateral ligament and Kaplan fibers. Lateral compartment contact mechanics were measured using a contact stress transducer. Outcome measures were anteroposterior location of the center of contact stress (CCS), contact force from anterior to posterior, and peak and mean contact stress. Results: On average, augmenting ACLR with LET shifted the lateral compartment CCS anteriorly compared with the intact knee and compared with ACLR in isolation by a maximum of 5.4 ± 2.3 mm ( P < .001) and 6.0 ± 2.6 mm ( P < .001), respectively. ACLR augmented with LET also increased contact force anteriorly on the lateral tibial plateau compared with the intact knee and compared with isolated ACLR by a maximum of 12 ± 6 N ( P = .001) and 17 ± 10 N ( P = .002), respectively. Compared with ACLR in isolation, ACLR augmented with LET increased peak and mean lateral compartment contact stress by 0.7 ± 0.5 MPa ( P = .005) and by 0.17 ± 0.12 ( P = .006), respectively, at 15° of flexion. Conclusion: Under simulated pivoting loads, adding LET to ACLR anteriorized the CCS on the lateral tibial plateau, thereby increasing contact force anteriorly. Compared with ACLR in isolation, ACLR augmented with LET increased peak and mean lateral compartment contact stress at 15° of flexion. Clinical Relevance: The clinical and biological effect of increased anterior loading of the lateral compartment after LET merits further investigation. The ability of LET to anteriorize contact stress on the lateral compartment may be useful in knees with passive anterior subluxation of the lateral tibia.

scholarly journals On the influence of conformity on wheel–rail rolling contact mechanics

2016 ◽  
Vol 103 ◽  
pp. 647-667 ◽  
Author(s):  
Julio Blanco-Lorenzo ◽  
Javier Santamaria ◽  
Ernesto G. Vadillo ◽  
Nekane Correa
Keyword(s):  
Contact Mechanics ◽  
Rolling Contact

scholarly journals Applying Two Simplified Ellipse-Based Tangential Models to Wheel-Rail Contact Using Three Alternative Nonelliptic Adaptation Approaches: A Comparative Study

2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Boyang An ◽  
Ping Wang ◽  
Jiayi Zhou ◽  
Rong Chen ◽  
Jingmang Xu ◽  
...  
Keyword(s):  
Comparative Study ◽  
Computational Cost ◽  
Rolling Contact ◽  
Railway Vehicle ◽  
Normal Contact ◽  
Tangential Contact ◽  
Track Dynamics ◽  
Contact Models ◽  
Creep Force

In the modeling of railway vehicle-track dynamics and wheel-rail damage, simplified tangential contact models based on ellipse assumption are usually used due to strict limitation of computational cost. Since most wheel-rail contact cases appear to be nonelliptic shapes, a fast and accurate tangential model for nonelliptic contact case is in demand. In this paper, two ellipse-based simplified tangential models (i.e., FASTSIM and FaStrip) using three alternative nonelliptic adaptation approaches, together with Kalker’s NORM algorithm, are applied to wheel-rail rolling contact cases. It aims at finding the best approach for dealing with nonelliptic rolling contact. Compared to previous studies, the nonelliptic normal contact solution in the present work is accurately solved rather than simplification. Therefore, it can avoid tangential modeling evaluation affected by inaccurate normal contact solution. By comparing with Kalker’s CONTACT code, it shows both FASTSIM-based and FaStrip-based models can provide accurate global creep force. With regard to local rolling contact solution, only the accuracy of FaStrip-based models is satisfactory. Moreover, Ayasse-Chollet’s local ellipse approach appears to be the best choice for nonelliptic adaptation.

Stability Analysis of Planar Grasp with 2D-Virtual Spring Model

1999 ◽  
Vol 11 (4) ◽  
pp. 274-282 ◽  
Author(s):  
Takayoshi Yamada ◽  
◽  
Sushanta Kumar Saha ◽  
Nobuharu Mimura ◽  
Yasuyuki Funahashi ◽  
...  
Keyword(s):  
Contact Force ◽  
External Disturbance ◽  
Rolling Contact ◽  
Initial Contact ◽  
Spring Model ◽  
Spring Stiffness ◽  
Grasp Stability ◽  
Stiffness Matrices ◽  
The Relationship ◽  
Special Case

We analyze stability of planar grasp using a 2D virtual spring model. A 2D virtual spring model is widely used to explore frictionless grasp, but the direction of contact force has not been studied for a grasped object displaced by external disturbance. Finger displacement is restricted to the normal at initial contact. We introduce a 2D spring model for a frictionless case. The direction of contact force is explicitly formulated. Using potential energy, we analyze stability of frictionless grasp and show that the 1D-spring model is a special case of our proposed 2D-spring model. Frictional grasp stability is also studied using rolling contact. Numerical examples of 2-fingered grasp demonstrate the effects of parameters such as spring stiffness and contact force. It is shown that an optimum force exists for stabilizing frictionless grasp. It is proved that friction enhances grasp stability from the relationship between frictionless and frictional stiffness matrices. Stiffness conditions for stabilizing 3-fingered grasp is clarified.

scholarly journals A Tribometric Device for the Rolling Contact of Soft Elastomers

2021 ◽  
Author(s):  
Brodie Hoyer ◽  
Rong Long ◽  
Mark E. Rentschler
Keyword(s):  
Contact Mechanics ◽  
Fundamental Problem ◽  
Finite Thickness ◽  
Medical Robotics ◽  
Adhesive Contact ◽  
Rolling Contact ◽  
Experimental Investigations ◽  
Pdms Substrate ◽  
Textured Surfaces ◽  
Tribometric Device

Abstract Rolling contact experimentation is a viable and instructive method for exploring the adhesive contact between surfaces. When applied to soft elastomeric or engineered surfaces, the results of such experiments can provide insights relevant to medical robotics, soft gripping applications, and reversible dry adhesives for bandages or wearable devices. We have designed and built a tribometric device to capture normal and tangential forces between a rolling indenter and substrate correlated with contact area imaging. The device was validated using an experimental setup involving a rigid, nominally smooth acrylic cylinder rolling against a flat polydimethylsiloxame (PDMS) substrate, the results of which matched favorably with accepted contact mechanics theories. The second test involved an indenter with a rigid core and thin (3 mm) smooth shell of a highly deformable, viscoelastic polyvinyl chloride (PVC) rolling on the same PDMS substrate. This test deviated significantly from analytical predictions, highlighting the effects of finite-thickness effects, viscoelasticity, and interfacial slip. This device will facilitate experimental investigations of the rolling contact mechanics between textured surfaces and soft tissue-like materials, which is an important fundamental problem in medical robotics.

Numerical investigation on the rolling contact wear and fatigue of laser dispersed quenched U71Mn rail

2021 ◽  
Vol 143 ◽  
pp. 106010
Author(s):  
Jizhong Zhao ◽  
Hongchen Miao ◽  
Qianhua Kan ◽  
Peilin Fu ◽  
Li Ding ◽  
...  
Keyword(s):  
Numerical Investigation ◽  
Rolling Contact ◽  
Contact Wear

The Investigation of Energy Loss in Conformal Contact Mechanics of Carpal-Radial Components in Wrist Arthroplasty

2014 ◽  
Author(s):  
Mohammad Hodaei ◽  
Kambiz Farhang
Keyword(s):  
Surface Roughness ◽  
Energy Loss ◽  
Contact Mechanics ◽  
Contact Force ◽  
Rough Surfaces ◽  
Approximate Equation ◽  
Integral Function ◽  
Contact Model ◽  
Metal Debris ◽  
Surface Separation

The contact mechanics of Wrist prosthetic implant is considered in which the surface roughness of the implant is included. Total wrist replacements are developed to perform wrist function as near normal as possible. The main goal of wrist replacement surgery is to relieve patients from painful arthritis and to maintain function in the wrist and hand. The gradual wearing away of the cartilage covering on bones can lead to the most common form of arthritis, usually osteoarthritis. Wear is a very important issue in wrist implant. Metal debris caused by excessive wear in wrist implant can lead to toxicity and patient discomfort. Since implant wear can be the result of contact between surfaces of Carpal and Radial components, so the investigation of the effect of roughness between wrist components and establishing a model for interaction of surface roughness is very important. There are several different designs of wrist implant. Most of them have two components that are made of metal. A high quality plastic called polyethylene is used as a space between the two components. The purpose of this paper is to investigate the effect of roughness between interaction of these metal and polyethylene in wrist implants. This paper develops a contact model to treat the interaction of Carpal - Radial Components. The contact model describes the interaction of implant rough surfaces including both elastic and plastic deformations. In the model, surfaces are investigated as macroscopically conforming semi-Cylinder containing micron-scale roughness. The derived equations relate contact force on the implant and the minimum mean surface separation of the rough surfaces. Based on the distribution of asperity heights, the force is expressed using statistical integral function of asperity heights over the possible region of interaction of the roughness of the implant surfaces. Closed-form approximate equation relating contact force and minimum separation is used to obtain energy loss per cycle in a load-unload sequence applied to the implant.

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