Experimental Results and Analysis of Aircraft Tire-Test Drum Interaction

1997 ◽  
Vol 25 (1) ◽  
pp. 43-62 ◽  
Author(s):  
N. Lindsley ◽  
J. Medzorian ◽  
J. Padovan
Keyword(s):  
Contact Pressure ◽  
Contact Area ◽  
Contact Length ◽  
Landing Gear ◽  
Maximum Pressure ◽  
Test Surface ◽  
Normal Contact ◽  
Automobile Tire ◽  
Normal Contact Pressure ◽  
Footprint Area

Abstract Although aircraft tires are traditionally tested on external drum dynamometers, the effects of the curvature of the test surface on the normal contact pressure distribution and footprint area of an aircraft tire have not previously been addressed. Using the tire force machine (TFM) at the Wright Laboratory Landing Gear Development Facility (LGDF), trends in tire footprint area and normal contact pressure distributions were investigated for concave, flat, and convex surfaces. This evaluation was performed using the F-16 radial (25.5×8.0 14PR) main landing gear tire at rated load (16,200 lbf) and inflation pressure (310 psi). The trends for overall tire footprint behavior indicate that the more convex the surface, the smaller the contact area and the larger the normal contact pressure. Conversely, the more concave the surface, the larger the contact area and the smaller the normal contact pressures. All data were made symmetric about the longitudinal and lateral centerlines. This process and its effect on the data are discussed at length in the analysis sections. Additionally, it was found that after normalizing the normal contact pressure data with respect to contact length and maximum pressure for the individual tire ribs, the normal contact pressure longitudinal distributions were “identical” (within ±5%) regardless of surface curvature. Comparisons are made with numerical experiments on a treadless, homogeneous polyurethane automobile tire.

Conditions for Sticking Friction between Aluminium Alloy AA6060 and Tool Steel in Hot Forming

2011 ◽  
Vol 491 ◽  
pp. 121-128 ◽  
Author(s):  
F. Widerøe ◽  
T. Welo
Keyword(s):  
Aluminium Alloy ◽  
Contact Pressure ◽  
Tool Steel ◽  
Contrast Material ◽  
Stick Slip ◽  
Normal Contact ◽  
Bulk Forming ◽  
Instantaneous Temperature ◽  
Normal Contact Pressure ◽  
Rotational Method

The frictional conditions between an aluminium AA6060 alloy and tool steel in hot bulk forming have been investigated. The compressive-rotational method for frictional measurements, presented herein, represents an innovative approach for defining the thermo-mechanical conditions required for sticking friction at the interface between the two metals. Aluminium disks with inserted contrast material were subjected to a variety of pressures and rotated at one end at temperatures ranging from 250 °C to 500 °C. Visual inspection of the surfaces in combination with sectioning of the deformed disks formed a method for studying how different factors affect a stick-slip criterion in metal forming. It was found that the normal contact pressure required for sticking to occur was strongly dependent on the instantaneous temperature. When comparing the normal contact pressureqwith the characteristic shear strengthkof the aluminium alloy,q/k> 0.6 yielded sticking friction for temperatures above 300 °C, while a ratio of 0.7 was required for the lower temperatures.

Repair of Lateral Meniscus Posterior Horn Detachment Lesions

2012 ◽  
Vol 40 (11) ◽  
pp. 2604-2609 ◽  
Author(s):  
Carl K. Schillhammer ◽  
Frederick W. Werner ◽  
Matthew G. Scuderi ◽  
John P. Cannizzaro
Keyword(s):  
Acl Reconstruction ◽  
Contact Pressure ◽  
Contact Area ◽  
Lateral Meniscus ◽  
Posterior Horn ◽  
Normal Contact ◽  
Intact State ◽  
Peak Contact Pressure ◽  
Maximum Contact ◽  
Contact Pressures

Background: Posterior horn detachment (PHD) lesions of the lateral meniscus are commonly associated with acute anterior cruciate ligament (ACL) tears. Multiple surgeons have advocated for repair of this lesion at the time of ACL reconstruction. However, the biomechanical consequences of this lesion and its subsequent repair have not been evaluated. Hypothesis: The PHD lesion of the lateral meniscus will lead to increased tibiofemoral contact pressures, and repair of this lesion to bone via a tibial tunnel can restore normal contact pressures during simulated gait. Study Design: Controlled laboratory study. Methods: Lateral compartment contact pressures were measured via a sensor on the tibial plateau in 8 cadaver knees with the knee intact, after sectioning the posterior horn of the lateral meniscus to simulate PHD, and after repairing the injury. The repair was performed using an ACL tunnel guide to drill a tunnel from the anteromedial tibia to the posterior horn attachment site. Dynamic pressure data were continuously collected using a conductive ink pressure sensing system while each knee was moved through a physiological gait flexion cycle. Results: Posterior horn detachment caused a significant increase in tibiofemoral peak contact pressure from 2.8 MPa to 4.2 MPa ( P = .03). After repair of the lesion to bone was performed through a transtibial tunnel, the peak contact pressure was 2.9 MPa. Posterior horn detachment also significantly decreased the maximum contact area over which tibiofemoral pressure is distributed from 451 mm2 in the intact state to 304 mm2 in the detached state. Repair of the PHD lesion increased the maximum contact area to 386 mm2, however, this area was also significantly less than in the intact state ( P = .05). Conclusion: Posterior horn detachment of the lateral meniscus causes increased peak tibiofemoral contact pressure. The peak pressure can be reduced to a normal level with repair of the lesion to bone via a transtibial tunnel. Clinical Relevance: Posterior horn detachment of the lateral meniscus is a lesion often associated with an acute ACL tear. Debate exists concerning the importance of repairing PHD lesions at the time of ACL reconstruction. The data provided in this study may influence surgeons’ management of the lesion.

Physics-Based Flexible Tire Model Integrated With LuGre Tire Friction for Transient Braking and Cornering Analysis

2016 ◽  
Vol 11 (3) ◽  
Author(s):  
Hiroki Yamashita ◽  
Paramsothy Jayakumar ◽  
Hiroyuki Sugiyama
Keyword(s):  
Finite Element ◽  
Contact Pressure ◽  
Friction Model ◽  
Distributed Parameter ◽  
Force Model ◽  
Tire Model ◽  
Normal Contact ◽  
Contact Patch ◽  
Normal Contact Pressure ◽  
Tire Friction

In transient vehicle maneuvers, structural tire deformation due to the large load transfer causes abrupt change in normal contact pressure and slip distribution over the contact patch, and it has a dominant effect on characterizing the transient braking and cornering forces including the history-dependent friction-induced hysteresis effect. To account for the dynamic coupling of structural tire deformations and the transient tire friction behavior, a physics-based flexible tire model is developed using the laminated composite shell element based on the absolute nodal coordinate formulation and the distributed parameter LuGre tire friction model. In particular, a numerical procedure to integrate the distributed parameter LuGre tire friction model into the finite-element based spatial flexible tire model is proposed. To this end, the spatially discretized form of the LuGre tire friction model is derived and integrated into the finite-element tire model such that change in the normal contact pressure and slip distributions over the contact patch predicted by the deformable tire model enters into the spatially discretized LuGre tire friction model to predict the transient shear contact stress distribution. By doing so, the structural tire deformation and the LuGre tire friction force model are dynamically coupled in the final form of the equations, and these equations are integrated simultaneously forward in time at every time step. The tire model developed is experimentally validated and several numerical examples for hard braking and cornering simulation are presented to demonstrate capabilities of the physics-based flexible tire model developed in this study.

Application of Gap Element Method to Wheel/Rail Contact Problem Based on V-5

2013 ◽  
Vol 344 ◽  
pp. 46-54
Author(s):  
Jun Jie Zhong ◽  
Bing Wu ◽  
Ze Feng Wen ◽  
Xin Zhao ◽  
Xue Song Jin
Keyword(s):  
Finite Element ◽  
Contact Pressure ◽  
Two Dimensions ◽  
Vector Form ◽  
Normal Contact ◽  
Large Rotation ◽  
Gap Element ◽  
Normal Contact Pressure ◽  
Rolling Wheel ◽  
Element Method

The vector form intrinsic finite element (V-5) method and the gap element method are combined to solve the static wheel/rail contact in two-dimensions in this paper to obtain the wheel/rail normal contact pressure, which would be compared with the normal contact pressure of ABAQUS and Hertz theory. The results showed that the contact pressure distribution of V-5 was consistent with ABAQUS and Hertzs, and the mechanical behavior of contact area was reasonable under the circumstance of different axle loads. Besides, it also verified the feasibility of adopting gap elements method to solve the static wheel/rail contact on the basis of vector form finite element method, which with the superiority of large rotation and large deformation, and laid the foundation of rolling wheel-rail contact behavior analysis.

scholarly journals Impact of Nonlinearity of The Contact Layer Between Elements Joined in a Multi-Bolted System on Its Preload

2017 ◽  
Vol 22 (4) ◽  
pp. 921-930
Author(s):  
R. Grzejda
Keyword(s):  
Physical Model ◽  
Linear Model ◽  
Contact Pressure ◽  
Contact Layer ◽  
Bolted Joints ◽  
Assembly Process ◽  
Normal Contact ◽  
Winkler Model ◽  
Normal Contact Pressure

Abstract The paper deals with modelling and calculations of asymmetrical multi-bolted joints at the assembly stage. The physical model of the joint is based on a system composed of four subsystems, which are: a couple of joined elements, a contact layer between the elements, and a set of bolts. The contact layer is assumed as the Winkler model, which can be treated as a nonlinear or linear model. In contrast, the set of bolts are modelled using simplified beam models, known as spider bolt models. The theorem according to which nonlinearity of the contact layer has a negligible impact on the final preload of the joint in the case of its sequential tightening has been verified. Results of sample calculations for the selected multi-bolted system, in the form of diagrams of preloads in the bolts as well as normal contact pressure between the joined elements during the assembly process and at its end, are presented.

Characteristics extraction and numerical analysis of the rough surface macro-morphology

2019 ◽  
Vol 36 (3) ◽  
pp. 765-780
Author(s):  
Qingchao Sun ◽  
Xiaokai Mu ◽  
Bo Yuan ◽  
Jiawen Xu ◽  
Wei Sun
Keyword(s):  
Surface Morphology ◽  
Contact Pressure ◽  
Contact Area ◽  
Contact Stiffness ◽  
Contact Model ◽  
Normal Contact ◽  
Content Type ◽  
Macro Scale ◽  
Machined Parts ◽  
Morphology Characteristics

PurposeThis paper aims to distinguish the relationship between the morphology characteristics of different scales and the contact performance of the mating surfaces. Also, an integrated method of the spectrum analysis and the wavelet transform is used to separate the morphology characteristics of the actual machined parts.Design/methodology/approachFirst, a three-dimensional (3D) surface profilometer is used to obtain the surface morphology data of the actual machined parts. Second, the morphology characteristics of different scales are realized by the wavelet analysis and the power spectral density. Third, the reverse modeling engineering is used to construct the 3D contact models for the macroscopic characteristics. Finally, the finite element method is used to analyze the contact stiffness and the contact area of the 3D contact model.FindingsThe contact area and the nominal contact pressure Pn have a nonlinear relationship in the whole compression process for the 3D contact model. The percentage of the total contact area of the macro-scale mating surface is about 70 per cent when the contact pressure Pn is in the range of 0-100 MPa, and the elastic contact area accounts for the vast majority. Meanwhile, when the contact pressure Pn is less than 10MPa, the influence factor (the relative error of contact stiffness) is larger than 50 per cent, so the surface macro-scale morphology has a weakening effect on the normal contact stiffness of the mating surfaces.Originality/valueThis paper provides an effective method for the multi-scale separation of the surface morphology and then lays a certain theoretical foundation for improving the surface quality of parts and the morphology design.

Contact Analysis for Joint Interfaces of Machine Tools Based on a 3-D Anisotropic Asperity Model

2011 ◽  
Vol 189-193 ◽  
pp. 114-120 ◽  
Author(s):  
Hai Tao Liu ◽  
Wan Hua Zhao ◽  
Jun Zhang
Keyword(s):  
Finite Element ◽  
Contact Pressure ◽  
Contact Stiffness ◽  
Contact Analysis ◽  
Joint Interface ◽  
Average Height ◽  
Exponential Relationship ◽  
Normal Contact ◽  
Normal Deformation ◽  
Normal Contact Pressure

In this paper, a 3-D contact model for anisotropic rough surfaces based on 3-D statistically measurements is established and finite element contact analysis is conducted. The average height of the asperity (h), the average summit distances between two neighboring peaks of asperities (Sx and Sy) are selected as the characterized parameters of the rough surface. Finite element simulation results show that the normal contact pressure has an exponential relation with the normal deformation and an exact linear relationship between the normal deformation and the real contact pressure of the surfaces is obtained. At last, the normal contact stiffness of the joint interface is obtained empirically with the exponential relationship assumption.

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