scholarly journals Assessment of Contact Pressures between a Mandibular Overdenture and the Prosthodontic Area

2021 ◽  
Vol 11 (10) ◽  
pp. 4339
Author(s):  
Małgorzata Idzior-Haufa ◽  
Agnieszka A. Pilarska ◽  
Tomasz Gajewski ◽  
Krzysztof Szajek ◽  
Łukasz Faściszewski ◽  
...  
Keyword(s):  
Contact Pressure ◽  
Applied Load ◽  
Critical Case ◽  
Matrix Stiffness ◽  
3D Scanner ◽  
Edentulous Mandible ◽  
Polypropylene Matrix ◽  
Mandibular Overdenture ◽  
Maximum Contact ◽  
Contact Pressures

In this paper, we assess the pressure between the overdenture located in the mandible and supported by a bar retained on two implants and the prosthodontic area. For testing, a model of an edentulous mandible was created using a mold by FRASACO with two implants and a “rider” bar inserted. A complete mandibular denture with polypropylene matrices was made. Three types of matrices of various stiffness were applied. The mandible and overdenture geometry was mapped using a digital image obtained with a Steinbichler Comet L3D 3D scanner. Finite element method calculations were performed in the Abaqus FEA software. The results demonstrate that the maximum contact pressure is observed when the loads are associated with canines. A critical case for the lower posterior is chewing performed by the molars. The pressure zone is the largest for POM-1 with Young’s modulus of 1.5 GPa and is reduced by 5.0% and 7.8% for POM-2 (E = 2.5 GPa) and POM-3 (E = 3.5 GPa), respectively. The stress distribution under the prosthesis mostly depends on the region loaded onto it. The applied load produces a slight contact pressure between the denture and the prosthodontic area in the anterior zone. A change in polypropylene matrix stiffness does not affect contact pressures.

Analysis and Comparison of Seal Ability of Premium Tubing Connections under Axial Alternating Load

2013 ◽  
Vol 423-426 ◽  
pp. 2035-2039
Author(s):  
Long Cang Huang ◽  
Yin Ping Cao ◽  
Yang Yu ◽  
Yi Hua Dou
Keyword(s):  
Contact Pressure ◽  
Oil And Gas ◽  
Element Analysis ◽  
Gas Well ◽  
Cycle Number ◽  
Compression Load ◽  
Well Production ◽  
Maximum Contact ◽  
Contact Pressures ◽  
Better Than

In the process of oil and gas well production, tubing connection stand the axial alternating load during open well, shut well and fluid flow. In order to know premium connection seal ability under the loading, two types of P110 88.9mmx6.45mm premium tubing connections which called A connection and B connection are performed with finite element analysis, in which contact pressures and their the regularities distribution on sealing surface are analyzed. The results show that with the increasing of cycle number, the maximum contact pressures on sealing surface of both A connection and B connection are decreased. The decreasing of the maximum contact pressures on B connection is greater than those on A connection. With the increasing of cycle number of axial alternating compression load, the maximum contact pressure on sealing surface of A connection is decreased, and the maximum contact pressure on sealing surface of B connection remains constant. Compared the result, it shows that the seal ability of A connection is better than B connection under axial alternating tension load, while the seal ability of B connection is better than type A connection under axial alternating compression load.

Analysis of Premium Connection of Connecting and Sealing Ability Loaded by Axial Tensile Loads

2012 ◽  
Vol 268-270 ◽  
pp. 737-740
Author(s):  
Yang Yu ◽  
Yi Hua Dou ◽  
Fu Xiang Zhang ◽  
Xiang Tong Yang
Keyword(s):  
Finite Element ◽  
Contact Pressure ◽  
Tensile Load ◽  
Element Model ◽  
Sealing Ability ◽  
Axial Tensile ◽  
High Level ◽  
Maximum Contact ◽  
Contact Pressures ◽  
The Finite Element Model

It is necessary to know the connecting and sealing ability of premium connection for appropriate choices of different working conditions. By finite element method, the finite element model of premium connection is established and the stresses of seal section, shoulder zone and thread surface of tubing by axial tensile loads are analyzed. The results show that shoulder zone is subject to most axial stresses at made-up state, which will make distribution of stresses on thread reasonable. With the increase of axial tensile loads, stresses of thread on both ends increase and on seal section and shoulder zone slightly change. The maximum stress on some thread exceed the yield limit of material when axial tensile loads exceed 400KN. Limited axial tensile loads sharply influence the contact pressures on shoulder zone while slightly on seal section. Although the maximum contact pressure on shoulder zone drop to 0 when the axial tensile load is 600KN, the maximum contact pressure on seal section will keep on a high level.

Central and Minimum Elastohydrodynamic Film Thickness at High Contact Pressure

1997 ◽  
Vol 119 (2) ◽  
pp. 291-296 ◽  
Author(s):  
M. Smeeth ◽  
H. A. Spikes
Keyword(s):  
High Pressure ◽  
Film Thickness ◽  
Contact Pressure ◽  
Applied Load ◽  
Optical Technique ◽  
Test Rig ◽  
Minimum Film Thickness ◽  
Elastohydrodynamic Film Thickness ◽  
Contact Pressures ◽  
High Contact Pressure

A new optical technique has been developed which is able to obtain accurate film thickness profiles across elastohydrodynamic (EHD) contacts. This has been used in conjunction with a high pressure EHD test rig to obtain both central and minimum EHD film thicknesses at high contact pressures up to 3.5 GPa. The results have been compared with the classical film thickness equations of Hamrock and Dowson and also with recent high pressure computations due to Venner. It is found that minimum film thickness falls more rapidly with applied load at high than at low contact pressures, with a film thickness/load exponent of −0.3. This confirms the findings of recent high pressure computational EHD modeling.

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.

Effects of Rolling Speed and Reduction on Rolling Simulation Results of Monolithic Fuel Plates

2018 ◽  
Vol 19 (6) ◽  
pp. 605-619
Author(s):  
Xiangzhe Kong ◽  
Hongyan Yang ◽  
Shurong Ding ◽  
Xiaoming Peng
Keyword(s):  
Contact Pressure ◽  
Nuclear Fuel ◽  
Three Dimensional ◽  
Fem Simulation ◽  
Rolling Speed ◽  
Geometrical Shape ◽  
Dog Bone ◽  
Interface Bonding Strength ◽  
Maximum Contact ◽  
Contact Pressures

AbstractThe in-pile performances of UMo/Zr monolithic nuclear fuel plates are directly related to their manufacturing quality. The interface bonding strength depends on the contact pressures over the surfaces of the Zircaloy covers, the Zircaloy frame and the UMo coupon during rolling. The contact pressures are affected by the process parameters such as the rolling speed and the reduction per pass. These parameters should be carefully investigated to optimize the fabrication process. In this study, a three-dimensional stress updating algorithm is presented for the strain-rate-dependent mechanical constitutive relation of Zircaloy. Three-dimensional FEM simulation of the rolling process for monolithic nuclear fuel plates is carried out. The influences of the rolling speed and reduction on the geometrical shape and the contact pressure between the Zircaloy cover and the coupon will be discussed according to the computational results. The results indicate that (1) along the plate width direction the maximum contact pressure between the coupon and the Zircaloy cover exists at the center and decreases towards the edge; (2) when the rolling speed or reduction increases, the maximum contact pressure increases as well; and the dog-bone shape of the coupon at the back end is more visible.

Contact Pressure Sensitivity Analysis in N95 Filtering Facepiece Respirator With Strap Location, Friction, and Headform Material Property

2015 ◽  
Author(s):  
Ming Xu ◽  
James Yang
Keyword(s):  
Finite Element ◽  
Soft Tissue ◽  
Pressure Distribution ◽  
Contact Pressure ◽  
Material Property ◽  
Sensitivity Study ◽  
Facial Soft Tissue ◽  
Maximum Contact ◽  
Contact Pressures ◽  
Tissue Material

The contact pressure between an N95 filtering facepiece respirator (FFR) and the human face plays an important role in FFR performance. In this paper, the effects of several important factors (strap locations on headback, friction, and facial soft tissue material property) on contact pressures are studied using validated N95 FFR/headform finite element models. Sixteen different FFR/headform combinations including six FFRs and five digital headforms (small, medium, large, long/narrow, and short/wide) are studied. For each FFR/headform combination, the facial contact pressure distribution is recorded from the finite element results. The maximum contact pressures from six key areas are recorded for sensitivity study. The results show that the strap locations on the headback produce the largest effect on the maximum contact pressure values and the pressure distribution. The friction and the facial soft tissue material property have limited effects on the maximum contact pressure although they can affect the pressure distribution.

Paper 18: Effect of Interface Geometry on the Wear of Graphite Sliding against Stainless Steel

1966 ◽  
Vol 181 (15) ◽  
pp. 11-15
Author(s):  
J. E. Houghton ◽  
L. A. Mitchell ◽  
T. S. Crawford
Keyword(s):  
Stainless Steel ◽  
Brittle Fracture ◽  
Wear Rate ◽  
Contact Pressure ◽  
Graphite Surface ◽  
Specific Wear Rate ◽  
Maximum Contact ◽  
Contact Pressures ◽  
Very High ◽  
Interface Geometry

The specific wear rate of reactor-grade graphite discs, sliding against En 58B stainless-steel cylinders, was determined for a range of theoretical contact pressures for unidirectional, constant-speed sliding in laboratory air. In many instances, wear was found to be discontinuous and associated with blistering of the graphite surface; the severity of blistering increased with increasing maximum contact pressure, but became negligible at low contact pressures, when the specific wear rate tended to a constant value—the microscopic component. At very high contact pressures, wear resulted predominantly from ploughing, i.e. instantaneous brittle fracture.

Maximum Interlabial Pressures in Normal Speakers

1997 ◽  
Vol 40 (2) ◽  
pp. 400-404 ◽  
Author(s):  
Virginia A. Hinton ◽  
Winston M. C. Arokiasamy
Keyword(s):  
Speech Production ◽  
Contact Pressure ◽  
Direct Evidence ◽  
Unit Area ◽  
Jaw Movement ◽  
Contractile Forces ◽  
Contact Pressures ◽  
Muscle Contractile

It has been hypothesized that typical speech movements do not involve large muscular forces and that normal speakers use less than 20% of the maximum orofacial muscle contractile forces that are available (e.g., Amerman, 1993; Barlow & Abbs, 1984; Barlow & Netsell, 1986; DePaul & Brooks, 1993). However, no direct evidence for this hypothesis has been provided. This study investigated the percentage of maximum interlabial contact pressures (force per unit area) typically used during speech production. The primary conclusion of this study is that normal speakers typically use less than 20% of the available interlabial contact pressure, whether or not the jaw contributes to bilabial closure. Production of the phone [p] at conversational rate and intensity generated an average of 10.56% of maximum available interlabial pressure (MILP) when jaw movement was not restricted and 14.62% when jaw movement was eliminated.

Experimental and Theoretical Study of the Contact Mechanics of Five Total Knee Joint Replacements

1995 ◽  
Vol 209 (4) ◽  
pp. 225-231 ◽  
Author(s):  
T Stewart ◽  
Z M Jin ◽  
D Shaw ◽  
D D Auger ◽  
M Stone ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Knee Joint ◽  
Contact Pressure ◽  
Contact Stress ◽  
Linear Elasticity ◽  
Contact Area ◽  
Elasticity Analysis ◽  
Joint Replacements ◽  
Total Knee ◽  
Maximum Contact

The tibio-femoral contact area in five current popular total knee joint replacements has been measured using pressure-sensitive film under a normal load of 2.5 kN and at several angles of flexion The corresponding maximum contact pressure has been estimated from the measured contact areas and found to exceed the point at which plastic deformation is expected in the ultra-high molecular weight polyethylene (UHMWPE) component particularly at flexion angles near 90°. The measured contact area and the estimated maximum contact stress have been found to be similar in magnitude for all of the five knee joint replacements tested. A significant difference, however, has been found in maximum contact pressure predicted from linear elasticity analysis for the different knee joints. This indicates that varying amounts of plastic deformation occurred in the polyethylene component in the different knee designs. It is important to know the extent of damage as knees with large amounts of plastic deformation are more likely to suffer low cycle fatigue failure. It is therefore concluded that the measurement of contact areas alone can be misleading in the design of and deformation in total knee joint replacements. It is important to modify geometries to reduce the maximum contact stress as predicted from the linear elasticity analysis, to below the linear elastic limit of the plastic component.

Effect of load type on temperature rise of a disc brake

2014 ◽  
Vol 5 (1) ◽  
pp. 30-44 ◽  
Author(s):  
Qing-rui Meng
Keyword(s):  
Contact Pressure ◽  
Temperature Rise ◽  
Axial Direction ◽  
Sine Wave ◽  
Practical Application ◽  
Ansys Software ◽  
Content Type ◽  
Load Types ◽  
Load Simulation ◽  
Contact Pressures

Purpose – The purpose of this paper is to reveal the temperature rise characteristics of the disc and pads under different load types. Design/methodology/approach – Evolutions of the disc and pads temperature under a stable, gradual changing and sine-wave contact pressures widely used at present are analyzed numerically by using ANSYS software. Findings – The results show that during the loading process, the temperature increases most rapidly under a stable contact pressure, most slowly under a gradual changing contact pressure; the disc temperature rise curves expose saw-shaped character, the closer it is to the friction surface, the more serious the fluctuations will be, the pads temperature rise curves are rather smooth; temperature gradient in the axial direction is higher than that in the other two directions under all of the three types of contact pressure and shows a sine-wave variation under a sine-wave contact pressure. Originality/value – It indicates that a gradual changing contact pressure should be adopted preferentially in practical application. The simulation results of this work provide theoretical basis for load simulation.

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