Validation of a Finite Element Humeroradial Joint Model of Contact Pressure Using Fuji Pressure Sensitive Film

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Sunghwan Kim ◽  
Mark Carl Miller
Keyword(s):  
Finite Element ◽  
Contact Stress ◽  
Contact Area ◽  
Axial Loads ◽  
Contact Areas ◽  
Pressure Sensitive ◽  
Maximum Contact Stress ◽  
Sensitive Film ◽  
Pressure Sensitive Film ◽  
Maximum Contact

A finite element (FE) elbow model was developed to predict the contact stress and contact area of the native humeroradial joint. The model was validated using Fuji pressure sensitive film with cadaveric elbows for which axial loads of 50, 100, and 200 N were applied through the radial head. Maximum contact stresses ranged from 1.7 to 4.32 MPa by FE predictions and from 1.34 to 3.84 MPa by pressure sensitive film measurement while contact areas extended from 39.33 to 77.86 mm2 and 29.73 to 83.34 mm2 by FE prediction and experimental measurement, respectively. Measurements from cadaveric testing and FE predictions showed the same patterns in both the maximum contact stress and contact area, as another demonstration of agreement. While measured contact pressures and contact areas validated the FE predictions, computed maximum stresses and contact area tended to overestimate the maximum contact stress and contact area.

Contact Stress and Linearized Modal Predictions of As-Built Preloaded Assembly

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Adam R. Brink ◽  
Robert J. Kuether ◽  
Matthew D. Fronk ◽  
Bryan L. Witt ◽  
Brendan L. Nation
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Contact Area ◽  
Element Model ◽  
High Fidelity ◽  
Vibration Modes ◽  
Low Level ◽  
Pressure Sensitive ◽  
Sensitive Film ◽  
Pressure Sensitive Film

Abstract The member stiffness and pressure distribution in a bolted joint is significantly influenced by the contact area of the mechanical interface under a prescribed preload force. This research explores the influence of as-built surface profiles for nominally flat interfaces of a C-Beam assembly with two well-defined contact regions. A high-fidelity finite element model is created such that the model uncertainty is minimized by updating and calibrating the piece parts prior to the preload assembly procedure. The model is then assembled and preloaded to evaluate the contact stresses and contact area for both nominally flat and perturbed non-flat surfaces based on three-dimensional surface topography measurements. The predicted pressures are validated with digitized pressure-sensitive film measurements. The high-fidelity modeling reveals how the compliance and thickness of the pressure-sensitive film alter the measured pressures, leading to incorrect evaluations of the stresses and contact area in the joint. The resulting low-level dynamic behavior of the preloaded assembly is shown to be sensitive to the true contact area by linearizing the nonlinear finite element model about the preloaded equilibrium and performing a computational modal analysis. The resonant frequencies are validated with experimental measurements to demonstrate the effect of the contact area on the modal characteristics of the bolted assembly. Vibration modes and loading patterns exhibit varying levels of sensitivity to the contact area in the joint, leading to an improved physical understanding of the influence of contact mechanics on the low-level linear vibration modes of jointed assemblies.

Assessment of Nominal Contact Area Parameters by Means of Ultrasonic Waves

2004 ◽  
Vol 126 (4) ◽  
pp. 639-645 ◽  
Author(s):  
Francesco Aymerich ◽  
Massimiliano Pau
Keyword(s):  
Contact Area ◽  
Ultrasonic Method ◽  
Ultrasonic Waves ◽  
Contact Interface ◽  
Ultrasonic Beam ◽  
Pressure Sensitive ◽  
Sensitive Film ◽  
Pressure Sensitive Film ◽  
Blurring Effect ◽  
Nominal Contact Area

In this paper the application of an ultrasonic method to evaluate size and shape of the nominal contact area between two contacting bodies is studied. The technique is based on the analysis of the quota of the ultrasonic wave reflected by the interface, which may be related to the level of contact between the surfaces. A simple deconvolution procedure is applied to the raw ultrasonic data so as to remove the blurring effect introduced by the ultrasonic beam size. The ultrasonic data acquired on a simple sphere-plane contact interface are compared with those obtained by means of a commercial pressure sensitive film and the results are discussed to evaluate the capability of the ultrasonic technique to capture the main contact patch features correctly.

The Effects of Load on the Radial Bearing Properties of Pre-Loaded Cylindrical Roller Bearings

2011 ◽  
Vol 130-134 ◽  
pp. 2306-2310
Author(s):  
Yan Gang Wei ◽  
Meng Sun
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Contact Stress ◽  
Radial Load ◽  
The Finite Element Method ◽  
Roller Bearings ◽  
Radial Stiffness ◽  
Maximum Contact Stress ◽  
Maximum Contact ◽  
Cylindrical Roller

According to the theory of contact mechanics, the radial stiffness, the maximum contact stress, and the maximum radial load of pre-loaded cylindrical roller bearings, including both solid roller and hollow roller bearings, are calculated with the finite element method. The effects of load on the radial stiffness, the maximum contact stress, and the maximum radial load of bearing are analyzed. The analysis results show that the effect of load on the radial stiffness is complex. Under the different magnitude loads, the effects of both hollowness and interference magnitude on the radial stiffness and on the maximum contact stress are not same. Thus the effects of load magnitude must be considered in the design and application of pre-loaded cylindrical roller bearings.

scholarly journals A New Sensor for Measurement of Dynamic Contact Stress in the Hip

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
M. J. Rudert ◽  
B. J. Ellis ◽  
C. R. Henak ◽  
N. J. Stroud ◽  
D. R. Pederson ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Contact Stress ◽  
Dynamic Contact ◽  
Contact Stresses ◽  
Heel Strike ◽  
Hip Joints ◽  
Pressure Sensitive ◽  
Sensitive Film ◽  
Load Cells ◽  
Pressure Sensitive Film

Various techniques exist for quantifying articular contact stress distributions, an important class of measurements in the field of orthopaedic biomechanics. In situations where the need for dynamic recording has been paramount, the approach of preference has involved thin-sheet multiplexed grid-array transducers. To date, these sensors have been used to study contact stresses in the knee, shoulder, ankle, wrist, and spinal facet joints. Until now, however, no such sensor had been available for the human hip joint due to difficulties posed by the deep, bi-curvilinear geometry of the acetabulum. We report here the design and development of a novel sensor capable of measuring dynamic contact stress in human cadaveric hip joints (maximum contact stress of 20 MPa and maximum sampling rate 100 readings/s). Particular emphasis is placed on issues concerning calibration, and on the effect of joint curvature on the sensor's performance. The active pressure-sensing regions of the sensors have the shape of a segment of an annulus with a 150-deg circumferential span, and employ a polar/circumferential “ring-and-spoke” sensel grid layout. There are two sensor sizes, having outside radii of 44 and 48 mm, respectively. The new design was evaluated in human cadaver hip joints using two methods. The stress magnitudes and spatial distribution measured by the sensor were compared to contact stresses measured by pressure sensitive film during static loading conditions that simulated heel strike during walking and stair climbing. Additionally, the forces obtained by spatial integration of the sensor contact stresses were compared to the forces measured by load cells during the static simulations and for loading applied by a dynamic hip simulator. Stress magnitudes and spatial distribution patterns obtained from the sensor versus from pressure sensitive film exhibited good agreement. The joint forces obtained during both static and dynamic loading were within ±10% and ±26%, respectively, of the forces measured by the load cells. These results provide confidence in the measurements obtained by the sensor. The new sensor's real-time output and dynamic measurement capabilities hold significant advantages over static measurements from pressure sensitive film.

Sealing performance and fatigue life of the fracturing packer rubber of various materials

2019 ◽  
Vol 233 (17) ◽  
pp. 6157-6166 ◽  
Author(s):  
Fuying Zhang ◽  
Haoche Shui ◽  
Jun-Mei Yang
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Contact Stress ◽  
Field Experiments ◽  
Structural Parameters ◽  
Element Model ◽  
Rubber Seal ◽  
Maximum Contact Stress ◽  
Different Temperatures ◽  
Maximum Contact

The finite element model of four packer rubber materials was established by using ABAQUS and FE-SAFE software. The initial sealing load (the load is the pressure) was 11.85 MPa, and the working load was 58.15 MPa. The sealing evaluation coefficient, maximum contact stress, and fatigue life value of four material packer rubbers were considered when considering temperature changes and fatigue unit nodes. The results show that when the working load and the structural parameters of the rubber are the same, the sealing evaluation coefficient of the four material rubber increases with the increase of temperature. When the working temperature reaches 125 ℃, the value of the rubber seal evaluation coefficient of the HNBR material is the largest, and the value of the rubber seal evaluation coefficient of the EPDM material is the smallest. Similarly, the maximum contact stress of the four material rubbers increases with increasing temperature. When the temperature reaches 125 ℃, the maximum contact stress of the HNBR material is the largest, and the maximum contact stress of the EPDM material is the smallest. The rubber of the four materials increase the fatigue life value with the increase in the temperature within the operating temperature range studied. When the temperature is lower than 120 ℃, the fatigue life value of the HNBR material rubber is the largest. When the temperature is higher than 120 ℃, the fatigue life value of the CR material rubber is the largest. Regardless of the temperature change, the fatigue life value of the EPDM is the smallest. By comparing the results of field experiments with the results of finite element models, the two are found to have good consistency, which verifies the validity and feasibility of the model. The research results have important guiding significance for the fatigue life prediction of various material packer rubbers under different temperatures.

Customized surface-guided knee implant: Contact analysis and experimental test

2017 ◽  
Vol 232 (1) ◽  
pp. 90-100 ◽  
Author(s):  
Ida Khosravipour ◽  
Shabnam Pejhan ◽  
Yunhua Luo ◽  
Urs P Wyss
Keyword(s):  
Molecular Weight ◽  
Finite Element ◽  
High Molecular Weight ◽  
Contact Pressure ◽  
Element Analysis ◽  
Pressure Sensitive ◽  
Sensitive Film ◽  
Pressure Sensitive Film ◽  
Total Knee ◽  
Ultra High Molecular Weight

Contact pressure and stresses on the articulating surface of the tibial component of a total knee replacement are directly related to the joint contact forces and the contact area. These stresses can result in wear and fatigue damage of the ultra-high-molecular-weight polyethylene. Therefore, conducting stress analysis on a newly designed surface-guided knee implant is necessary to evaluate the design with respect to the polyethylene wear. Finite element modeling is used to analyze the design’s performance in level walking, stair ascending and squatting. Two different constitutive material models have been used for the tibia component to evaluate the effect of material properties on the stress distribution. The contact pressure results of the finite element analysis are compared with the results of contact pressure using pressure-sensitive film tests. In both analyses, the average contact pressure remains below the material limits of ultra-high-molecular-weight polyethylene insert. The peak von Mises stresses in 90° of flexion and 120° of flexion (squatting) are 16.28 and 29.55 MPa, respectively. All the peak stresses are less than the fatigue failure limit of ultra-high-molecular-weight polyethylene which is 32 MPa. The average contact pressure during 90° and 120° of flexion in squatting are 5.51 and 5.46 MPa according to finite element analysis and 5.67 and 8.14 MPa according to pressure-sensitive film experiment. Surface-guided knee implants are aimed to resolve the limitations in activities of daily living after total knee replacement by providing close to normal kinematics. The proposed knee implant model provides patterns of motion much closer to the natural target, especially as the knee flexes to higher degrees during squatting.

Repeatability and contact stress gradient detection of sealed pressure-sensitive film when used in a physiological joint model

2008 ◽  
Vol 222 (7) ◽  
pp. 1065-1071
Author(s):  
G A Matricali ◽  
L Labey ◽  
W Bartels ◽  
G Dereymaeker ◽  
F P Luyten ◽  
...  
Keyword(s):  
Contact Stress ◽  
Coefficient Of Variation ◽  
Stress Gradient ◽  
Joint Model ◽  
Pressure Recording ◽  
Stress Gradients ◽  
Pressure Sensitive ◽  
Sensitive Film ◽  
Custom Made ◽  
Pressure Sensitive Film

Sealed pressure-sensitive film is frequently used to record contact characteristics in physiological joints. However, the effect on the pressure-recording characteristics of sealing the film when used in these circumstances has never been studied. This study compares the coefficient of variation, the standardized coefficient of variation, the tangent and secant contact stress gradients, and the actual pressures between unsealed and sealed Fuji film, in a simplified physiological joint model with a full-thickness surface defect. Unsealed film and sealed film were loaded through a range of nominal loads and the resulting stains were analysed by use of custom-made macros for the ImageJ image-processing program. The coefficient of variation did not exceed 5.7 per cent (sealed film), and the standardized coefficient of variation did not exceed 1.8 per cent (unsealed and sealed film). Contact stress gradients did not differ significantly. The recorded pressure at the level of surface defects was always about 0.2 MPa higher in the case of sealed film, and therefore predictable. It is concluded that sealing the film will not change the pressure-recording characteristics.

A Pressure Sensitive Film Study on the Effect of Screw Omission on Bone-plate Interface Mechanics in Cadaveric Bone

1997 ◽  
Vol 10 (04) ◽  
pp. 205-209 ◽  
Author(s):  
T. C. Hearn ◽  
C. B. Caldwell ◽  
H. Tornkvist ◽  
J. R. Field
Keyword(s):  
Contact Area ◽  
Bone Plate ◽  
Bone Strain ◽  
Average Force ◽  
Pressure Sensitive ◽  
Sensitive Film ◽  
Metacarpal Bones ◽  
Interface Mechanics ◽  
Pressure Sensitive Film ◽  
Interface Contact

SummaryMinimalising surgical exposure and the amount of hardware implanted has become the aim in promoting the biological healing of fractures. Increased spacing of fewer bone screws can increase the mechanical strength of fracture fixation without jeopardizing the stability of the construction. The omission of selective screws has also been shown to increase bone strain and has been suggested as a means of treating bone plate induced osteoporosis.Using Fuji prescale pressure sensitive film we evaluated the effect of selective screw omission on the platebone interface mechanics. Testing was performed using 10-hole, 4.5 mm DCP applied to equine cadaveric third metacarpal bones. Film was interposed between the bone and the bone plate which were applied to a constant level of screw torque. The resultant digitized bone plate patterns enabled computation of the interface contact area (%) and the average force (Newtons-N) at the interface and a qualitative assessment of the pattern of pressure distribution.The symmetrical omission of 40% of the total screw number resulted in significant differences between the control (10 screws) and each treatment for both interface contact area (p <0.05) and average force (p <0.02). In one pattern of screw omission there was a marginally non-significant difference between the control and treatment interface contact area (p = 0.0518).The results suggest that a dramatic reduction in the number of screws applied to a given plate (40%) evokes significant changes in the interface mechanics. Of interest is the effect the pattern of screw omission had on the interface mechanical features; certain screw omission patterns induced a reduction in contact area and force of the same magnitude as the number of screws omitted (40%), whilst in other patterns of screw omission the effect on interface mechanical features was much less than expected (20%).A number of implications can be postulated from these findings;1. Subsequent to the omission of screws the level interface friction may remain at a level sufficient as to not alter the ability of the fixation, to maintain fracture reduction and stability.2. The interface bone will benefit from a reduction in interface contact presumably resulting in less impairment to blood outflow through the cortex.3. The use of fewer screws in a given construction may augment the inherent bone strain.The effect on plate-bone interface mechanics of the symmetrical omission of screws was evaluated. This was accomplished using Fuji pressure sensitive film and provided an indication of interface contact area and average force. It was found that the omission of 40% of screws from a given plate significantly altered the interface contact area and the average force, however, the extent of these changes was influenced by the pattern of screw omission. This suggests that the selective omission of screws from a plate-bone construction may provide a means of limiting plate-induced osteopaenia during fracture healing, through a reduction in contact area and improved inherent bone strain.

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