Comparison of finite element and experimental contact pressures in the human hip joint under physiological loading

Joint injuries and the resulting posttraumatic osteoarthritis (OA) are a significant problem. There is still a need for tools to evaluate joint injuries, their effect on joint mechanics, and the relationship between altered mechanics and OA. Better understanding of injuries and their relationship to OA may aid in the development or refinement of treatment methods. This may be partially achieved by monitoring changes in joint mechanics that are a direct consequence of injury. Techniques such as image-based finite element modeling can provide in vivo joint mechanics data but can also be laborious and computationally expensive. Alternate modeling techniques that can provide similar results in a computationally efficient manner are an attractive prospect. It is likely possible to estimate risk of OA due to injury from surface contact mechanics data alone. The objective of this study was to compare joint contact mechanics from image-based surface contact modeling (SCM) and finite element modeling (FEM) in normal, injured (scapholunate ligament tear), and surgically repaired radiocarpal joints. Since FEM is accepted as the gold standard to evaluate joint contact stresses, our assumption was that results obtained using this method would accurately represent the true value. Magnetic resonance images (MRI) of the normal, injured, and postoperative wrists of three subjects were acquired when relaxed and during functional grasp. Surface and volumetric models of the radiolunate and radioscaphoid articulations were constructed from the relaxed images for SCM and FEM analyses, respectively. Kinematic boundary conditions were acquired from image registration between the relaxed and grasp images. For the SCM technique, a linear contact relationship was used to estimate contact outcomes based on interactions of the rigid articular surfaces in contact. For FEM, a pressure-overclosure relationship was used to estimate outcomes based on deformable body contact interactions. The SCM technique was able to evaluate variations in contact outcomes arising from scapholunate ligament injury and also the effects of surgical repair, with similar accuracy to the FEM gold standard. At least 80% of contact forces, peak contact pressures, mean contact pressures and contact areas from SCM were within 10 N, 0.5 MPa, 0.2 MPa, and 15 mm2, respectively, of the results from FEM, regardless of the state of the wrist. Depending on the application, the MRI-based SCM technique has the potential to provide clinically relevant subject-specific results in a computationally efficient manner compared to FEM.

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

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.268-270.737 ◽

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.

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On the receding contact between a graded and a homogeneous layer due to a flat-ended indenter

Mathematics and Mechanics of Solids ◽

10.1177/10812865211043152 ◽

2021 ◽

pp. 108128652110431

Author(s):

Rui Cao ◽

Changwen Mi

Keyword(s):

Finite Element ◽

Contact Problem ◽

Integral Equations ◽

Singular Integral ◽

Functional Dependence ◽

Singular Integral Equations ◽

Homogeneous Layer ◽

Cauchy Type ◽

Receding Contact ◽

Contact Pressures

This paper solves the frictionless receding contact problem between a graded and a homogeneous elastic layer due to a flat-ended rigid indenter. Although its Poisson’s ratio is kept as a constant, the shear modulus in the graded layer is assumed to exponentially vary along the thickness direction. The primary goal of this study is to investigate the functional dependence of both contact pressures and the extent of receding contact on the mechanical and geometric properties. For verification and validation purposes, both theoretical analysis and finite element modelings are conducted. In the analytical formulation, governing equations and boundary conditions of the double contact problem are converted into dual singular integral equations of Cauchy type with the help of Fourier integral transforms. In view of the drastically different singularity behavior of the stationary and receding contact pressures, Gauss–Chebyshev quadratures and collocations of both the first and the second kinds have to be jointly used to transform the dual singular integral equations into an algebraic system. As the resultant algebraic equations are nonlinear with respect to the extent of receding contact, an iterative algorithm based on the method of steepest descent is further developed. The semianalytical results are extensively verified and validated with those obtained from the graded finite element method, whose implementation details are also given for easy reference. Results from both approaches reveal that the property gradation, indenter width, and thickness ratio all play significant roles in the determination of both contact pressures and the receding contact extent. An appropriate combination of these parameters is able to tailor the double contact properties as desired.

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Modeling the HSK Toolholder-Spindle Interface

Journal of Manufacturing Science and Engineering ◽

10.1115/1.1480023 ◽

2002 ◽

Vol 124 (3) ◽

pp. 734-744 ◽

Cited By ~ 14

Author(s):

Ihab M. Hanna ◽

John S. Agapiou ◽

David A. Stephenson

Keyword(s):

Finite Element ◽

Material Properties ◽

System Reliability ◽

High Volume ◽

Finite Element Models ◽

Operational Experience ◽

Bending Load ◽

Load Carrying ◽

Detailed Evaluation ◽

Contact Pressures

The HSK toolholder-spindle connection was developed to overcome shortcomings of the 7/24 steep-taper interface, especially at higher speeds. However, the HSK system was standardized quickly, without detailed evaluation based on operational experience. Several issues concerning the reliability, maintainability, and safety of the interface have been raised within the international engineering community. This study was undertaken to analytically investigate factors which influence the performance and limitations of the HSK toolholder system. Finite Element Models were created to analyze the effects of varying toolholder and spindle taper geometry, axial spindle taper length, drawbar/clamping load, spindle speed, applied bending load, and applied torsional load on HSK toolholders. Outputs considered include taper-to-taper contact pressures, taper-to-taper clearances, minimum drawbar forces, interface stiffnesses, and stresses in the toolholder. Static deflections at the end of the holder predicted by the models agreed well with measured values. The results showed that the interface stiffness and load-carrying capability are significantly affected by taper mismatch and dimensional variations, and that stresses in the toolholder near the drive slots can be quite high, leading to potential fatigue issues for smaller toolholders subjected to frequent clamping-unclamping cycles (e.g., in high volume applications). The results can be used to specify minimum toolholder material properties for critical applications, as well as drawbar design and spindle/toolholder gaging guidelines to increase system reliability and maintainability.

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AN ALGORITHM TO CALCULATE THE COMPONENTS OF ALL MUSCLE FORCES DURING EACH PHASES OF THE GAIT CYCLE, FOR THE PELVIC-FEMUR COMPLEX

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519405001680 ◽

2005 ◽

Vol 05 (04) ◽

pp. 539-548 ◽

Cited By ~ 1

Author(s):

SANTANU MAJUMDER ◽

AMIT ROYCHOWDHURY ◽

SUBRATA PAL

Keyword(s):

Finite Element ◽

Hip Joint ◽

Computational Models ◽

Gait Cycle ◽

Muscle Force ◽

Fe Analysis ◽

Muscle Forces ◽

Force Magnitude ◽

Flexion Extension ◽

Force Components

With the help of finite element (FE) computational models of femur, pelvis or hip joint to perform quasi-static stress analysis during the entire gait cycle, muscle force components (X, Y, Z) acting on the hip joint and pelvis are to be known. Most of the investigators have presented only the net muscle force magnitude during gait. However, for the FE software, either muscle force components (X, Y, Z) or three angles for the muscle line of action are required as input. No published algorithm (with flowchart) is readily available to calculate the required muscle force components for FE analysis. As the femur rotates about the hip center during gait, the lines of action for 27 muscle forces are also variable. To find out the variable lines of action and muscle force components (X, Y, Z) with directions, an algorithm was developed and presented here with detailed flowchart. We considered the varying angles of adduction/abduction, flexion/extension during gait. This computer program, obtainable from the first author, is able to calculate the muscle force components (X, Y, Z) as output, if the net magnitude of muscle force, hip joint orientations during gait and muscle origin and insertion coordinates are provided as input.

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Can the Hip Joint be Modeled Accurately Using Simplified Geometry?

ASME 2008 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2008-192902 ◽

2008 ◽

Author(s):

Andrew E. Anderson ◽

Steve A. Maas ◽

Benjamin J. Ellis ◽

Jeffrey A. Weiss

Keyword(s):

Contact Pressure ◽

Hip Joint ◽

Spherical Geometry ◽

Model Complexity ◽

Hip Morphology ◽

Joint Contact ◽

Analytical Approaches ◽

Contact Pressures ◽

In Vitro Data

Simplified analytical approaches to estimate hip joint contact pressures using perfectly spherical geometry have been described in the literature (rigid body spring models); however, estimations based on these simulations have not corresponded well with experimental in vitro data. Recent evidence from our laboratory suggests that finite element (FE) models of the hip joint that incorporate detailed geometry for cartilage and bone can predict cartilage pressures in good agreement with experimental data [1]. However, it is unknown whether this degree of model complexity is necessary. The objective of this study was to compare cartilage contact pressure predictions from FE models with varying degrees of simplicity to elucidate which aspects of hip morphology are required to obtain accurate predictions of cartilage contact pressure. Models based on 1) subject-specific (SS) geometry, 2) spheres, and 3) rotational conchoids were analyzed.

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507 Finite Element Modeling about the function of the hip joint

The Proceedings of Conference of Hokkaido Branch ◽

10.1299/jsmehokkaido.2008.47.125 ◽

2008 ◽

Vol 2008.47 (0) ◽

pp. 125-126

Author(s):

Tetsuya OHASHI ◽

Michihiro SATO ◽

Yasushi MIYAMOTO

Keyword(s):

Finite Element ◽

Finite Element Modeling ◽

Hip Joint ◽

Element Modeling

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Modeling the HSK (Hollow Shank Taper 1/10 Tapered Joint) Toolholder-Spindle Interface

10.1115/imece2000-1898 ◽

2000 ◽

Author(s):

Ihab M. Hanna ◽

John S. Agapiou ◽

David A. Stephenson

Keyword(s):

Finite Element ◽

Material Properties ◽

System Reliability ◽

High Volume ◽

Finite Element Models ◽

Operational Experience ◽

Bending Load ◽

Load Carrying ◽

Detailed Evaluation ◽

Contact Pressures

Abstract The HSK toolholder-spindle connection was developed to overcome shortcomings of the 7/24 steep-taper interface, especially at higher speeds. However, the HSK system was standardized quickly, without detailed evaluation based on operational experience. Several issues concerning the reliability, maintainability, and safety of the interface have been raised within the international engineering community. This study was undertaken to analytically investigate factors which influence the performance and limitations of the HSK toolholder system. Finite Element Models were created to analyze the effects of varying toolholder and spindle taper geometry, axial spindle taper length, drawbar/clamping load, spindle speed, applied bending load, and applied torsional load on HSK toolholders. Outputs considered include taper-to-taper contact pressures, taper-to-taper clearances, minimum drawbar forces, interface stiffnesses, and stresses in the toolholder. Static deflections at the end of the holder predicted by the models agreed well with measured values. The results showed that the interface stiffness and load-carrying capability are significantly affected by taper mismatch and dimensional variations, and that stresses in the toolholder near the drive slots can be quite high, leading to potential fatigue issues for smaller toolholders subjected to frequent clamping-unclamping cycles (e.g., in high volume applications). The results can be used to specify minimum toolholder material properties for critical applications, as well as drawbar design and spindle/toolholder gaging guidelines to increase system reliability and maintainability.

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