Numerical Convergence in Wear Volume Prediction of UHMWPE Acetabular Cup Paired with cp Ti Femoral Head Hip Implants

2020 ◽  
Vol 867 ◽  
pp. 148-158
Author(s):  
Handoko ◽  
Suyitno ◽  
Dharmastiti Rini ◽  
Rahadyan Magetsari
Keyword(s):  
Femoral Head ◽  
Pure Titanium ◽  
Computational Method ◽  
Wear Volume ◽  
Hip Implants ◽  
Acetabular Cup ◽  
Wear Factor ◽  
Numerical Convergence ◽  
Load Increment ◽  
Cp Ti

Wear is a problem for metal on polymer (MOP) hip implants to perform lifetime endurance. Polymer excessive volumetric loss leads to implant failures. Attempts to solve this problem are usually initiated with tribological tests. The method is time-consuming because the sliding speed is low. There is a faster way to use a computational method to gather wear data. This research aims to investigate the numerical convergence of predicted wear volume with the finite element method (FEM). The model is a commercially pure titanium (cp Ti) and ultra-high molecular weight polyethylene (UHMWPE) MOP hip implant. A dynamic Paul physiological load was applied to the model. Volumetric loss of the polymer was calculated with a wear equation involved nonlinear contact load and contact area. The inputs of calculation are wear factor and the computational contact mechanic performed by FEM. The wear factor was obtained by performing biotribological experiments with a multidirectional pin on disc tribotest. Predicted wear volume was validated with hip simulator experimental data from the literature. Convergences were found at the mesh density of 1.38 elements/mm3. An acceptable numerical error was obtained in the model with 1 mm element size for femoral head and 0.3 mm for acetabular cup. This model was then used for the investigation of load increment effects. The result is that load increment variations do not affect wear volume and contact mechanic numerical outputs. The calculated stresses are below the UHMWPE yield stress limit. In this elastic region, the effects of strain rate caused by load increment are negligible.

Analysis of contact mechanics in ceramic-on-ceramic hip joint replacements

2002 ◽  
Vol 216 (4) ◽  
pp. 231-236 ◽  
Author(s):  
M M Mak ◽  
Z M Jin
Keyword(s):  
Femoral Head ◽  
Contact Mechanics ◽  
Contact Pressure ◽  
Contact Area ◽  
Design Parameters ◽  
Radial Clearance ◽  
Hip Implants ◽  
Acetabular Cup ◽  
Ceramic Insert ◽  
Ceramic On Ceramic

The contact mechanics in ceramic-on-ceramic hip implants has been analysed in this study using the finite element method. Only the ideal conditions where the contact occurs within the acetabular cup were considered. It has been shown that the contact pressure distribution and the contact area at the main articulating bearing surfaces depend largely on design parameters such as the radial clearance between the femoral head and the acetabular cup, as well as the thickness of the ceramic insert. For the ceramic-on-ceramic hip implants used in clinics today, with a minimum 5-mm-thick ceramic insert, it has been shown that the radius of the contact area between the femoral head and the acetabular cup is relatively small compared with that of the femoral head and the ceramic insert thickness. Consequently, Hertz contact theory can be used to estimate the contact parameters such as the maximum contact pressure and the contact area.

scholarly journals Analysis of Relative Motion between Femoral Head and Acetabular Cup and Advances in Computation of the Wear Factor for the Prosthetic Hip Joint

10.14311/454 ◽  
2003 ◽  
Vol 43 (4) ◽  
Author(s):  
O. Calonius ◽  
V. Saikko
Keyword(s):  
Femoral Head ◽  
Pressure Distribution ◽  
Contact Force ◽  
Relative Motion ◽  
Hip Joint ◽  
Contact Pressure Distribution ◽  
Acetabular Cup ◽  
Wear Factor ◽  
Walking Motion ◽  
Sliding Distance

The amount and type of wear produced in the prosthetic hip joint depends on the type of relative motion between the femoral head and the acetabular cup. Wear particles removed from the bearing surfaces of the joint can cause adverse tissue reactions resulting in osteolysis and ultimately in loosening of the fixation of the implant. When designing a simulator for evaluation of prospective materials for artificial hip joints it is important to verify that the type of relative motion at the articulation is similar to that produced in walking, involving continually changing direction of sliding. This paper is an overview of recent research done at Helsinki University of Technology on the analysis of the relationship between relative motion and wear in the prosthetic hip joint.To analyze the relative motion, software for computing tracks, referred to as slide tracks, drawn on the counterface by marker points on the bearing surface was developed and experimentally verified. The overall relative motion of the joint was illustrated by a slide track pattern, produced by many points. The patterns resulting from walking motion and from motion produced in ten contemporary hip simulator types were compared. The slide track computations were not limited to illustrational purposes but offered a basis for computing variations of sliding distances, sliding speeds and direction of sliding during a cycle. This was done for the slide track termed the force track, drawn by the resultant contact force. In addition, the product of the instantaneous load and increment of sliding distance was numerically integrated over a cycle. This track integral of load had so far not been determined for the majority of contemporary hip simulators. The track integral can be used in determining the wear factor, making it possible to compare clinical wear rates with those produced by hip simulators. The computation of the wear factor was subsequently improved by replacing the track integral of the resultant contact force with a surface integral computed as the sum of track integrals of a large number of smaller normal forces obtained by discretizing the contact pressure distribution. The slide track software could also be utilized in the conceptual design of new simulators because it was possible to rapidly investigate the effect of changes to the motion waveform amplitudes or phases, or of omitting certain waveforms to simplify the design of a simulator.The slide track analysis showed that walking motion produced mainly open tracks on the center of contact, implying continually changing direction of sliding. This phenomenon, which is crucial for obtaining the correct wear mechanisms for acetabular cups made of polyethylene, was reproduced by simulators having abduction-adduction motion in addition to flexion-extension motion. In the force track computations involving contemporary simulators with the common femoral head size of 28 mm, the sliding distance per cycle and the force track integral per cycle ranged from 19.7 to 34.3 mm and from 17.4 to 43.5 N m, respectively. The average sliding speed ranged from 19.7 to 49.0 mm/s. The sum of track integrals computed with forces obtained by discretizing the contact pressure distribution reached a substantially higher value than the track integral obtained with the resultant contact force only. This suggests that the wear factor is actually overestimated when computed in the conventional way by dividing the wear rate with the force track integral.

scholarly journals Study of Sensor Deflection in Hip Simulator : Numerical and Experimental Method

2018 ◽  
Vol 73 ◽  
pp. 01022
Author(s):  
Fabian Singgih Wicaksono ◽  
T Towijaya ◽  
Eko Saputra ◽  
Rifky Ismail ◽  
Mohammad Tauviqirrahman ◽  
...  
Keyword(s):  
Femoral Head ◽  
Hip Joint ◽  
Estimation Error ◽  
Wear Volume ◽  
Acetabular Cup ◽  
Hip Simulator ◽  
Artificial Hip ◽  
Process Simulator ◽  
Dial Indicator ◽  
Hip Joint Simulator

A lot of Hip Joint Simulator have been made nowadays, most of them use different structure and method. This research reports a pin-on-ring tribometer design that is used to became hip joint simulator based on the movement of the salat (salat gait). Modified femoral head and acetabular cup holder are performed, to design a reciprocating motion for simulation of artificial hip movement. An interesting finding from this study is a new linked-bar mechanism that leads to the ability to move femoral head against the acetabular cup and measure wear volume of an THR patients during normal salat gait. The designed motion angle is 121.5° in the flexion direction and 15.5° in the direction of abduction. Linked bar for sensor dial indicator have enough adjustment, but there is still a movement that is not rigid upon running hip joint process simulator. This research concentrates on the bar is already linked in accordance or not when compared with the data in the simulate on a computer. Estimation error and deviations that occur between numerical and experimental is going forward to improve hip joint simulator Undip to be more precise and relevant research to use THR Undip.

scholarly journals Comparison of Biocompatible Coatings Produced by Plasma Electrolytic Oxidation on cp-Ti and Ti-Zr-Nb Superelastic Alloy

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 401
Author(s):  
Ruzil Farrakhov ◽  
Olga Melnichuk ◽  
Evgeny Parfenov ◽  
Veta Mukaeva ◽  
Arseniy Raab ◽  
...  
Keyword(s):  
Plasma Electrolytic Oxidation ◽  
Electrochemical Impedance ◽  
Pure Titanium ◽  
Commercially Pure Titanium ◽  
X Ray ◽  
Kinetic Coefficients ◽  
Electrolytic Oxidation ◽  
Plasma Electrolytic ◽  
Cp Ti ◽  
Peo Coatings

The paper compares the coatings produced by plasma electrolytic oxidation (PEO) on commercially pure titanium and a novel superelastic alloy Ti-18Zr-15Nb (at. %) for implant applications. The PEO coatings were produced on both alloys in the identical pulsed bipolar regime. The properties of the coatings were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDX), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). The PEO process kinetics was modeled based on the Avrami theorem and Cottrell equation using a relaxation method. The resultant coatings contain TiO2, for both alloys, and NbO2, Nb2O5, ZrO2 for Ti-18Zr-15Nb alloy. The coating on the Ti-18Zr-15Nb alloy has a higher thickness, porosity, and roughness compared to that on cp-Ti. The values of the kinetic coefficients of the PEO process—higher diffusion coefficient and lower time constant for the processing of Ti-18Zr-15Nb—explain this effect. According to the electrochemical studies, PEO coatings on Ti-18Zr-15Nb alloy provide better corrosion protection. Higher corrosion resistance, porosity, and roughness contribute to better biocompatibility of the PEO coating on Ti-18Zr-15Nb alloy compared to cp-Ti.

Thermomechanical Response of Commercially Pure Titanium under Large Plastic Deformation at High Strain Rates

2012 ◽  
Vol 548 ◽  
pp. 174-178 ◽  
Author(s):  
Chong Yang Gao ◽  
Wei Ran Lu
Keyword(s):  
Pure Titanium ◽  
Optimal Solution ◽  
Optimization Method ◽  
Strain Rates ◽  
Commercially Pure Titanium ◽  
Thermomechanical Response ◽  
Commercially Pure ◽  
Different Temperatures ◽  
Cp Ti ◽  
Constitutive Parameters

By using a dislocation-based plastic constitutive model for hcp metals developed by us recently, the dynamic thermomechanical response of an important industrial material, commercially pure titanium (CP-Ti), was described at different temperatures and strain rates. The constitutive parameters of the material are determined by an efficient optimization method for a globally optimal solution. The model can well predict the dynamic response of CP-Ti by the comparison with experimental data and the Nemat-Nasser-Guo model.

Robotic-Arm Assisted Total Hip Arthroplasty Results in Smaller Acetabular Cup Size in Relation to the Femoral Head Size: A Matched-Pair Controlled Study

2017 ◽  
Vol 27 (2) ◽  
pp. 147-152 ◽  
Author(s):  
Carlos Suarez-Ahedo ◽  
Chengcheng Gui ◽  
Timothy J. Martin ◽  
Sivashankar Chandrasekaran ◽  
Parth Lodhia ◽  
...  
Keyword(s):  
Femoral Head ◽  
Head Size ◽  
Robotic Arm ◽  
Matched Pair ◽  
Femoral Head Size ◽  
Acetabular Cup ◽  
Acetabular Bone ◽  
Head Diameter ◽  
Total Hip ◽  
Femoral Head Diameter

Purpose To compare the acetabular component size relative to the patient's native femoral head size between conventional THA (CTHA) approach and robotic-arm assisted THA (RTHA) to infer which of these techniques preserved more acetabular bone. Methods Patients were included if they had primary osteoarthritis (OA) and underwent total hip replacement between June 2008 and March 2014. Patients were excluded if they had missing or rotated postoperative anteroposterior radiographs. RTHA patients were matched to a control group of CTHA patients, in terms of preoperative native femoral head size, age, gender, body mass index (BMI) and approach. Acetabular cup size relative to femoral head size was used as a surrogate for amount of bone resected. We compared the groups according to 2 measures describing acetabular cup diameter ( c) in relation to femoral head diameter ( f): (i) c-f, the difference between cup diameter and femoral head diameter and (ii) ( c-f)/ f, the same difference as a fraction of femoral head diameter. Results 57 matched pairs were included in each group. There were no significant differences between groups for demographic measures, femoral head diameter, or acetabular cup diameter (p>0.05). However, measures (i) and (ii) did differ significantly between the groups, with lower values in the RTHA group (p<0.02). Conclusions Using acetabular cup size relative to femoral head size as an approximate surrogate measure of acetabular bone resection may suggest greater preservation of bone stock using RTHA compared to CTHA. Further studies are needed to validate the relationship between acetabular cup size and bone loss in THA.

Application of MCDM-based TOPSIS method for the selection of optimal process parameter in turning of pure titanium

2017 ◽  
Vol 24 (7) ◽  
pp. 2009-2021 ◽  
Author(s):  
Akhtar Khan ◽  
Kalipada Maity
Keyword(s):  
Decision Making ◽  
Cutting Force ◽  
Pure Titanium ◽  
Cutting Speed ◽  
Optimal Combination ◽  
Depth Of Cut ◽  
Topsis Method ◽  
Content Type ◽  
Cp Ti ◽  
Selection Of

Purpose The purpose of this paper is to explore a multi-criteria decision-making (MCDM) methodology to determine an optimal combination of process parameters that is capable of generating favorable dimensional accuracy and product quality during turning of commercially pure titanium (CP-Ti) grade 2. Design/methodology/approach The present paper recommends an optimal combination of cutting parameters with an aim to minimize the cutting force (Fc), surface roughness (Ra), machining temperature (Tm) and to maximize the material removal rate (MRR) after turning of CP-Ti grade 2. This was achieved by the simultaneous optimization of the aforesaid output characteristics (i.e. Fc, Ra, Tm, and MRR) using the MCDM-based TOPSIS method. Taguchi’s L9 orthogonal array was used for conducting the experiments. The output responses (cutting force: Fc, surface roughness: Ra, machining temperature: Tm and MRR) were integrated together and presented in terms of a single signal-to-noise ratio using the Taguchi method. Findings The results of the proposed methodology depict that the higher MRR with desirable surface quality and the lower cutting force and machining temperature were observed at a combination of cutting variables as follows: cutting speed of 105 m/min, feed rate of 0.12 mm/rev and depth of cut of 0.5 mm. The analysis of variance test was conducted to evaluate the significance level of process parameters. It is evident from the aforesaid test that the depth of cut was the most significant process parameter followed by cutting speed. Originality/value The selection of an optimal parametric combination during the machining operation is becoming more challenging as the decision maker has to consider a set of distinct quality characteristics simultaneously. This situation necessitates an efficient decision-making technique to be used during the machining operation. From the past literature, it is noticed that only a few works were reported on the multi-objective optimization of turning parameters using the TOPSIS method so far. Thus, the proposed methodology can help the decision maker and researchers to optimize the multi-objective turning problems effectively in combination with a desirable accuracy.

The Influence of Laser Irradiation Parameters on Tribological Behaviour of Commercially Pure Titanium for Dental Prostheses

2016 ◽  
Author(s):  
Karibeeran Shanmuga Sundaram ◽  
Gurusami Kiliyappan ◽  
Senthil Kumaran Selvadurai
Keyword(s):  
Surface Roughness ◽  
Wear Resistance ◽  
Pure Titanium ◽  
Laser Surface ◽  
Commercially Pure Titanium ◽  
Laser Shock ◽  
Micro Hardness ◽  
Dental Prostheses ◽  
Commercially Pure ◽  
Cp Ti

Laser shock peening (LSP) is one of the innovative technique that produces a compressive residual stress on the surface of metallic materials, thereby significantly increasing its fatigue life in applications where failure is caused by surface-initiated cracks. The specimens were treated with laser shock waves with different processing parameters, and characterization studies were made on treated specimens. The purpose of the present study was to investigate the influence of Nd:YAG laser on commercially pure titanium (CP-Ti) used in prosthetic dental restorations. The treatment influenced change in microstructure, micro hardness, surface roughness, and wear resistance characteristics. Though CP-Ti is considered as an excellent material for dental applications due to its outstanding biocompatibility, it is not suitable when high mastication forces are applied. In the present study, pulsed Nd:YAG laser surface treatment technique was adopted to improve the wear resistance of CP-Ti. The wear test pin specimens of CP-Ti were investment cast with centrifugal titanium casting machine. The wear properties of specimens were evaluated after LSP on a “pin-on-disc” wear testing tribometer, as per ASTM G99-05 standards. The results of the wear experiment showed that the treated laser surface has higher wear resistance, micro hardness, and surface roughness compared to as-cast samples. The improvement of wear resistance may be attributed due to grain refinement imparted by LSP processes. The microstructure, wear surfaces, wear debris, and morphology of the specimen were analyzed by using optical electron microscope, scanning electron microscope, and X-ray diffraction (XRD). The data were compared using ANOVA and post-hoc Tukey tests. The characteristic change resulted in increase in wear resistance and decrease in wear rate. Hence, it is evident that the more reliable and removable partial denture metal frameworks for dental prostheses may find its applications.

scholarly journals The influence of mold temperature on the fit of cast crowns with commercially pure titanium

2005 ◽  
Vol 19 (2) ◽  
pp. 139-143 ◽  
Author(s):  
Wagner Sotero Fragoso ◽  
Guilherme Elias Pessanha Henriques ◽  
Edwin Fernando Ruiz Contreras ◽  
Marcelo Ferraz Mesquita
Keyword(s):  
Pure Titanium ◽  
Mold Temperature ◽  
Commercially Pure Titanium ◽  
Mechanical Grinding ◽  
Marginal Fit ◽  
Commercially Pure ◽  
Cp Ti

Commercially pure titanium (CP Ti) has been widely applied to fabricate cast devices because of its favorable properties. However, the mold temperature recommended for the manufacture of casts has been considered relatively low, causing inadequate castability and poor marginal fit of cast crowns. This study evaluated and compared the influence of mold temperature (430°C - as control, 550°C, 670°C) on the marginal discrepancies of cast CP Ti crowns. Eight bovine teeth were prepared on a mechanical grinding device and impressions were used to duplicate each tooth and produce eight master dies. Twenty-four crowns were fabricated using CP Ti in three different groups of mold temperature (n = 8): 430°C (as control), 550°C and 670°C. The gap between the crown and the bovine tooth was measured at 50 X magnification with a traveling microscope. The marginal fit values of the cast CP Ti crowns were submitted to the Kruskal-Wallis test (p = 0.03). The 550°C group (95.0 µm) showed significantly better marginal fit than the crowns of the 430°C group (203.4 µm) and 670°C group (213.8 µm). Better marginal fit for cast CP Ti crowns was observed with the mold temperature of 550°C, differing from the 430°C recommended by the manufacturer.

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