Osteoporotic Bone Augmentation Utilizing Curved Pattern of PMMA Injection: A Combined Finite Element and Optimization Investigation

2019 ◽  
Author(s):  
Amirhossein Farvardin ◽  
Mehran Armand
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Hip Fractures ◽  
Experimental Validation ◽  
Preoperative Planning ◽  
Osteoporotic Bone ◽  
Bone Augmentation ◽  
Hydrodynamic Simulations ◽  
Yield Load ◽  
Straight Line

Abstract A potential effective treatment for prevention of osteoporotic hip fractures is augmentation of the mechanical properties of the femur by injecting it with Polymethyl-Methacrylate (PMMA). We have previously developed a preoperative planning workstation to optimize the pattern of cement injection. In this planning paradigm, injections occur on a straight line limiting the overall match between the optimal and injected volumes of the cement. In addition, new advancements in drilling techniques has made it possible to plan and drill the bone based on a curved trajectory. In this study, we introduced a methodology to find the optimal drill path for PMMA injection. With the aid of Finite Element (FE) and hydrodynamic simulations, the effectiveness of the proposed approach was evaluated. Results showed that with an average injection of 7.2 ml, the proposed method can increase the yield load of the femur by 69%. Future works involve experimental validation of this method in cadaveric studies.

Cement Placement Optimization in Femoral Augmentation Using an Evolutionary Algorithm

2013 ◽  
Author(s):  
Ehsan Basafa ◽  
Mehran Armand
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Stress Distribution ◽  
Structural Optimization ◽  
Initial Conditions ◽  
Uniform Stress ◽  
Yield Load ◽  
Load Models ◽  
Placement Optimization ◽  
Evolutionary Structural Optimization

We used the method of Bi-directional Evolutionary Structural Optimization (BESO) to optimize the cement placement in finite element (FE) models of osteoporotic femur specimens. Two different initial conditions, i.e. no initial cement and fully cemented, were used and both converged to the same optimal cement pattern. On average, BESO predicted that, if optimized, augmentation with only 18.6ml of cement will result in 100% increase in the yield load of the models. Simulations also showed a linear relationship between the volume of the cement and the models’ stiffness and yield load. Models initially filled with cement had a much more uniform stress distribution among the cemented elements when optimized, compared to the starting configuration. Results suggest that restoring the mechanical properties of osteoporotic femurs is possible with minimal and, therefore, potentially safe volumes of cement.

scholarly journals Force and Torque Modeling for the Drilling of Bone for use in Orthopaedic Haptic Simulation Systems

2021 ◽  
Author(s):  
Troy MacAvelia
Keyword(s):  
Finite Element ◽  
Orthopaedic Surgery ◽  
Experimental Validation ◽  
Prediction Models ◽  
Preoperative Planning ◽  
Validation Process ◽  
Femur Bone ◽  
Element Simulation ◽  
Haptic Simulation ◽  
Simulation Systems

The advent of haptic simulation systems for orthopaedic surgery procedures has provided surgeons with a tool for training and preoperative planning. This is especially true for procedures involving the drilling of bone which requires a great amount of adroitness and experience. One of the potential difficulties with the drilling of bone is the lack of consistent material evacuation from the drill’s flutes as the material tends to clog. This clogging leads to significant increases in force and torque experienced by the surgeon which has not been appropriately addressed by current simulation systems. This thesis proposes several force and torque prediction models that account for this phenomenon. Each of the models was calibrated via experimentation and their accuracy was substantiated through an experimental validation process. As an example of the application of the models, a finite element simulation investigating the effect of drilling forces and moments on the dynamic response of a femur bone was studied.

scholarly journals Force and Torque Modeling for the Drilling of Bone for use in Orthopaedic Haptic Simulation Systems

2021 ◽  
Author(s):  
Troy MacAvelia
Keyword(s):  
Finite Element ◽  
Orthopaedic Surgery ◽  
Experimental Validation ◽  
Prediction Models ◽  
Preoperative Planning ◽  
Validation Process ◽  
Femur Bone ◽  
Element Simulation ◽  
Haptic Simulation ◽  
Simulation Systems

The advent of haptic simulation systems for orthopaedic surgery procedures has provided surgeons with a tool for training and preoperative planning. This is especially true for procedures involving the drilling of bone which requires a great amount of adroitness and experience. One of the potential difficulties with the drilling of bone is the lack of consistent material evacuation from the drill’s flutes as the material tends to clog. This clogging leads to significant increases in force and torque experienced by the surgeon which has not been appropriately addressed by current simulation systems. This thesis proposes several force and torque prediction models that account for this phenomenon. Each of the models was calibrated via experimentation and their accuracy was substantiated through an experimental validation process. As an example of the application of the models, a finite element simulation investigating the effect of drilling forces and moments on the dynamic response of a femur bone was studied.

scholarly journals Symmetric Nature of Stress Distribution in the Elastic-Plastic Range of Pinus L. Pine Wood Samples Determined Experimentally and Using the Finite Element Method (FEM)

Symmetry ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 39
Author(s):  
Łukasz Warguła ◽  
Dominik Wojtkowiak ◽  
Mateusz Kukla ◽  
Krzysztof Talaśka
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Stress Distribution ◽  
Moisture Content ◽  
Tool Geometry ◽  
Wood Fibers ◽  
Data Set ◽  
Plastic Deformations ◽  
Pine Wood ◽  
Elastic Plastic

This article presents the results of experimental research on the mechanical properties of pine wood (Pinus L. Sp. Pl. 1000. 1753). In the course of the research process, stress-strain curves were determined for cases of tensile, compression and shear of standardized shapes samples. The collected data set was used to determine several material constants such as: modulus of elasticity, shear modulus or yield point. The aim of the research was to determine the material properties necessary to develop the model used in the finite element analysis (FEM), which demonstrates the symmetrical nature of the stress distribution in the sample. This model will be used to analyze the process of grinding wood base materials in terms of the peak cutting force estimation and the tool geometry influence determination. The main purpose of the developed model will be to determine the maximum stress value necessary to estimate the destructive force for the tested wood sample. The tests were carried out for timber of around 8.74% and 19.9% moisture content (MC). Significant differences were found between the mechanical properties of wood depending on moisture content and the direction of the applied force depending on the arrangement of wood fibers. Unlike other studies in the literature, this one relates to all three stress states (tensile, compression and shear) in all significant directions (anatomical). To verify the usability of the determined mechanical parameters of wood, all three strength tests (tensile, compression and shear) were mapped in the FEM analysis. The accuracy of the model in determining the maximum destructive force of the material is equal to the average 8% (for tensile testing 14%, compression 2.5%, shear 6.5%), while the average coverage of the FEM characteristic with the results of the strength test in the field of elastic-plastic deformations with the adopted ±15% error overlap on average by about 77%. The analyses were performed in the ABAQUS/Standard 2020 program in the field of elastic-plastic deformations. Research with the use of numerical models after extension with a damage model will enable the design of energy-saving and durable grinding machines.

Cold expansion of rail-end-bolt holes: finite element predictions and experimental validation by DIC and strain gauges

2021 ◽  
pp. 106275
Author(s):  
Giovanni Pio Pucillo ◽  
Alessandro Carrabs ◽  
Stefano Cuomo ◽  
Adam Elliott ◽  
Michele Meo
Keyword(s):  
Finite Element ◽  
Experimental Validation ◽  
Strain Gauges ◽  
Cold Expansion ◽  
Bolt Holes

scholarly journals Characterization of Mechanical Heterogeneity in Dissimilar Metal Welded Joints

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4145
Author(s):  
He Xue ◽  
Zheng Wang ◽  
Shuai Wang ◽  
Jinxuan He ◽  
Hongliang Yang
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Welded Joints ◽  
Structural Integrity ◽  
Material Interfaces ◽  
Mechanical Heterogeneity ◽  
Finite Element Software ◽  
Dissimilar Metal ◽  
Stress Changes

Dissimilar metal welded joints (DMWJs) possess significant localized mechanical heterogeneity. Using finite element software ABAQUS with the User-defined Material (UMAT) subroutine, this study proposed a constitutive equation that may be used to express the heterogeneous mechanical properties of the heat-affected and fusion zones at the interfaces in DMWJs. By eliminating sudden stress changes at the material interfaces, the proposed approach provides a more realistic and accurate characterization of the mechanical heterogeneity in the local regions of DMWJs than existing methods. As such, the proposed approach enables the structural integrity of DMWJs to be analyzed in greater detail.

Finite Element Analysis of Reinforced Concrete Beams with Exterior FRP Shell

2011 ◽  
Vol 243-249 ◽  
pp. 1461-1465
Author(s):  
Chuan Min Zhang ◽  
Chao He Chen ◽  
Ye Fan Chen
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Test Results ◽  
Contact Interface ◽  
Accurate Calculation ◽  
Element Analysis

The paper makes an analysis of the reinforced concrete beams with exterior FRP Shell in Finite Element, and compares it with the test results. The results show that, by means of this model, mechanical properties of reinforced concrete beams with exterior FRP shell can be predicted better. However, the larger the load, the larger deviation between calculated values and test values. Hence, if more accurate calculation is required, issues of contact interface between the reinforced concrete beams and the FRP shell should be taken into consideration.

scholarly journals Applicability of a Three-Layer Model for the Dynamic Analysis of Ballasted Railway Tracks

Vibration ◽  
2021 ◽  
Vol 4 (1) ◽  
pp. 151-174
Author(s):  
André F. S. Rodrigues ◽  
Zuzana Dimitrovová
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Dynamic Analysis ◽  
Shear Stiffness ◽  
Shear Resistance ◽  
Railway Track ◽  
Fe Model ◽  
Inertial Effects ◽  
Layer Model ◽  
3D Finite Element

In this paper, the three-layer model of ballasted railway track with discrete supports is analyzed to access its applicability. The model is referred as the discrete support model and abbreviated by DSM. For calibration, a 3D finite element (FE) model is created and validated by experiments. Formulas available in the literature are analyzed and new formulas for identifying parameters of the DSM are derived and validated over the range of typical track properties. These formulas are determined by fitting the results of the DSM to the 3D FE model using metaheuristic optimization. In addition, the range of applicability of the DSM is established. The new formulas are presented as a simple computational engineering tool, allowing one to calculate all the data needed for the DSM by adopting the geometrical and basic mechanical properties of the track. It is demonstrated that the currently available formulas have to be adapted to include inertial effects of the dynamically activated part of the foundation and that the contribution of the shear stiffness, being determined by ballast and foundation properties, is essential. Based on this conclusion, all similar models that neglect the shear resistance of the model and inertial properties of the foundation are unable to reproduce the deflection shape of the rail in a general way.

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