scholarly journals Effect of Plate Type and Working Length on a Synthetic Compressed Juxta-Articular Fracture Model

VCOT Open ◽  
2020 ◽  
Vol 03 (02) ◽  
pp. e119-e128
Author(s):  
Guy Bird ◽  
Mark Glyde ◽  
Giselle Hosgood ◽  
Alex Hayes ◽  
Rob Day
Keyword(s):  
Three Dimensional ◽  
Biomechanical Properties ◽  
Regions Of Interest ◽  
Surface Strain ◽  
Image Correlation ◽  
Fracture Model ◽  
Short Fragment ◽  
Working Length ◽  
Multiple Regions ◽  
Short Working

Abstract Objective This investigation compared the biomechanical properties of a 2.0 mm locking compression notched head T-plate (NHTP) and 2.0 mm straight locking compression plate (LCP), in a compressed, short, juxta-articular fragment fracture model. Methods Two different screw configurations were compared for the NHTP and LCP, modelling short (configuration 1) and long working length (configuration 2). Constructs were tested in compression, perpendicular and tension four-point bending and torsion. Plate surface strain was measured at 12 regions of interest using three-dimensional digital image correlation. Stiffness and strain were compared. Results The LCP was stiffer than the NHTP in all three planes of bending (p < 0.05). The NHTP was stiffer than the LCP in torsion (p < 0.05). The NHTP had greater strain than the LCP during compression bending and torsion (p < 0.0005). The short working length NHTP was stiffer in all three planes of bending and in torsion (p < 0.05) than the longer working length. The short working length LCP was stiffer in compression bending and in torsion (p < 0.05) than the longer working length. The long working length showed greater strain than the short working length at multiple regions of interest. Conclusion In this experimental model of a compressed transverse fracture with a juxta-articular 9 mm fragment, a 2.0 mm LCP with two hybrid screws in the short fragment was stiffer than a 2.0 mm NHTP with three locking screws in the short fragment in three planes of bending but not torsion. Extending the working length of each construct reduced construct stiffness and increased plate strain.

scholarly journals Biomechanical Comparison of a Notched Head Locking T-Plate and a Straight Locking Compression Plate in a Juxta-Articular Fracture Model

2020 ◽  
Author(s):  
Guy Bird ◽  
Mark Glyde ◽  
Giselle Hosgood ◽  
Alex Hayes ◽  
Robert Day
Keyword(s):  
Three Dimensional ◽  
Locking Compression Plate ◽  
Surface Strain ◽  
Image Correlation ◽  
Fracture Model ◽  
Articular Fracture ◽  
Short Fragment ◽  
Working Length ◽  
Compression Plate ◽  
Short Working

Abstract Objective This investigation compared the biomechanical properties of a 2.0 mm locking compression notched head T-plate (NHTP) and 2.0 mm straight locking compression plate (LCP), in a simple transverse juxta-articular fracture model. Study Design Two different screw configurations were compared for the NHTP and LCP, modelling short (configuration 1) and long working length (configuration 2). Constructs were tested in compression, perpendicular and tension non-destructive four point bending and torsion. Plate surface strain was measured at 12 regions of interest (ROI) using three-dimensional digital image correlation. Stiffness and strain were compared between screw configurations within and between each plate. Results The LCP was stiffer than the NHTP in all three planes of bending and torsion (p < 0.05). The NHTP had greater strain than the LCP during compression bending and torsion at all ROI (p < 0.0005). The short working length was stiffer in all three planes of bending and in torsion (p < 0.05) than the longer working length for both plates. The long working length showed greater strain than the short working length at most ROI. Conclusion In this experimental model, a 2.0 mm LCP with two screws in the short fragment was significantly stiffer and had lower plate strain than a 2.0 mm NHTP with three screws in the short fragment. Extending the working length significantly reduced construct stiffness and increased plate strain. These findings may guide construct selection.

The effect of intramedullary pin size and plate working length on plate strain in locking compression plate-rod constructs under axial load

2016 ◽  
Vol 29 (06) ◽  
pp. 451-458 ◽  
Author(s):  
Mark Glyde ◽  
Robert Day ◽  
Giselle Hosgood ◽  
Tim Pearson
Keyword(s):  
Large Diameter ◽  
Three Dimensional ◽  
Fracture Site ◽  
Locking Compression Plate ◽  
Image Correlation ◽  
Lower Strain ◽  
Working Length ◽  
Significant Difference ◽  
Compression Plate ◽  
Short Working

SummaryObjective: To investigate the effect of intramedullary pin size and plate working length on plate strain in locking compression plate-rod constructs.Methods: A synthetic bone model with a 40 mm fracture gap was used. Locking compression plates with monocortical locking screws were tested with no pin (LCP-Mono) and intramedullary pins of 20% (LCPR-20), 30% (LCPR-30) and 40% (LCPR-40) of intramedullary diameter. Two screws per fragment modelled a long (8-hole) and short (4-hole) plate working length. Strain responses to axial compression were recorded at six regions of the plate via three-dimensional digital image correlation.Results: The addition of a pin of any size provided a significant decrease in plate strain. For the long working length, LCPR-30 and LCPR-40 had significantly lower strain than the LCPR-20, and plate strain was significantly higher adjacent to the screw closest to the fracture site. For the short working length, there was no significant difference in strain across any LCPR constructs or at any region of the plate. Plate strain was significantly lower for the short working length compared to the long working length for the LCP-Mono and LCPR-20 constructs, but not for the LCPR-30 and LCPR-40 constructs.Clinical significance: The increase in plate strain encountered with a long working length can be overcome by the use of a pin of 30–40% intramedullary diameter. Where placement of a large diameter pin is not possible, screws should be placed as close to the fracture gap as possible to minimize plate strain and distribute it more evenly over the plate.

Flexural Behavior of a Layer-to-Layer Orthogonal Interlocked Three-Dimensional Textile Composite

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
D. Zhang ◽  
A. M. Waas ◽  
M. Pankow ◽  
C. F. Yen ◽  
S. Ghiorse
Keyword(s):  
Mechanical Response ◽  
Peak Load ◽  
Three Dimensional ◽  
Peak Stress ◽  
Surface Strain ◽  
Image Correlation ◽  
Flexural Behavior ◽  
Fe Model ◽  
Textile Composite ◽  
The Matrix

The flexural response of a three-dimensional (3D) layer-to-layer orthogonal interlocked textile composite has been investigated under quasi-static three-point bending. Fiber tow kinking on the compressive side of the flexed specimens has been found to be a strength limiting mechanism for both warp and weft panels. The digital image correlation (DIC) technique has been utilized to map the deformation and identify the matrix microcracking on the tensile side prior to the peak load in the warp direction loaded panels. It has been shown that the geometrical characteristics of textile reinforcement play a key role in the mechanical response of this class of material. A 3D local–global finite element (FE) model that reflects the textile architectures has been proposed to successfully capture the surface strain localizations in the predamage region. To analyze the kink banding event, the fiber tow is modeled as an inelastic degrading homogenized orthotropic solid in a state of plane stress based on Schapery Theory (ST). The predicted peak stress is in agreement with the tow kinking stress obtained from the 3D FE model.

scholarly journals A method for predicting the blasting pressure of balloons using the surface strain in low pressure

2019 ◽  
Vol 11 (10) ◽  
pp. 168781401988155
Author(s):  
Yong-Zheng Shen ◽  
Guo-Chang Lin ◽  
Hui-Feng Tan
Keyword(s):  
Internal Pressure ◽  
Correction Factor ◽  
Three Dimensional ◽  
Reference Value ◽  
Surface Strain ◽  
Test Strain ◽  
Image Correlation ◽  
Correlation Technique ◽  
Maximum Test ◽  
Novel Method

Balloons made by cut fabric pieces are widely used in space research. To predict the blasting pressure of a balloon, we propose a novel method based on the non-contact test strain at a low internal pressure. The three-dimensional digital image correlation technique is introduced to measure the surface strain of the balloon. Representative regions of the balloon are selected as the test regions. A correction factor is proposed that accounts for the relationship between the internal pressure and the surface strain for the actual and the ideal balloon. By combining the maximum surface strain at a given internal pressure and the correction factor, we can predict the blasting pressure of the balloon. A blasting test is carried out to verify the feasibility of the predictive method. When the value of the ratio of the maximum test strain to the limiting strain reaches about a reference value, the absolute value of the deviation percentage between the predicted blasting pressure and the actual blasting pressure is less than 10%. The blasting pressure for balloon can be predicted accurately. This method does not require the balloon to be inflated to a high internal pressure, which improves the practicality of the prediction.

Temporal Development of Material Properties in Free Swelling Chondrocyte-Seeded Agarose Constructs

2001 ◽  
Author(s):  
Terri-Ann N. Kelly ◽  
Christopher C.-B. Wang ◽  
Nadeen O. Chahine ◽  
Gerard A. Ateshian ◽  
Clark T. Hung
Keyword(s):  
Material Properties ◽  
Biochemical Analysis ◽  
Three Dimensional ◽  
Biomechanical Properties ◽  
Image Correlation ◽  
Cartilage Explants ◽  
Polymer Systems ◽  
Free Swelling ◽  
Hydrogel Polymer

Abstract An understanding of chondrocyte mechanotransduction requires knowledge of the deformational fields within the tissue. Since the study of chondrocyte mechanotransduction in articular cartilage explants is hampered by its inhomogeneous biochemical composition and biomechanical properties, investigators have performed loading studies of chondrocyte-suspended hydrogel polymer systems such as agarose [1]. Prior to significant matrix elaboration by the cells, the agarose offers a uniform, uncharged three-dimensional (3D) mechanical environment for chondrocytes [2,3]. In this study, a technique, which combines video microscopy [4] and digital image correlation [5], was used to provide a novel characterization of the temporal changes in displacement field, apparent Young’s Modulus and apparent Poisson’s ratio of free swelling chondrocyte-seeded agarose constructs. Biochemical analysis was performed to permit correlation of these parameters with matrix elaboration.

Nonlinear Membrane Direct and Inverse FEM Analysis

2014 ◽  
Author(s):  
Mattia Alioli ◽  
Pierangelo Masarati ◽  
Marco Morandini ◽  
Trenton Carpenter ◽  
Roberto Albertani
Keyword(s):  
Three Dimensional ◽  
Fem Analysis ◽  
Solution Procedure ◽  
General Purpose ◽  
Inverse Solution ◽  
Surface Strain ◽  
Image Correlation ◽  
Direct Solution ◽  
Strain Measurements ◽  
Solution Approach

The analysis of thin structural components integrated within a general-purpose multibody system dynamics formulation is presented. An original inverse finite element solution procedure is developed to reconstruct the deformed shape of a membrane from in-plane membrane strain measurements, and eventually indirectly estimate the distributed loads. A direct solution approach is used in co-simulation with fluid-dynamics solvers to predict the configuration of the system under static and unsteady loads. Numerical validation of the inverse solution is performed considering the results of direct solution analysis. The direct and inverse solutions are validated considering experimental displacement and strain measurements obtained using digital image correlation. Moving Least Squares are used to smooth and remap measurements as needed by the inverse solution meshing. Utilizing surface strain measurements from strain sensors, the methodology enables the accurate computation of the three-dimensional displacement field.

Deformation Measurements and Material Property Estimation of Mouse Carotid Artery Using a Microstructure-Based Constitutive Model

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Jinfeng Ning ◽  
Shaowen Xu ◽  
Ying Wang ◽  
Susan M. Lessner ◽  
Michael A. Sutton ◽  
...  
Keyword(s):  
Carotid Artery ◽  
Constitutive Model ◽  
Vascular Tissue ◽  
Three Dimensional ◽  
Tensile Loading ◽  
Surface Strain ◽  
Image Correlation ◽  
Element Analysis ◽  
Constitutive Parameters ◽  
Deformation Measurements

A series of pressurization and tensile loading experiments on mouse carotid arteries is performed with deformation measurements acquired during each experiment using three-dimensional digital image correlation. Using a combination of finite element analysis and a microstructure-based constitutive model to describe the response of biological tissue, the measured surface strains during pressurization, and the average axial strains during tensile loading, an inverse procedure is used to identify the optimal constitutive parameters for the mouse carotid artery. The results demonstrate that surface strain measurements can be combined with computational methods to identify material properties in a vascular tissue. Additional computational studies using the optimal material parameters for the mouse carotid artery are discussed with emphasis on the significance of the qualitative trends observed.

Anisotropic Ductile Fracture of AA6260-T6 Al-Alloy Extrusions

2011 ◽  
Author(s):  
M. Luo ◽  
T. Wierzbicki ◽  
D. Mohr
Keyword(s):  
Ductile Fracture ◽  
Weighting Function ◽  
Extrusion Direction ◽  
Material Point ◽  
Surface Strain ◽  
Image Correlation ◽  
Fracture Model ◽  
Model Parameters ◽  
Al Alloy ◽  
Wide Range

The anisotropic ductile fracture of AA6260-T6 extruded aluminum alloy profiles is studied within a phenomenological framework. A basic fracture testing program covering a wide range of stress states and three distinct material orientations (i.e. 0°, 45° and 90° with respect to the extrusion direction) is carried out. It comprises notched tensile specimens, tensile specimens with a central hole, butterfly shear specimens and circular punch specimens. The surface strain fields are determined using Digital Image Correlation (DIC), while a finite element simulation is performed of each experiment to determine the local stress and strain histories at the material point where fracture initiates. The experimental-numerical analysis reveals a strong anisotropy of the present material ductility/fracture, which cannot be approximated by existing isotropic fracture models. A new non-associated anisotropic fracture model is proposed incorporating the stress state dependent Modified Mohr-Coulomb (MMC) weighting function and a material direction sensitive damage rule. All seven fracture model parameters are identified for the present extruded aluminum using an inverse method. The good agreement of the model predictions with the results from fourteen distinct experiments demonstrates the remarkable predictive capabilities of the proposed model.

scholarly journals In-Process Measurement of Three-Dimensional Deformations Based on Speckle Photography

2021 ◽  
Vol 11 (11) ◽  
pp. 4981
Author(s):  
Andreas Tausendfreund ◽  
Dirk Stöbener ◽  
Andreas Fischer
Keyword(s):  
Evaluation Method ◽  
Process Analysis ◽  
Plane Deformation ◽  
Three Dimensional ◽  
Machining Process ◽  
Image Correlation ◽  
Speckle Photography ◽  
Process Measurement ◽  
Out Of Plane ◽  
Plane Deformations

In the concept of the process signature, the relationship between a material load and the modification remaining in the workpiece is used to better understand and optimize manufacturing processes. The basic prerequisite for this is to be able to measure the loads occurring during the machining process in the form of mechanical deformations. Speckle photography is suitable for this in-process measurement task and is already used in a variety of ways for in-plane deformation measurements. The shortcoming of this fast and robust measurement technique based on image correlation techniques is that out-of-plane deformations in the direction of the measurement system cannot be detected and increases the measurement error of in-plane deformations. In this paper, we investigate a method that infers local out-of-plane motions of the workpiece surface from the decorrelation of speckle patterns and is thus able to reconstruct three-dimensional deformation fields. The implementation of the evaluation method enables a fast reconstruction of 3D deformation fields, so that the in-process capability remains given. First measurements in a deep rolling process show that dynamic deformations underneath the die can be captured and demonstrate the suitability of the speckle method for manufacturing process analysis.

scholarly journals Increase in Total Elongation Caused by Pure Shear Deformation in Ultra-Fine-Grained Cu Processed by Equal-Channel Angular Pressing

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 654
Author(s):  
Ryosuke Matsutani ◽  
Nobuo Nakada ◽  
Susumu Onaka
Keyword(s):  
Shear Deformation ◽  
Equal Channel Angular Pressing ◽  
Pure Shear ◽  
Three Dimensional ◽  
Tensile Tests ◽  
Total Elongation ◽  
Local Deformation ◽  
Image Correlation ◽  
Fine Grained ◽  
Angular Pressing

Ultra-fine-grained (UFG) Cu shows little total elongation in tensile tests because simple shear deformation is concentrated in narrow regions during the initial stage of plastic deformation. Here, we attempted to improve the total elongation of UFG Cu obtained by equal-channel angular pressing. By making shallow dents on the side surfaces of the plate-like specimens, this induced pure shear deformation and increased their total elongation. During the tensile tests, we observed the overall and local deformation of the dented and undented UFG Cu specimens. Using three-dimensional digital image correlation, we found that the dented specimens showed suppression of thickness reduction and delay in fracture by enhancement of pure shear deformation. However, the dented and undented specimens had the same ultimate tensile strength. These results provide us a new concept to increase total elongation of UFG materials.

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