scholarly journals Effect of Impact Velocity, Flooring Material, and Trochanteric Soft-Tissue Quality on Acetabular Fracture during a Sideways Fall: A Parametric Finite Element Approach

2021 ◽  
Vol 11 (1) ◽  
pp. 365
Author(s):  
Shahab Khakpour ◽  
Petri Tanska ◽  
Amir Esrafilian ◽  
Mika E. Mononen ◽  
Simo Saarakkala ◽  
...  
Keyword(s):  
Finite Element ◽  
Soft Tissue ◽  
Impact Velocity ◽  
Acetabular Fracture ◽  
Whole Body ◽  
Acetabular Fractures ◽  
Tissue Quality ◽  
The Impact ◽  
Flooring Materials ◽  
Flooring Material

A low-energy acetabular fracture, as a result of falling from standing height, is common among elderly patients and the number of cases is increasing rapidly in developed countries. Several biomechanical factors contribute to the incidence, severity, and type of acetabular fractures, such as body configuration at the impact moment or bone and soft-tissue quality. The current parametric study developed a comprehensive finite element model of the pelvic girdle and simple representation of the whole body and investigated the effects of impact velocity, conventional indoor/outdoor flooring material, and trochanteric soft-tissue stiffness on an acetabular fracture. Our results show that whereas the impact velocity has a substantial influence on the incidence and type of acetabular fracture, the effects of conventional flooring materials and trochanteric soft-tissue quality are not remarkable. It seems that other factors such as the quality of bone (healthy vs. osteoporotic), the thickness of trochanteric soft-tissue, and body configuration at the impact are more critical in the occurrence and type of the acetabular fracture. These results can be valuable in the prevention of acetabular fractures and the design of protective measures such as hip pads or novel flooring materials.

Quantifying Variability in Lumbar L4-L5 Soft Tissue Properties for Use in Finite-Element Analysis

2016 ◽  
Vol 1 (3) ◽  
Author(s):  
Dana J. Coombs ◽  
Paul J. Rullkoetter ◽  
Peter J. Laz
Keyword(s):  
Finite Element ◽  
Soft Tissue ◽  
Experimental Testing ◽  
Intersubject Variability ◽  
Probabilistic Representation ◽  
Posterior Portion ◽  
Annulus Fibrosis ◽  
Interspinous Ligament ◽  
Constitutive Material Model ◽  
The Impact

Soft tissue structures of the L4-L5 level of the human lumbar spine are represented in finite-element (FE) models, which are used to evaluate spine biomechanics and implant performance. These models typically use average properties; however, experimental testing reports variation up to 40% in ligament stiffness and even greater variability for annulus fibrosis (AF) properties. Probabilistic approaches enable consideration of the impact of intersubject variability on model outputs. However, there are challenges in directly applying the variability in measured load–displacement response of structures to a finite-element model. Accordingly, the objectives of this study were to perform a comprehensive review of the properties of the L4-L5 structures and to develop a probabilistic representation to characterize variability in the stiffness of spinal ligaments and parameters of a Holzapfel–Gasser–Ogden constitutive material model of the disk. The probabilistic representation was determined based on direct mechanical test data as found in the literature. Monte Carlo simulations were used to determine the uncertainty of the Holzapfel–Gasser–Ogden constitutive model. A single stiffness parameter was defined to characterize each ligament, with the anterior longitudinal ligament (ALL) being the stiffest, while the posterior longitudinal ligament and interspinous ligament (ISL) had the greatest variation. The posterior portion of the annulus fibrosis had the greatest stiffness and greatest variation up to 300% in circumferential loading. The resulting probabilistic representation can be utilized to include intersubject variability in biomechanics evaluations.

EFFECT OF RELATIVE DENSITY AND VELOCITY TOWARDS DYNAMIC RESPONSE OF METAL FOAM

2015 ◽  
Vol 76 (9) ◽  
Author(s):  
Mohd Azman Y. ◽  
Juri S. ◽  
Hazran H. ◽  
NorHafiez M. N. ◽  
Dong R.
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Theoretical Prediction ◽  
Relative Density ◽  
Impact Velocity ◽  
Impact Test ◽  
Metal Foam ◽  
Element Analysis ◽  
Static Tests ◽  
The Impact

Dynamic response of ALPORAS aluminium foam has been investigated experimentally and numerically. The dynamic response is quantified by the force produced as the foam deforms as a function of time. Quasi-static tests are conducted to determine the quasi-static properties of the foam. In the impact test, the aluminium foams are fired towards a rigid load-cell and the force signals developed are recorded. Experimental dynamic stress is also compared with theoretical prediction using existing theory. Finite element model is constructed using LS-DYNA to simulate the impact test. Results from the experiment, finite element analysis and theoretical prediction are in acceptable agreement. Finally, parametric studies have been conducted using the verified model to investigate the effect of impact velocity and relative density towards the dynamic response of the foam projectile. It is found that the dynamic response of the foam is more sensitive towards impact velocity as compare with the foam relative density.

scholarly journals Biaxial Tension of Fibrous Tissue: Using Finite Element Methods to Address Experimental Challenges Arising From Boundary Conditions and Anisotropy

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Nathan T. Jacobs ◽  
Daniel H. Cortes ◽  
Edward J. Vresilovic ◽  
Dawn M. Elliott
Keyword(s):  
Finite Element ◽  
Soft Tissue ◽  
Correction Factor ◽  
Mechanical Response ◽  
Biaxial Tension ◽  
Fibrous Tissue ◽  
Region Of Interest ◽  
Stress Concentrations ◽  
Applied Forces ◽  
The Impact

Planar biaxial tension remains a critical loading modality for fibrous soft tissue and is widely used to characterize tissue mechanical response, evaluate treatments, develop constitutive formulas, and obtain material properties for use in finite element studies. Although the application of tension on all edges of the test specimen represents the in situ environment, there remains a need to address the interpretation of experimental results. Unlike uniaxial tension, in biaxial tension the applied forces at the loading clamps do not transmit fully to the region of interest (ROI), which may lead to improper material characterization if not accounted for. In this study, we reviewed the tensile biaxial literature over the last ten years, noting experimental and analysis challenges. In response to these challenges, we used finite element simulations to quantify load transmission from the clamps to the ROI in biaxial tension and to formulate a correction factor that can be used to determine ROI stresses. Additionally, the impact of sample geometry, material anisotropy, and tissue orientation on the correction factor were determined. Large stress concentrations were evident in both square and cruciform geometries and for all levels of anisotropy. In general, stress concentrations were greater for the square geometry than the cruciform geometry. For both square and cruciform geometries, materials with fibers aligned parallel to the loading axes reduced stress concentrations compared to the isotropic tissue, resulting in more of the applied load being transferred to the ROI. In contrast, fiber-reinforced specimens oriented such that the fibers aligned at an angle to the loading axes produced very large stress concentrations across the clamps and shielding in the ROI. A correction factor technique was introduced that can be used to calculate the stresses in the ROI from the measured experimental loads at the clamps. Application of a correction factor to experimental biaxial results may lead to more accurate representation of the mechanical response of fibrous soft tissue.

scholarly journals Biomechanical Analysis of the Fixation System for T-Shaped Acetabular Fracture

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Yanping Fan ◽  
Jianyin Lei ◽  
Feng Zhu ◽  
Zhiqiang Li ◽  
Weiyi Chen ◽  
...  
Keyword(s):  
Finite Element ◽  
Acetabular Fracture ◽  
Element Model ◽  
Biomechanical Analysis ◽  
Anterior Column ◽  
Acetabular Fractures ◽  
Rigid Fixation ◽  
Optimal Method ◽  
System P ◽  
Fixation System

This study aims to evaluate the biomechanical mechanism of fixation systems in the most frequent T-shaped acetabular fracture using finite element method. The treatment of acetabular fractures was based on extensive clinical experience. Three commonly accepted rigid fixation methods (double column reconstruction plates (P × 2), anterior column plate combined with posterior column screws (P + PS), and anterior column plate combined with quadrilateral area screws (P + QS)) were chosen for evaluation. On the basis of the finite element model, the biomechanics of these fixation systems were assessed through effective stiffness levels, stress distributions, force transfers, and displacements along the fracture lines. All three fixation systems can be used to obtain effective functional outcomes. The third fixation system (P + QS) was the optimal method for T-shaped acetabular fracture. This fixation system may reduce many of the risks and limitations associated with other fixation systems.

A user-friendly finite element model for radial mode abrasive waterjet turning

2021 ◽  
pp. 095440542110173
Author(s):  
Y Abdelhameed ◽  
Ashraf I Hassan ◽  
Saleh Kaytbay
Keyword(s):  
Finite Element ◽  
Impact Velocity ◽  
Radial Mode ◽  
Abrasive Waterjet ◽  
Depth Of Cut ◽  
Fe Model ◽  
Abrasive Particles ◽  
Average Absolute Relative Error ◽  
User Friendly ◽  
The Impact

This paper aims to develop a finite element (FE) model precisely simulating the multi-particle impact in the radial mode abrasive waterjet turning (AWJT). An explicit dynamic analysis was carried out to predict the crater profile resulting from the impact of the abrasive particles along a limited segment of the jet pass over the workpiece surface. The effect of both momentum transfer loss and abrasive load ratio was taken into consideration while calculating the impact velocity of the abrasive particles. To build a user-friendly model, the scripting feature of ABAQUS was involved to automatically perform all the repetitive modeling procedures. The presented FE model considers four variable turning parameters tested at five levels each, including impact velocity, abrasive mass flow rate, traverse rate, and workpiece speed. The obtained crater profile from the simulation process was utilized to calculate the depth of cut (DOC) at different parameter combinations. A comparison between the numerical and experimental results shows a good agreement with an average absolute relative error of 9.74%.

Agricultural aircraft wing slat tolerance for bird strike

2017 ◽  
Vol 89 (4) ◽  
pp. 590-598 ◽  
Author(s):  
Adam Deskiewicz ◽  
Rafał Perz
Keyword(s):  
Finite Element ◽  
Impact Velocity ◽  
Structural Response ◽  
Element Model ◽  
Bird Strike ◽  
Element Analysis ◽  
Content Type ◽  
Explicit Finite Element ◽  
Explicit Finite Element Analysis ◽  
The Impact

Purpose The aim of this study is to assess and describe possible consequences of a bird strike on a Polish-designed PZL-106 Kruk agricultural aircraft. Due to its susceptibility to such events, a wing slat has been chosen for analysis. Design/methodology/approach Smooth particle hydrodynamics (SPH) formulation has been used for generation of the bird finite element model. The simulations were performed by the LS-Dyna explicit finite element analysis software. Several test cases have been analysed with differing parameters such as impact velocity, initial velocity vector direction, place of impact and bird mass. Findings Results of this study reveal that the structure remains safe after an impact at the velocity of 25 m/s. The influence of bird mass on slat damage is clearly observable when the impact velocity rises to 60 m/s. Another important finding was that in each case where the part did not withstand the applied load, it was the lug where first failure occurred. Some of the analysed cases indicated the possibility a consequent wing box damage. Practical implications This finding provides the manufacturer an important insight into the behaviour of the slat and suggests that more detailed analysis of the current lug design might improve the safety of the structure. Originality/value Even though similar analyses have been performed, they tended to focus on large transport aircraft components. This investigation will enhance our understanding of structural response of small, low-speed aircraft to a bird impact, which is a realistic scenario for the chosen case of an agricultural plane.

Parametric Study of Low Velocity Impact Using Finite Element Analysis

2013 ◽  
Vol 393 ◽  
pp. 397-402 ◽  
Author(s):  
Mohd Ridhuan Mohd Sahri ◽  
Che Muhamad Khairul Iezuadi Che Muhamad ◽  
Mohd Juzaila Abd Latif ◽  
Jamaluddin Mahmud
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Impact Velocity ◽  
Equivalent Plastic Strain ◽  
Low Velocity Impact ◽  
Skin Thickness ◽  
Low Velocity ◽  
Element Analysis ◽  
Material Response ◽  
The Impact

An aircraft structural and material response is very complex when subjected to impact. It involves both elastic and plastic deformation in instant. Nevertheless, investigating this phenomenon is challenging yet interesting. Therefore, this research attempts to investigate the effect of selected parameters variation (i.e. material type, skin thickness and impact velocity) to the resulting equivalent plastic shear strain using finite element analysis (FEA). The finite element (FE) models were developed using commercially modeling and FE software to replicate an aircraft fuselage (target) and projectile according to the experimental setup and data established by other researcher [. The current study only focuses on the materials response and deformation behavior due low velocity (30 150 m/s) impact of a blunt object to a square shape target made of Al 2024-T3 and aluminum alloy 7475 (AA 7475). In all cases (parameters variation), the resulting equivalent plastic strain has been determined and compared to the established data. It is found that the currents results are very close to the actual material response measured in experiments. This proves that simulated results are validated and the study contributed some knowledge to understanding the behaviour of the structural and material response in a low impact velocity. By varying selected parameters, the impact resistivity of the structure could be improved.

ANALYSES OF PEDESTRIAN’S HEAD-TO-WINDSHIELD IMPACT BIOMECHANICAL RESPONSES AND HEAD INJURIES USING A HEAD FINITE ELEMENT MODEL

2019 ◽  
Vol 20 (01) ◽  
pp. 1950063 ◽  
Author(s):  
ZHIHUA CAI ◽  
YUN XIA ◽  
XINGYUAN HUANG
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Impact Velocity ◽  
Inclination Angle ◽  
Head Injuries ◽  
Element Model ◽  
Head Model ◽  
Inclination Angles ◽  
Biomechanical Responses ◽  
The Impact

Head injuries in the vehicle crashes or pedestrian accidents can usually cause death or permanent disabilities, and head injuries resulting from the impact of car windshields remain a major problem. Anatomically, more realistic head models are required to more accurately document and evaluate the head-to-windshield impact responses and head injuries. The current study developed a head finite element model and carried out various simulations to investigate the head-to-windshield impact biomechanical responses and assess the head injuries. First, a 50th percentile three-dimensional finite element head model was developed and validated by using previously published cadaver experimental data. Then, the biomechanical responses were predicted under a head-to-windshield impact at different impact velocities (10, 12, and15[Formula: see text]m/s) and different inclination angles of the windshield (35∘, 40∘, and 45∘). Finally, head injuries were investigated through examining various injury parameters. The results indicated that the contact force, the acceleration, the intracranial pressure, the deformation of the skull, and the negative pressure rose when the impact velocity and the inclination angles increased. Thus, the vehicle impact velocity and the inclination angle of the windshield greatly affect the severity of the resulting injuries on pedestrians’ heads, with the severity increasing with the impact velocity and windshield inclination angle.

scholarly journals A life-cycle cost analysis of resilient flooring materials in acute-care facilities

2018 ◽  
Vol 7 (5) ◽  
pp. 70
Author(s):  
Deborah Wingler
Keyword(s):  
Life Cycle ◽  
Acute Care ◽  
Time Data ◽  
Total Cost Of Ownership ◽  
Total Cost ◽  
Cost Of Ownership ◽  
Real Time Data ◽  
The Impact ◽  
Flooring Materials ◽  
Flooring Material

Objective: This study compares the impact of maintenance protocols on coated and non-coated resilient flooring materials over the building life of an acute-care facility. The purpose of this study is to provide healthcare administrators, facility managers and designers with evidence regarding the total cost of ownership of different resilient flooring materials.Methods: Utilizing a life-cycle costing analysis (LCCA), a two-phase economic evaluation was conducted using both industry and real-time data collected from four health systems across three distinct geographic regions in the U.S. to evaluate the impact of coated and non-coated resilient flooring materials over the usable life of an acute-care facility.Results: Findings from both the first and second phase LCCA suggest that maintenance protocols can have a substantive impact on the total cost of ownership for resilient flooring materials due to the increase in operations and maintenance costs associated with a coated maintenance protocol. The point in time at which the factory applied finish failed for a non-coated flooring material was also shown to greatly contribute to the total cost of ownership.Conclusions: The use of real-time data, coupled with a systematic evaluation provided contextual information that proved essential to understanding some of the intricacies involved in resilient flooring maintenance protocols that can greatly influence economic outcomes. This approach supports an evidence-based decision making process for healthcare executives and environmental services staff to not only effectively evaluate new resilient flooring material selections, but to also proactively evaluate current maintenance protocols for increased monetary savings.

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