Comparison of Different Radial Basis Functions in Developing Subject-Specific Infant Head Finite Element Models for Injury Biomechanics Study

2012 ◽  
Author(s):  
Zhigang Li ◽  
Jingwen Hu ◽  
Jinhuan Zhang
Keyword(s):  
Finite Element ◽  
Interpolation Method ◽  
Fe Model ◽  
Mesh Quality ◽  
Injury Biomechanics ◽  
Shell Elements ◽  
Mesh Morphing ◽  
Subject Specific ◽  
Radial Basis ◽  
Spatial Interpolation Method

Developing a subject-specific finite element (FE) model, especially with only high quality hexahedral solid elements and quadrilateral shell elements, is very time-consuming. Recently, template-based mesh morphing method has become popular to construct subject-specific FE models, in which a baseline FE mesh can be morphed into a FE model with subject-specific geometry. Because the mesh morphing algorithm could be programmed and run automatically, it is a very promising method for future applications of subject-specific FE models in injury biomechanics studies. Radial Basis Function (RBF) as a powerful spatial interpolation method has already been used as a mesh morphing method (1). The types of RBFs can affect the morphed mesh quality and geometry accuracy in the RBF method. However, to date, no previous study has tried to compare the differences generated by different RBFs. Therefore, in this study, different RBFs were used to morph a baseline infant head FE model into 10 different subject-specific infant head FE models based on CT images from 10 children aged from 0 to 3 months. The mesh quality and geometry accuracy of the subject-specific models generated by different RBFs were compared using statistic analysis.

A Peak-Selection RBF Mesh Morphing Method for Subject-Specific Child Occupant Modeling

2018 ◽  
Author(s):  
Yunlei Yin ◽  
Wenxiang Dong ◽  
Zhenfei Zhan ◽  
Junming Li
Keyword(s):  
Finite Element ◽  
Motor Vehicle ◽  
Mesh Morphing ◽  
Subject Specific ◽  
Radial Basis ◽  
Occupant Injury ◽  
Optimal Kernel ◽  
Child Occupant ◽  
Specific Modeling ◽  
Important Significance

The mesh morphing method is widely applied in building subject-specific human finite element models. However, there are many problems yet to be resolved when applying the mesh morphing method in subject-specific modeling, such as calculation difficulties and low morphing accuracy. To solve these problems above, an efficient peak-selection RBF mesh morphing method is proposed in the paper. Firstly, by comparing different types of radial basis functions, an optimal kernel function is selected to improve morphing accuracy. Secondly, the landmarks are reduced by selecting multiple peak nodes from the object surfaces, so as to reduce iteration steps and improve the mesh generation efficiency. The proposed peak-selection Radial Basis Function (RBF) mesh morphing method is further demonstrated through a subject-specific child finite element modeling problem. This mesh morphing method has important significance for analyzing the occupant injury of different body features in motor vehicle crashes.

scholarly journals Design and Structural Analysis of a Rack System for Using in Agriculture

2018 ◽  
Vol 66 (3) ◽  
pp. 641-646
Author(s):  
Miroslav Blatnický ◽  
Ján Dižo ◽  
Dalibor Barta
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Structural Analysis ◽  
Fe Model ◽  
Steel Tubes ◽  
Shell Elements ◽  
Human Power ◽  
Construction Design ◽  
Pull Out ◽  
Pressure Pipeline

The paper deals with a construction design and structural analysis of the rack system which will be used for storage of steel tubes of pressure pipeline for fodder mixtures transportation in agricultural company. Structure of the designed equipment is made by the welding of steel parts and consists of the main framework and four pull-out racks on both sides. Racks move by means of human power through a rotating crank. Every individual pull-out racks is able to carries pipes of various dimensions, both length and diameter with total weight up to 3 tons with respect to customer requests. Since it is a prototype’s structure, we have designed main dimensions of it, material and technology for production and performed also structural analyses as the integral part of every engineering design. Structural analyses were conducted by means of numeric procedure known as finite element method. With respect to the used steel profiles shell elements were used for FE model. Analyses were performed for maximal loading cases in order to identify the level of safety in the most exposed locations of the structure.

Subject-Specific Finite Element Models of the Tibia With Realistic Boundary Conditions Predict Bending Deformations Consistent With In Vivo Measurement

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Ifaz T. Haider ◽  
Michael Baggaley ◽  
W. Brent Edwards
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Internal Rotation ◽  
Stress Fracture ◽  
Contact Forces ◽  
Female Participant ◽  
Fe Model ◽  
In Vivo Measurements ◽  
Subject Specific

Abstract Understanding the structural response of bone during locomotion may help understand the etiology of stress fracture. This can be done in a subject-specific manner using finite element (FE) modeling, but care is needed to ensure that modeling assumptions reflect the in vivo environment. Here, we explored the influence of loading and boundary conditions (BC), and compared predictions to previous in vivo measurements. Data were collected from a female participant who walked/ran on an instrumented treadmill while motion data were captured. Inverse dynamics of the leg (foot, shank, and thigh segments) was combined with a musculoskeletal (MSK) model to estimate muscle and joint contact forces. These forces were applied to an FE model of the tibia, generated from computed tomography (CT). Eight conditions varying loading/BCs were investigated. We found that modeling the fibula was necessary to predict realistic tibia bending. Applying joint moments from the MSK model to the FE model was also needed to predict torsional deformation. During walking, the most complex model predicted deformation of 0.5 deg posterior, 0.8 deg medial, and 1.4 deg internal rotation, comparable to in vivo measurements of 0.5–1 deg, 0.15–0.7 deg, and 0.75–2.2 deg, respectively. During running, predicted deformations of 0.3 deg posterior, 0.3 deg medial, and 0.5 deg internal rotation somewhat underestimated in vivo measures of 0.85–1.9 deg, 0.3–0.9 deg, 0.65–1.72 deg, respectively. Overall, these models may be sufficiently realistic to be used in future investigations of tibial stress fracture.

Development and Validation of Subject-Specific Finite Element Models for Blunt Trauma Study

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Weixin Shen ◽  
Yuqing Niu ◽  
Robert F. Mattrey ◽  
Adam Fournier ◽  
Jackie Corbeil ◽  
...  
Keyword(s):  
Finite Element ◽  
Ct Images ◽  
Fe Model ◽  
Rib Cage ◽  
Abdominal Organs ◽  
Subject Specific ◽  
Experimental Values ◽  
Thoracic And Abdominal ◽  
Development And Validation ◽  
Good Agreement

This study developed and validated finite element (FE) models of swine and human thoraxes and abdomens that had subject-specific anatomies and could accurately and efficiently predict body responses to blunt impacts. Anatomies of the rib cage, torso walls, thoracic, and abdominal organs were reconstructed from X-ray computed tomography (CT) images and extracted into geometries to build FE meshes. The rib cage was modeled as an inhomogeneous beam structure with geometry and bone material parameters determined directly from CT images. Meshes of soft components were generated by mapping structured mesh templates representative of organ topologies onto the geometries. The swine models were developed from and validated by 30 animal tests in which blunt insults were applied to swine subjects and CT images, chest wall motions, lung pressures, and pathological data were acquired. A comparison of the FE calculations of animal responses and experimental measurements showed a good agreement. The errors in calculated response time traces were within 10% for most tests. Calculated peak responses showed strong correlations with the experimental values. The stress concentration inside the ribs, lungs, and livers produced by FE simulations also compared favorably to the injury locations. A human FE model was developed from CT images from the Visible Human project and was scaled to simulate historical frontal and side post mortem human subject (PMHS) impact tests. The calculated chest deformation also showed a good agreement with the measurements. The models developed in this study can be of great value for studying blunt thoracic and abdominal trauma and for designing injury prevention techniques, equipments, and devices.

Rapid Visualization of Compressor Blade Finite Element Models Using Surrogate Modeling

2018 ◽  
Author(s):  
Spencer Bunnell ◽  
Christopher Thelin ◽  
Steven Gorrell ◽  
John Salmon ◽  
Christopher Ruoti ◽  
...  
Keyword(s):  
Finite Element ◽  
Design Process ◽  
Surrogate Modeling ◽  
Compressor Blade ◽  
Fe Model ◽  
Compressor Blades ◽  
Mesh Morphing ◽  
Training Samples ◽  
Time Required ◽  
The Impact

The design process for compressor blades is a highly iterative and often slow process. This research applied and measured the impact of using surrogates to quickly model the stresses on a compressor blade. By modeling distinct points on a finite element (FE) model with unique surrogates, the stress field of the entire FE model was quickly predicted. This required that the distinct points remain in the same relative location on each blade used in training the surrogate. This research studied the ability of mesh morphing, and using the surface nodes as those distinct points, to satisfy this requirement. The results show that mesh morphing performed well on the tested compressor blades. The research also found that the surrogate accuracy depended not only on the number of training samples, but also the number and types of parameters being emulated. The surrogate models achieved less than 5% error on all the tested blades. Finally, the method provided a 96% decrease in time required for a structural iteration of a compressor blade. Such speeds eliminate bottlenecks that may occur in the structural design process. The combination of mesh morphing and surrogate modeling in compressor blade analysis enables exploration of various geometric parameters and their effect on structural responses. Application of this process would produce a more thoroughly refined and understood compressor blade design.

Modelling cement augmentation: A comparative experimental and finite element study at the continuum level

2009 ◽  
Vol 224 (7) ◽  
pp. 903-911 ◽  
Author(s):  
Y Zhao ◽  
Z M Jin ◽  
R K Wilcox
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Computational Models ◽  
Image Data ◽  
Fe Model ◽  
Micro Computed Tomography ◽  
Synthetic Bone ◽  
Pmma Bone Cement ◽  
Subject Specific ◽  
Cent Error

Subject-specific computational models of anatomical components can now be generated from image data and used in the assessment of orthopaedic interventions. However, little work has been undertaken to model cement-augmented bone using these methods. The purpose of this study was to investigate different methods of representing a trabecular-like material (open-cell polyurethane foam, Sawbone, Sweden) augmented with poly(methyl methacrylate) (PMMA) bone cement in a finite element (FE) model. Three sets of specimens (untreated, fully augmented with cement, partially augmented with cement) were imaged using micro computed tomography (μCT) and tested under axial compression. Subject-specific continuum level FE models were built based on the μCT images. Using the first two sets of models, the material conversion factors between image greyscale and mechanical properties for the pure synthetic bone and cement-augmented composite were determined iteratively by matching the FE predictions to the experimental measurements. By applying these greyscale related mechanical properties to the FE models of the partially augmented specimens, the predicted stiffness was found to be more accurate (∼ 5 per cent error) than using homogeneous properties for the augmented and synthetic bone regions (∼ 18 per cent error). It was also found that the predicted stiffness using the modulus of pure cement to define the augmented region was overestimated, and generally the apparent elastic modulus was dominated by the properties of the synthetic bone.

Radial Basis Function Network (RBFN) Approximation of Finite Element Models for Real-Time Simulation

2011 ◽  
Author(s):  
Madusudanan Sathia Narayanan ◽  
Puneet Singla ◽  
Sudha Garimella ◽  
Wayne Waz ◽  
Venkat Krovi
Keyword(s):  
Neural Network ◽  
Finite Element ◽  
Real Time ◽  
Haptic Feedback ◽  
Radial Basis Function Network ◽  
High Temporal Resolution ◽  
Fe Model ◽  
Real Time Simulation ◽  
Time Simulation ◽  
Radial Basis

Nonlinearities inherent in soft-tissue interactions create roadblocks to realization of high-fidelity real-time haptics-based medical simulations. While finite element (FE) formulations offer greater accuracy over conventional spring-mass-network models, computational-complexity limits achievable simulation-update rates. Direct interaction with sensorized physical surrogates, in offline or online modes, allows a temporary sidestepping of computational issues but hinders parametric analysis and true exploitation of a simulation-based testing paradigm. Hence, in this paper, we develop Radial-Basis Neural-Network approximations, to FE-model data within a Modified Resource Allocating Network (MRAN) framework. Real-time simulation of the reduced order neural-network approximations at high temporal resolution provided the haptic-feedback. Validation studies are being conducted to evaluate the kinesthetic realism of these models with medical experts.

scholarly journals Trustworthiness in Modeling Unreinforced and Reinforced T-Joints with Finite Elements

2019 ◽  
Vol 24 (1) ◽  
pp. 27 ◽  
Author(s):  
Slimane Ouakka ◽  
Nicholas Fantuzzi
Keyword(s):  
Finite Element ◽  
Static Strength ◽  
Fe Model ◽  
Static Behavior ◽  
T Joints ◽  
Shell Elements ◽  
Mesh Density ◽  
Element Type ◽  
Material Discontinuities ◽  
Conclusion Section

As required by regulations, Finite Element Analyses (FEA) can be used to investigate the behavior of joints which might be complex to design due to the presence of geometrical and material discontinuities. The static behavior of such problems is mesh dependent, thus these results must be calibrated by using laboratory tests or reference data. Once the Finite Element (FE) model is correctly setup, the same settings can be used to study joints for which no reference is available. The present work analyzes the static strength of reinforced T-joints and sheds light on the following aspects: shell elements are a valid alternative to solid modeling; the best combination of element type and mesh density for several configurations is shown; the ultimate static strength of joints can be predicted, as well as when mechanical properties are roughly introduced for some FE topologies. The increase in strength of 12 unreinforced and reinforced (with collar or doubler plate) T-joints subjected to axial brace loading is studied. The present studies are compared with the literature and practical remarks are given in the conclusion section.

scholarly journals Comparison of Displacement-Based and Force-Based Mapped Meshing

2008 ◽  
Author(s):  
Vincent Magnotta ◽  
Wen Li ◽  
Nicole Grosland
Keyword(s):  
Finite Element ◽  
Distal Phalanx ◽  
Limiting Factors ◽  
Human Hand ◽  
Mesh Quality ◽  
Fe Method ◽  
Template Mesh ◽  
Subject Specific ◽  
Displacement Based ◽  
Time Required

The finite element (FE) method is a powerful tool for the study of biomechanics. One of the limiting factors in transitioning this tool into the clinic is the time required to generate high quality meshes for analysis. Previously, we developed a mapped meshing technique that utilized force control and a finite element solver to warp a template mesh onto subject specific surfaces. This paper describes a displacement based method that directly warps the template mesh onto subject specific surfaces using distance as the driving measure for the deformable registration. The resulting meshes were evaluated for mesh quality and compared to the force based method. An initial evaluation was performed using a mathematical phantom. The algorithm was then applied to generate meshes for the phalanx bones of the human hand. The algorithm successfully mapped the template bone to all of the bony surfaces, with the exception of the distal phalanx bone. In this one case, significant differences existed between the geometries of the template mesh and the distal phalanx. Further refinement of the algorithm may allow the algorithm to successfully generate meshes even in the presence of large geometric shape differences.

Finite Element Modeling of Bolted Cold-Formed Steel Storage Rack Upright Frames

2016 ◽  
Vol 846 ◽  
pp. 251-257
Author(s):  
Nima Talebian ◽  
Benoit P. Gilbert ◽  
Nadia Baldassino ◽  
Hong Guan
Keyword(s):  
Finite Element ◽  
Experimental Test ◽  
Transverse Shear ◽  
Shear Stiffness ◽  
Fe Model ◽  
Test Results ◽  
Shell Elements ◽  
Building Enclosure ◽  
Earthquake Design ◽  
Cold Formed Steel

Steel storage racks, commonly assembled from cold-formed steel profiles, are braced in the cross-aisle direction, where bracing members are typically bolted between two uprights forming an “upright frame”. Especially for high-bay racks and racks supporting the building enclosure, accurately determining the transverse shear stiffness of upright frames is essential in calculating the elastic buckling load, performing earthquake design and serviceability checks. International racking specifications recommend different approaches to evaluate the said transverse shear stiffness. The Rack Manufacturers Institute (RMI) Specification conservatively uses an analytical solution based on Timoshenko and Gere's theory while the European (EN15512) and Australian (AS4084) Specifications recommend testing to be conducted. Previous studies have shown that Finite Element Analyses (FEA), solely using beam elements, fail to reproduce experimental test results and may overestimate the transverse shear stiffness by a factor up to 25. This discrepancy is likely attributed to the local deformations occurring at the bolted joints. In this paper, a commercially used upright frame configuration has been modeled using shell elements in FEA and the response is verified against published experimental test results. A good correlation is found between the FEA and test results, concluding that shell elements are able to fully capture the behaviour of the upright frame. Future studies on the use of the FE model are also presented.

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