Microstructural Finite-Element Analysis of Influence of Bone Density and Histomorphometric Parameters on Mechanical Behavior of Mandibular Cancellous Bone Structure

2016 ◽  
Vol 258 ◽  
pp. 362-365 ◽  
Author(s):  
Petr Marcián ◽  
Zdeněk Florian ◽  
Ladislava Horáčková ◽  
Jozef Kaiser ◽  
Libor Borák

Using porous bioceramics became recently an alternative approach to increase bone density which is a key factor for successful dental implant application. These novel biomaterials should substitute missing natural trabecular structures in terms of material strength as well as deformation characteristics. However, mechanical behavior of these materials used as bone fillers are still in question. This problem is made more difficult by the fact that bone structure itself exhibits a complex mechanical behavior which is still in question as well and, therefore, appropriate analytical criteria should to be established. The purpose of this paper is to determine typical mechanical behavior of trabecular structure of mandibular cancellous bone using computational simulations which can serve as a basis for establishing such criteria. For this purpose, four bone specimens of various bone density were μCT-scanned and high-level finite element models including detailed trabecular structure were created on their basis to analyze relevant mechanical quantities for various loadings in terms of bone density and various histomorphometric parameters.

2013 ◽  
Vol 579-580 ◽  
pp. 866-872
Author(s):  
Qian Wang ◽  
Jin Song Bao ◽  
Chao Xun ◽  
Yi Jun Pan ◽  
Jun Jie Tang

The assembly of ship blocks is achieved through welding. To get a high level of closure accuracy, finite element analysis (FEA) is always needed to predict the welding deformation. However, the fast automatic mesh generation technique during the finite element method (FEM) for the ship assembly is not mature enough yet. Due to the complex ship architecture, during FEA, the model must be built up manually in most cases. This process is complicated and the errors are easy to occur. Consequently, the efficiency of FEA during the ship assembly is highly affected. Automatic mesh generation is a key factor restricting the development of FEM, since the quality and speed of the mesh generation directly influence the accuracy of calculation and the efficiency of analysis. In the field of marine engineering and aerospace engineering, the mesh elements are required to be quadrilateral. However, the technique of the quadrilateral mesh generation is still more difficult and less mature than that of the triangular mesh generation. This work proposed a hybrid mesh generation algorithm, borrowing the advantages from both the quad-morphing algorithm and the paving algorithm as well as considering the factor of multi-constraints. An example case is also given to illustrate the result of this proposed algorithm.


2017 ◽  
Vol 752 ◽  
pp. 11-17
Author(s):  
Florin Baciu ◽  
Aurelia Rusu-Casandra ◽  
Claudia Bratosin

The management of traumatic dental caries in primary teeth has the main objective to avoid their consequences that can affect the immediate and longterm quality of life of the child. Aggressive forms of decays can develop on smooth surfaces of teeth and progress rapidly, the effect being detrimental on the dentition. The objective of this study was to compare the stress and displacement distributions in the models of two assemblies by means of the three-dimensional finite element analysis: deciduous maxillary lateral incisor - restorative filling – bone structure and deciduous mandibular lateral incisor – restorative filling – bone structure respectively. Both models were subjected to a 120 N static load applied on the upper surface. The models were built from computed-tomography scans. Two different restorative dental materials were considered. In addition, the results obtained were compared with previous research of the authors, i.e. the mechanical behavior of a deciduous restored molar and deciduous restored canine respectively. As a result of the study, it can be concluded that the biomechanical analysis of deciduous dental caries is a valuable aid in enabling the dentist to make correct and effective treatment decisions.


Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1388
Author(s):  
Daniele Oboe ◽  
Luca Colombo ◽  
Claudio Sbarufatti ◽  
Marco Giglio

The inverse Finite Element Method (iFEM) is receiving more attention for shape sensing due to its independence from the material properties and the external load. However, a proper definition of the model geometry with its boundary conditions is required, together with the acquisition of the structure’s strain field with optimized sensor networks. The iFEM model definition is not trivial in the case of complex structures, in particular, if sensors are not applied on the whole structure allowing just a partial definition of the input strain field. To overcome this issue, this research proposes a simplified iFEM model in which the geometrical complexity is reduced and boundary conditions are tuned with the superimposition of the effects to behave as the real structure. The procedure is assessed for a complex aeronautical structure, where the reference displacement field is first computed in a numerical framework with input strains coming from a direct finite element analysis, confirming the effectiveness of the iFEM based on a simplified geometry. Finally, the model is fed with experimentally acquired strain measurements and the performance of the method is assessed in presence of a high level of uncertainty.


2000 ◽  
Vol 123 (1) ◽  
pp. 150-154
Author(s):  
John H. Underwood ◽  
Michael J. Glennon

Laboratory fatigue life results are summarized from several test series of high-strength steel cannon breech closure assemblies pressurized by rapid application of hydraulic oil. The tests were performed to determine safe fatigue lives of high-pressure components at the breech end of the cannon and breech assembly. Careful reanalysis of the fatigue life tests provides data for stress and fatigue life models for breech components, over the following ranges of key parameters: 380–745 MPa cyclic internal pressure; 100–160 mm bore diameter cannon pressure vessels; 1040–1170 MPa yield strength A723 steel; no residual stress, shot peen residual stress, overload residual stress. Modeling of applied and residual stresses at the location of the fatigue failure site is performed by elastic-plastic finite element analysis using ABAQUS and by solid mechanics analysis. Shot peen and overload residual stresses are modeled by superposing typical or calculated residual stress distributions on the applied stresses. Overload residual stresses are obtained directly from the finite element model of the breech, with the breech overload applied to the model in the same way as with actual components. Modeling of the fatigue life of the components is based on the fatigue intensity factor concept of Underwood and Parker, a fracture mechanics description of life that accounts for residual stresses, material yield strength and initial defect size. The fatigue life model describes six test conditions in a stress versus life plot with an R2 correlation of 0.94, and shows significantly lower correlation when known variations in yield strength, stress concentration factor, or residual stress are not included in the model input, thus demonstrating the model sensitivity to these variables.


2017 ◽  
Vol 103 (1) ◽  
pp. 196-205 ◽  
Author(s):  
Natalie E Cusano ◽  
Mishaela R Rubin ◽  
Barbara C Silva ◽  
Yu-Kwang Donovan Tay ◽  
John M Williams ◽  
...  

Abstract Context High-resolution peripheral quantitative computed tomography (HRpQCT) is a noninvasive imaging technology that can provide insight into skeletal microstructure and strength. In asymptomatic primary hyperparathyroidism (PHPT), HRpQCT imaging has demonstrated both decreased cortical and trabecular indices, consistent with evidence for increased fracture risk. There are limited data regarding changes in HRpQCT parameters postparathyroidectomy. Objective To evaluate changes in skeletal microstructure by HRpQCT in subjects with PHPT after parathyroidectomy. Design We studied 29 subjects with PHPT (21 women, 8 men) with HRpQCT at baseline and 6, 12, 18, and 24 months postparathyroidectomy. Main Outcome Measures Volumetric bone mineral density, microarchitectural indices, and finite element analysis at the distal radius and tibia. Results At both the radius and tibia, there were significant improvements in total, cortical, and trabecular volumetric bone density as early as 6 months postparathyroidectomy (24-month values for total volumetric bone density, radius: +2.8 ± 4%, tibia: +4.4 ± 4%; P < 0.0001 for both), cortical thickness (radius: +1.1 ± 2%, tibia: +2.0 ± 3%; P < 0.01 for both), and trabecular bone volume (radius: +3.8 ± 5%, tibia: +3.2 ± 4%; P < 0.0001 for both). At both sites, by finite element analysis, stiffness and failure load were improved starting at 6 months postparathyroidectomy (24-month values for failure load, radius: +6.2 ± 6%, tibia: +4.8 ± 7%; P < 0.0001 for both). Conclusions These results provide information about skeletal microarchitecture in subjects with PHPT followed through 2 years after parathyroidectomy. Estimated bone strength is improved, consistent with data showing decreased fracture risk postparathyroidectomy.


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