scholarly journals ANALYSIS AND OPTIMAL DESIGN THE EFFECT OF DESIGN VARIABLES ON MAGANIFICATION RATIO OF A MAGANIFICATION MACHANISM EMPLOYING FLEXIBLE HINGE

2021 ◽  
Vol 45 (03) ◽  
Author(s):  
VAN- NANG DO
Keyword(s):  
Principal Stress ◽  
Compliant Mechanism ◽  
Maximum Principal Stress ◽  
Modal Shape ◽  
Element Analysis ◽  
Design Variables ◽  
Magnification Ratio ◽  
High Work ◽  
Good Agreement

In order to high work performant for compliant mechanism about motion scope, work long term and high frequency. Therefore, in this investigation displacement, maximum principal stress and the first modal shape frequency were analyzed by Finite element analysis (FEA) for a magnification mechanism to find out effects of design variables on magnification ratio of this mechanism. The FEA outcomes indicated that design variables have significantly affected on magnification ratio, maximum principal stress and the first modal shape frequency of a magnification mechanism. The magnification ratio obtained 42.83 times thereby maximum principal stress is equal to 132.79 MPa and the first modal shape frequency is equal to 377.44 Hz, respectively. The forecast results by the Taguchi method achieve a displacement of 0.4392 mm, and according to this method the optimal structure has a displacement of 0.4451 mm with the dimensions of the following variables: variable A is 0 mm, variable B is 23 mm and C is 60 mm, the parameters combine at the levels A1B2C1. This structure amplified 44.51 times, this result is a good agreement compared with the forecast results, the error compared to the forecast is 1.33%.the forecast results, the error compared to the forecast is 1.33%.

scholarly journals AN OPTIMUM FIRST MODAL SHAPE FREQUENCY FOR FLEXIBLE DISPLACEMENT AMPLIFIER MECHANISMS

2021 ◽  
Vol 45 (03) ◽  
Author(s):  
NGOC THAI HUYNH ◽  
TIEN V.T. NGUYEN
Keyword(s):  
Finite Element Analysis ◽  
Regression Analysis ◽  
Taguchi Method ◽  
Signal To Noise ◽  
Modal Shape ◽  
Element Analysis ◽  
Optimal Outcomes ◽  
Design Variables ◽  
Amplification Mechanism ◽  
Good Agreement

This investigation analyzed the influence of design variables of a new flexible hinge displacement amplification mechanism such as variable L, y, t, x on the first modal shape frequency of thismechanism. The Taguchi method is based on finite element analysis in ANSYS to optimize the first modal shape frequency of this mechanism. The FEA outcomes indicated that design variables have significantly affected the first modal shape frequency of this mechanism. And the problem was verified by analysis of variance, analysis of the signal to noise, and regression analysis of frequency. The optimal outcomes of frequency obtained 85.268 Hz. While the predicted outcomes of the frequency of the regression equation and the Taguchi method achieved 82.213 Hz and 82.459 Hz, these results are good agreement with error deviation percent of 3.47% and 3.29%, respectively.

scholarly journals Influence of fibromucosa height and loading on the stress distribution of a total prosthesis: a finite element analysis

2021 ◽  
Vol 24 (2) ◽  
Author(s):  
Tarcisio José de Arruda Paes Junior ◽  
João Paulo Mendes Tribst ◽  
Amanda Maria de Oliveira Dal Piva ◽  
Viviane Maria Gonçalves de Figueiredo ◽  
Alexandre Luiz Souto Borges ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Cortical Bone ◽  
Principal Stress ◽  
Maximum Principal Stress ◽  
Element Analysis ◽  
Total Displacement ◽  
Anterior Guidance ◽  
Mandibular Movements

Purpose: To evaluate the effect of fibromucosa height on the stress distribution and displacement of mandibular total prostheses during posterior unilateral load, posterior bilateral load and anterior guidance using the finite element analysis (FEA). Material and methods: 3D virtual models were made to simulate the stress generated during different mandibular movements in a total prosthesis. The contacts were simulated according to the physiology, being considered perfectly bonded between cortical and medullar bones; and between cortical bone and mucosa. Non-linear frictional contact was used for the total prosthesis base and fibromucosa, allowing the prosthesis to slide over the tissue. The cortical bone base was fixed and the 100 N load was applied as unilateral load, posterior bilateral load and anterior guidance simulation. The required results were for maximum principal stress (MPa), microstrain (mm/mm) and total displacement (mm). The numerical results were converted into colorimetric maps and arranged according to corresponding scales. Results: The stress generated in all situations was directly proportional to the fibromucosa height. The maximum principal stress results demonstrated greater magnitude for anterior guidance, posterior unilateral and posterior bilateral, respectively. Only posterior unilateral load demonstrated an increase in bone microstrain, regardless of the fibromucosa height. Prosthesis displacement was lower under posterior bilateral loading. Conclusion: Posterior bilateral loading is indicated for total prosthesis because it allows lower prosthesis displacement, lower stress concentration at the base of the prosthesis and less bone microstrain.   Keywords Finite element analysis; Occlusion; Total prosthesis.

Study on the Reduction Strategy of Machining-Induced Edge Chipping Based on Finite Element Analysis of In-Process Workpiece Structure

2013 ◽  
Vol 135 (1) ◽  
Author(s):  
Hu Gong ◽  
F. Z. Fang ◽  
X. F. Zhang ◽  
Juan Du ◽  
X. T. Hu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Principal Stress ◽  
Maximum Principal Stress ◽  
Machining Process ◽  
Element Analysis ◽  
Edge Chipping ◽  
Additional Support ◽  
The Relationship ◽  
Complex Parts

Edge chipping is one of the most serious issues during machining process of brittle materials. To find an effective method to reduce edge chipping, the relationship between the distribution of maximum principal stress and edge chipping is studied comprehensively based on 3D finite element analysis (FEA) model of in-process workpiece structure in this paper. Three-level influencing factors of edge chipping are proposed, which are helpful to understand the relationship between intuitive machining parameters and edge chipping at different levels. Based on the analysis, several experiments are designed and conducted for drilling and slotting to study the strategy of controlling edge chipping. Two methods are adopted: (a) adding additional support, (b) improving tool path. The result show that edge chipping can be reduced effectively by optimizing the distribution of the maximum principal stress during the machining process. Further, adding addtitional support method is extended to more complex parts and also obtain a good result. Finally, how to use adding additional support method, especially for complex parts, will be discussed in detail. Several open questions are raised for future research.

scholarly journals Predicting Silicon Die Breaking Force in Semiconductor Package Assembly through Mechanical Simulation

2021 ◽  
pp. 17-25
Author(s):  
Jefferson Talledo
Keyword(s):  
Loading Condition ◽  
Semiconductor Industry ◽  
Crack Problem ◽  
Cost Effective ◽  
Maximum Principal Stress ◽  
Assembly Process ◽  
Breaking Force ◽  
Element Analysis ◽  
Mechanical Simulation ◽  
Good Agreement

Die crack is a common problem in the semiconductor industry and being able to predict the breaking force at a given loading condition could help prevent such crack problem. This paper presents the use of mechanical simulation in predicting the force at which the silicon die breaks in semiconductor package assembly process. A computer simulation with finite element analysis (FEA) technique was used. The applied force or displacement in a die bending simulation with 3 mm, 4 mm and 15 mm support span was varied until the resulting maximum principal stress of the die becomes equal to its fracture strength. Results revealed that the breaking force for the 70 µm die with 6 mm width is around 5 N for the 3 mm support span and only around 1 N for the 15 mm support span. With the good agreement between modeling and actual results, the study showed that mechanical simulation is an effective approach in predicting die breaking force and can be used to simulate different mechanical loads in the package assembly where possible die crack could happen and be avoided. This is a fast and cost-effective way of assessing risk of die crack and obtaining package assembly process parameters and specifications that are safe to the silicon die.

Effects of the Mechanical Properties of Veneering Porcelain on Stress Distribution of Dental Zirconia Layered Structure: A Finite Element Model Study

2012 ◽  
Vol 512-515 ◽  
pp. 1797-1801
Author(s):  
Yuan Fu Yi ◽  
Long Quan Shao ◽  
Chen Wang ◽  
Ning Wen ◽  
Bin Deng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Stress Distribution ◽  
Principal Stress ◽  
Layered Structure ◽  
Geometric Model ◽  
Middle Layer ◽  
Maximum Principal Stress ◽  
Element Analysis ◽  
Occlusal Contact

The purpose of this study was to study effects of the mechanical properties of veneering porcelain on stress distribution of dental zirconia layered structure by three-dimensional finite element analysis. A 3-D geometric model of the first maxillary molar was established, a tooth preparation was simulated by the Imageware software. A crown was designed and divided into three layers: core, middle layer and outer veneer layer. The elasticity modulus of the middle layer was 70GPa for the control model up to 175GPa for the tested models. Loads of 200N were applied over a 1 mm diameter area beneath the tip of the mesial-distal cusp, simulating typical occlusal contact areas, the stress distribution of the crown systems were analyzed. Results show that within the geometry of the crown configuration, one concentration district of maximum principal stress occurred on the occlusal surface closely proximal to the loading position, several sub-maximum principal stress area were observed, such as margin regions of the mesial face, lingual face, distal faces, buccal face and occlusal fossa. Middle layer with higher modulus can effectively disperse the stress concentration in the layered zirconia all-ceramic crown system.

The Role of Fluid Dynamics in Distributing Ankle Stresses in Anatomic and Injured States

2016 ◽  
Vol 37 (12) ◽  
pp. 1343-1349 ◽  
Author(s):  
Kamran S. Hamid ◽  
Aaron T. Scott ◽  
Benedict U. Nwachukwu ◽  
Kerry A. Danelson
Keyword(s):  
Finite Element ◽  
Synovial Fluid ◽  
Principal Stress ◽  
Maximum Stress ◽  
High Stress ◽  
Distal Tibia ◽  
Element Model ◽  
Maximum Principal Stress ◽  
Ankle Injuries ◽  
Element Analysis

Background: In 1976, Ramsey and Hamilton published a landmark cadaveric study demonstrating a dramatic 42% decrease in tibiotalar contact area with only 1 mm of lateral talar shift. An increase in maximum principal stress of at least 72% is predicted based on these findings though the delayed development of arthritis in minimally misaligned ankles does not appear to be commensurate with the results found in dry cadaveric models. We hypothesized that synovial fluid could be a previously unrecognized factor that contributes significantly to stress distribution in the tibiotalar joint in anatomic and injured states. Methods: As it is not possible to directly measure contact stresses with and without fluid in a cadaveric model, finite element analysis (FEA) was employed for this study. FEA is a modeling technique used to calculate stresses in complex geometric structures by dividing them into small, simple components called elements. Four test configurations were investigated using a finite element model (FEM): baseline ankle alignment, 1 mm laterally translated talus and fibula, and the previous 2 bone orientations with fluid added. The FEM selected for this study was the Global Human Body Models Consortium–owned GHBMC model, M50 version 4.2, a model of an average-sized male (distributed by Elemance, LLC, Winston-Salem, NC). The ankle was loaded at the proximal tibia with a distributed load equal to the GHBMC body weight, and the maximum principal stress was computed. Results: All numerical simulations were stable and completed with no errors. In the baseline anatomic configuration, the addition of fluid between the tibia, fibula, and talus reduced the maximum principal stress computed in the distal tibia at maximum load from 31.3 N/mm2 to 11.5 N/mm2. Following 1 mm lateral translation of the talus and fibula, there was a modest 30% increase in the maximum stress in fluid cases. Qualitatively, translation created less high stress locations on the tibial plafond when fluid was incorporated into the model. Conclusions: The findings in this study demonstrate a meaningful role for synovial fluid in distributing stresses within the ankle that has not been considered in historical dry cadaveric studies. The increase in maximum stress predicted by simulation of an ankle with fluid was less than half that projected by cadaveric data, indicating a protective effect of fluid in the injured state. The trends demonstrated by these simulations suggest that bony alignment and fluid in the ankle joint change loading patterns on the tibia and should be accounted for in future experiments. Clinical Relevance: Synovial fluid may play a protective role in ankle injuries, thus delaying the onset of arthritis. Reactive joint effusions may also function to additionally redistribute stresses with higher volumes of viscous fluid.

scholarly journals Evaluation of the stress distribution in the cortical bone caused by variations in implant applications in patients with bruxism: A three-dimensional finite element analysis

2021 ◽  
Vol 11 (Suppl. 1) ◽  
pp. 194-200
Author(s):  
Yakup Kantaci ◽  
Sabiha Zelal Ülkü
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Cortical Bone ◽  
Principal Stress ◽  
Three Dimensional ◽  
Maximum Principal Stress ◽  
Element Analysis ◽  
Minimum Principal Stress ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Aim: To evaluate the stress distribution in the cortical bone under parafunctional forces with different occlusal thicknesses, monolithic zirconia with different implant diameters, and number variations in implant-supported fixed prosthetic restorations applied in patients with bruxism. Methodology: The tomographic sections of the previously registered mandible were used in order to model the mandible. Modeled bone height is 30 mm, cortical bone thickness is 1.5 mm, and trabecular bone thickness is modeled as 13 mm. By placing two implants in the created bone model, a three-member main model (Group 1), the number of implants was increased, three implants supported the Group 2 models, the diameter of the implants was increased, and the Group 3 models were created. The created Group 1, 2, 3 models, the occlusal thickness was divided into subgroups with 1.0, 1.5, and 2.0 mm, respectively (Groups A, B, and C). The groups were applied in two directions: vertical and 30o oblique. Stress values under forces were analyzed by finite element stress analysis. Results: Under vertical loading, the maximum principal stress value in the cortical bone was found to be lowest in Group 2C, and the highest maximum principal stress value was found in Group 1A. The minimum principal stress value in the cortical bone was found to be the lowest in Group 3C, and the highest minimum principal stress value was found in Group 1A. Under oblique loading, the maximum principal stress value in the cortical bone was found to be the lowest in Group 3C and the highest maximum principal stress value was found in Group 1A. The minimum principal stress value in the cortical bone was found to be lowest in Group 3C, and the highest minimum principal stress value was found in Group1A. Conclusion: Stresses caused by oblique forces are more than vertical forces. Increasing the occlusal thickness of the implant fixed prosthesis material, implant diameter, and number reduce the minimum and maximum principal stress values in the cortical   How to cite this article: Kantaci Y, Ülkü SZ. Evaluation of the stress distribution in the cortical bone caused by variations in implant applications in patients with bruxism: A three-dimensional finite element analysis. Int Dent Res 2021;11(Suppl.1):194-200. https://doi.org/10.5577/intdentres.2021.vol11.suppl1.27   Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Influence of Tapered Brittle Coatings on Stresses in Layered Structures: Relevance to Failure of Dental Crowns

2007 ◽  
Vol 334-335 ◽  
pp. 577-580
Author(s):  
Chris Ford ◽  
Tarek Qasim ◽  
Mark Bush ◽  
Xiao Zhi Hu
Keyword(s):  
Principal Stress ◽  
Contact Area ◽  
Maximum Principal Stress ◽  
Model Material ◽  
Dental Composite ◽  
Constant Thickness ◽  
Element Analysis ◽  
Balsa Wood ◽  
Dental Crowns ◽  
Stress Patterns

This paper uses Finite Element Analysis to examine stresses in loaded curved bi-layer structures. The model system consists of glass shells, both constant thickness and tapered, filled with dental composite. These systems, simulating brittle crowns on tooth dentine, are loaded with ultra-compliant disk indenters, and hard spherical indenters for comparison, along the (convex) axis of symmetry. The resulting maximum principal stress patterns are analysed. Previous studies have generally utilised hard spherical indenters of various radii indenting constant thickness coatings, and examined stresses leading to crack initiation. However, the peak stresses observed in this traditional contact problem – inducing surface cone cracking or flexureinduced radial cracking - occurred close to or inside the (small) contact area, and do not explain the margin failures in dental crowns commonly observed by dentists. Furthermore, the effect of varying coating thickness, especially tapering towards thinner margins, has not previously been examined. The use of an ultra-compliant indenter distributes the indentation force over a large contact area, generating a compressive zone underneath the contact, and consequently, previously insignificant stresses at the support margin become dominant, and the focus shifts to the support margin, rather than the area close to the contact. In this study, balsa wood is used as the disk indenter model material, with a modulus several orders of magnitude lower than the indented materials. Stress patterns from the same systems indented by hard spherical indenters are included for comparison. The specific focus is the effect of tapered coatings, examining stress patterns from several geometries. Results confirm not only a shift in the peak maximum principal stress from the near-contact area (under hard spherical indenters) to the margin area (under ultra-compliant indenters), but also show that coating taper can have a significant influence on the margin stress under a soft indenter. In the same systems indented by a hard indenter, coating taper has very little effect on the more localised stresses induced.

Interface Shape Effects on the Tensile Strength for T-type Structure Bonded Dissimilar Materials

2002 ◽  
Vol 17 (1) ◽  
pp. 20-25
Author(s):  
Shigeru Nagasawa ◽  
Yuji Yokoyama ◽  
Yasushi Fukuzawa ◽  
Masayoshi Tateno
Keyword(s):  
Tensile Strength ◽  
Principal Stress ◽  
Joint Angle ◽  
Dissimilar Materials ◽  
Maximum Principal Stress ◽  
Element Analysis ◽  
Shape Effects ◽  
The Relationship ◽  
Interface Edge ◽  
Spherical Interface

To estimate the effect of the spherical interface of the T-type joint structure on bonding strength, thermal residual stress on the outer surface and in the interface were investigated by thermal elastoplastic finite element analysis, in terms of principal stress and principal axis direction. These numerical results were compared with experimental fracture patterns and the tensile strength. The relationship between the maximum principal stress around the interface edge and the joint angle was studied. As a result,an optimal joint angle was shown by the experimental data and also by the principal stress calculated.

scholarly journals Influence of Fiber Post Cementation Length on Coronal Microleakage Values in vitro and Finite Element Analysis

2014 ◽  
Vol 15 (4) ◽  
pp. 444-450 ◽  
Author(s):  
César Dalmolin Bergoli ◽  
Rodrigo Furtado de Carvalho ◽  
Ivan Balducci ◽  
Josete Barbosa Cruz Meira ◽  
Maria Amélia Máximo de Araújo ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Principal Stress ◽  
Maximum Principal Stress ◽  
Fiber Post ◽  
Element Analysis ◽  
Mechanical Cycling ◽  
Fiber Posts

ABSTRACT Aim This study aims to evaluate, the influence of different fiber posts cementation lengths by finite element analysis (FEA) and coronal microleakage. Materials and methods Fifty anterior bovine teeth were sectioned to obtain roots with 16 mm length. The coronal length of the post was 6 mm for all groups, while the radicular length were varied 6, 8, 10 or 12 mm. The fiber posts surfaces were cleaned with alcohol and silanized. Then the posts were cemented using a two steps total etch-and-rinse adhesive system + conventional resin cement. Forty teeth were submitted to mechanical cycling (45°; 2.000.000 cycles; 90N; 4Hz; 37°C) and ten teeth with radicular length of 12 mm was not submitted, serving as control. So, the experimental design was composed by different ratios of post coronal length/post radicular length and mechanical cycling (MC): Gr1- 1/1 + MC; Gr2- 3/4 + MC; Gr3- 3/5 + MC; Gr4- 1/2 + MC. All groups were immersed in a 1% toluidine blue solution. After 24 hours, the teeth were longitudinally sectioned and the microleakage scores was given by a blind operator. Data were submitted to Kruskal-Wallis test (p = 0.05). The experimental variables were simulated in twodimensional finite element analysis (2D-FEA). The maximum principal stress distributions were compared. Results No difference was observed in microleakage values between the cycled groups, whilst the control groups showed the lowest values. FEA analysis showed similar maximum principal stress distribution between the groups. Conclusion Mechanical cycling affected the values of coronal microleakage and different cementation length generated similar values of coronal microleakage and stress distribution. Clinical significance These results showed that from the microleakage point of view, more conservative cementation lengths have the same effect as longer cementation lengths. How to cite this article Bergoli CD, de Carvalho RF, Balducci I, Meira JBC, de Araújo MAM, Valera MC. Influence of Fiber Post Cementation Length on Coronal Microleakage Values in vitro and Finite Element Analysis. J Contemp Dent Pract 2014; 15(4):444-450.

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