scholarly journals ANALYSIS OF ANALYTICAL MODELS AND THE DEPENDENCES REALIZED BY THEM FOR DEFINITION OF MECHANICAL CHARACTERISTICS OF COMPOSITE FILLERS

2021 ◽  
Vol 1 (161) ◽  
pp. 8-18
Author(s):  
A. Kondratiev
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Elastic Modulus ◽  
Information Technologies ◽  
Mechanical Characteristics ◽  
Sandwich Structures ◽  
Accuracy Assessment ◽  
Analytical Models ◽  
Element Analysis ◽  
Shear Moduli

The analysis of the accuracy of analytical models and the mechanical properties they implement is carried out for various types of composite aggregates of sandwich structures. The accuracy assessment of approximate analytical dependencies of the mechanical characteristics of the composite honeycomb core is given. The applicability of analytical dependencies at the initial stages of the design of cellular structures is established. The accuracy of the results of a numerical experiment is noted. This is due to the approximate nature of standard test methods. Both for the elastic modulus and for the shear moduli, their values obtained on the basis of information technologies of finite element analysis exceed their corresponding values determined by analytical dependencies. This excess over the corresponding analytical values for the shear moduli is close to a constant value for various reinforcement angles and does not exceed 1.14. For the elastic modulus of the first kind, the excess varies from 1.03 to 1.8 for various angles of cell reinforcement. The analytical dependences of the reduced mechanical characteristics of the tubular aggregate are obtained. The idea of the method for determining the mechanical characteristics of a tubular filler is to fulfill the requirement of equality of the relative axial and shear deformations of a conventional continuous type element and a real one, selected within one tube, taking into account only its material. The conclusion is drawn that the mechanical characteristics of the tubular aggregate, determined by the analytical model, to different degrees differ from the corresponding characteristics obtained on the basis of information technology of finite element analysis. Moreover, the difference in the elastic moduli of the first kind is much smaller than in the shear moduli. The reasons for these discrepancies are analyzed. It is justified and recommended to use constant correction factors for the analytical values of the reduced mechanical characteristics of the tubular aggregate, allowing their further use in the calculation of plate and shell sandwich structures.

The equivalent method of double V-wing honeycombs on the in-plane dynamic impact

2021 ◽  
pp. 073168442199086
Author(s):  
Yunfei Qu ◽  
Dian Wang ◽  
Hongye Zhang
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Elastic Modulus ◽  
Energy Absorption ◽  
Width Ratio ◽  
Size Factor ◽  
Dynamic Impact ◽  
Element Analysis ◽  
Equivalent Method

The double V-wing honeycomb can be applied in many fields because of its lower mass and higher performance. In this study, the volume, in-plane elastic modulus and unit cell area of the double V-wing honeycomb were analytically derived, which became parts of the theoretical basis of the novel equivalent method. Based on mass, plateau load, in-plane elastic modulus, compression strain and energy absorption of the double V-wing honeycomb, a novel equivalent method mapping relationship between the thickness–width ratio and the basic parameters was established. The various size factor of the equivalent honeycomb model was denoted as n and constructed by the explicit finite element analysis method. The mechanical properties and energy absorption performance for equivalent honeycombs were investigated and compared with hexagonal honeycombs under dynamic impact. Numerical results showed a well coincidence for each honeycomb under dynamic impact before 0.009 s. Honeycombs with the same thickness–width ratio had similar mechanical properties and energy absorption characteristics. The equivalent method was verified by theoretical analysis, finite element analysis and experimental testing. Equivalent honeycombs exceeded the initial honeycomb in performance efficiency. Improvement of performance and weight loss reached 173.9% and 13.3% to the initial honeycomb. The double V-wing honeycomb possessed stronger impact resistance and better load-bearing capacity than the hexagonal honeycomb under impact in this study. The equivalent method could be applied to select the optimum honeycomb based on requirements and improve the efficiency of the double V-wing honeycomb.

scholarly journals Influence of Post and Resin Cement on Stress Distribution of Maxillary Central Incisors Restored with Direct Resin Composite

10.2341/08-73 ◽  
2009 ◽  
Vol 34 (2) ◽  
pp. 223-229 ◽  
Author(s):  
A. O. Spazzin ◽  
D. Galafassi ◽  
A. D. de Meira-Júnior ◽  
R. Braz ◽  
C. A. Garbin
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Elastic Modulus ◽  
Resin Composite ◽  
Resin Cement ◽  
Zirconia Ceramic ◽  
Element Analysis ◽  
Fiber Posts ◽  
Stress Levels ◽  
Glass Fiber Posts

Clinical Relevance According to finite element analysis, the zirconia ceramic post created higher stress levels in the post and slightly less in dentin compared with glass fiber posts. Resin cement with a high elastic modulus created higher stress levels in the cement layer. The different film thicknesses of cement did not create significant changes in stress levels.

scholarly journals A Study on Designing Balloon Expandable Magnesium Alloy Stent for Optimization of Mechanical Characteristics

Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 523
Author(s):  
Ichiro Shimizu ◽  
Akira Wada ◽  
Makoto Sasaki
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Study Design ◽  
Mechanical Characteristics ◽  
Design Parameters ◽  
Optimized Design ◽  
Element Analysis ◽  
Biodegradable Properties

Recently, the demand for a bio-absorbable coronary stent to promote recovery after an operation has increased. An option for such a stent is one made of a magnesium alloy, which has biodegradable properties. However, magnesium alloys have lower rigidity and lower ductility than other metals; as such, an appropriate stent structure is required to ensure radial rigidity. In this study, design parameters for an AZ31 magnesium alloy stent with sufficient radial rigidity were investigated. The necessary radial rigidity was determined by comparison tests against commercially available stents. The design parameters of the cell struts were selected and the optimum values to achieve high radial rigidity were investigated by means of elastic–plastic finite element analysis. Finally, a trial model stent based on the optimized design parameters was produced. It was confirmed that the model had sufficient radial rigidity, with no fracturing evident during crimping and expansion processes.

A 2-legged XY parallel flexure motion stage with minimised parasitic rotation

2014 ◽  
Vol 228 (17) ◽  
pp. 3156-3169 ◽  
Author(s):  
Guangbo Hao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Parallel Manipulator ◽  
Parallel Manipulators ◽  
Design Approach ◽  
Analytical Models ◽  
Geometrical Parameters ◽  
Element Analysis ◽  
Motion Range ◽  
Cross Axis

XY compliant parallel manipulators (aka XY parallel flexure motion stages) have been used as diverse applications such as atomic force microscope scanners due to their proved advantages such as eliminated backlash, reduced friction, reduced number of parts and monolithic configuration. This paper presents an innovative stiffness centre based approach to design a decoupled 2-legged XY compliant parallel manipulator in order to better minimise the inherent parasitic rotation and have a more compact configuration. This innovative design approach makes all of the stiffness centres, associated with the passive prismatic (P) modules, overlap at a point that all of the applied input forces can go through. A monolithic compact and decoupled XY compliant parallel manipulator with minimised parasitic rotation is then proposed using the proposed design approach based on a 2-PP kinematically decoupled translational parallel manipulator. Its load–displacement and motion range equations are derived, and geometrical parameters are determined for a specified motion range. Finite element analysis comparisons are also implemented to verify the analytical models with analysis of the performance characteristics including primary stiffness, cross-axis coupling, parasitic rotation, input and output motion difference and actuator nonisolation effect. Compared with the existing XY compliant parallel manipulators obtained using 4-legged mirror-symmetric constraint arrangement, the proposed XY compliant parallel manipulators based on stiffness centre approach mainly benefits from fewer legs resulting in reduced size, simpler modelling as well as smaller lost motion. Compared with existing 2-legged designs with the conventional arrangement, the present design has smaller parasitic rotation, which has been proved from the finite element analysis results.

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