scholarly journals Parametric Study of the Centrifugal Insurance Mechanism in MEMS Safety and Arming Device

2017 ◽  
Author(s):  
Dakui Wang ◽  
Wenzhong Lou ◽  
Yue Feng ◽  
Fufu Wang
Keyword(s):  
Finite Element ◽  
Centrifugal Force ◽  
Parametric Study ◽  
Nonlinear Dynamic ◽  
Dynamic Method ◽  
Finite Element Models ◽  
Fem Model ◽  
Electromechanical Systems ◽  
Rotating Speed ◽  
Insurance Mechanism

MEMS (Micro-electromechanical Systems) becomes important increasingly due to the smarter and smaller fuze used in OICW (Objective Individual Combat Weapon). MEMS Safety and Arming (S&A) device is employed in different platforms and regions for small caliber projectile. Therefore, it is necessary to make a parametric study of the MEMS S&A device in different apply environments and explore the main sensitive factors of the MEMS S&A device to provide reference for designs. In this paper, based on the MEMS S&A device designed by our term, theory and finite element models are established, and the centrifugal insurance mechanism of the MEMS S&A device is parametric studied under the different speeds, temperature and thickness of the model by nonlinear dynamic method. By comparing the experimental and predicted results, the established FEM model is verified, and the conclusion is that the temperature and the centrifugal force are the main sensitive factors in the centrifugal insurance mechanism. In summary, we can suggest that the application environment, which the MEMS S&A device is suitable for, is the temperature equal to or slightly greater than normal temperature and the rotating speed higher than35000r/min of small caliber projectile.

Design and Strength Analysis of Ultra-High Speed Permanent Magnet DC Rotor

2011 ◽  
Vol 188 ◽  
pp. 481-486 ◽  
Author(s):  
J.C. Xiao ◽  
S.H. Xiao ◽  
H. Wu
Keyword(s):  
Finite Element ◽  
Centrifugal Force ◽  
High Speed ◽  
Rotational Velocity ◽  
Contact Theory ◽  
Strength Analysis ◽  
Interference Fit ◽  
Rotating Speed ◽  
Shrink Fitting ◽  
Nonmagnetic Steel

The sintered neodymium-iron-boron (Nd-Fe-B) material is used in most of PM machines. The kind of PM materials has small tensile strength and cannot withstand large centrifugal force due to high rotational velocity. A nonmagnetic steel enclosure is needed to cover the PM material. The tensile stress of the PM can reduced by pre-pressure applied to the outer surface of the PM through shrink-fitting into the enclosure. Based on the elasticity theory and the elastic-plastic contact theory, in soft ANSYS it is feasibility to establish a finite element mechanical model of interference fit between the enclosure and motor rotor PM at high rotating speed. This paper simulates the effects of the temperature and rotating speed (centrifugal force) on the displacement and the contact pressure on the interference-fitting surfaces .By finite element non-linear contact model analysis, if setting up right fit clearance, this paper could ensure the security of the PM rotor under rotational velocity up to 300,000 r/min high and temperature up to 150°C.

scholarly journals Increasing Damping of Thin-Walled Structures Using Additively Manufactured Vibration Eliminators

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2125 ◽  
Author(s):  
Paweł Dunaj ◽  
Stefan Berczyński ◽  
Karol Miądlicki ◽  
Izabela Irska ◽  
Beata Niesterowicz
Keyword(s):  
Finite Element ◽  
Dynamic Stiffness ◽  
Experimental Studies ◽  
Steel Beam ◽  
Finite Element Models ◽  
Fem Model ◽  
Thin Walled Structures ◽  
Resonance Frequencies ◽  
Thin Walled ◽  
Parametric Analyses

The paper presents a new way to conduct passive elimination of vibrations consisting of covering elements of structures with low dynamic stiffness with polylactide (PLA). The PLA cover was created in 3D printing technology. The PLA cover was connected with the structure by means of a press connection. Appropriate arrangement of the PLA cover allows us to significantly increase the dissipation properties of the structure. The paper presents parametric analyses of the influence of the thickness of the cover and its distribution on the increase of the dissipation properties of the structure. Both analyses were carried out using finite element models (FEM). The effectiveness of the proposed method of increasing damping and the accuracy of the developed FEM models was verified by experimental studies. As a result, it has been proven that the developed FEM model of a free-free steel beam covered with polylactide enables the mapping of resonance frequencies at a level not exceeding 0.6% of relative error. Therefore, on its basis, it is possible to determine the parameters of the PLA cover. Comparing a free-free steel beam without cover with its PLA-covered counterpart, a reduction in the amplitude levels of the receptance function was achieved by up to 90%. The solution was validated for a steel frame for which a 37% decrease in the amplitude of the receptance function was obtained.

Axial strength of steel circular hollow section (CHS) X-joints strengthened by flanged larger pipe

2020 ◽  
Vol 47 (3) ◽  
pp. 301-316
Author(s):  
Peter Gerges ◽  
Sameh Gaawan ◽  
Ashraf Osman
Keyword(s):  
Finite Element ◽  
Parametric Study ◽  
Thickness Ratio ◽  
Finite Element Models ◽  
T Joints ◽  
Hollow Section ◽  
Axial Strength ◽  
Structural Joints ◽  
Circular Hollow Section ◽  
Steel Design

In steel design, enhancing the structural joints’ capacity is considered a challenge that faces the designer. This challenge becomes more difficult when it comes to enhancing the capacities of circular hollow section (CHS) joints due to their closed nature that complicates the strengthening process. Recent research related to strengthening T-joints by utilizing two outer hollow ring flanges welded to additional pipe showed that this technique can significantly improve the joints’ strength. In this study, the utilization of this technique is extended for enhancing the axial strength of CHS X-joints. In this regard, a parametric study using finite element models was carried out to investigate the different design aspects that might affect the behavior of strengthened X-joints. The examined parameters included, the ring flange diameter, the stiffening pipe thickness and length for different brace diameter-to-chord diameter ratios and chord diameter to double chord thickness ratio. The results demonstrated that these strengthened X-joints gained significant axial strength that reached up to three times the axial strength of the unstrengthened joints. Guidelines for proper detailing of such strengthening scheme were provided. Finally, an equation that estimates the axial strength of strengthened joints was established based on the achieved results.

Penalty finite element models for nonlinear dynamic analysis

AIAA Journal ◽  
1986 ◽  
Vol 24 (2) ◽  
pp. 312-320 ◽  
Author(s):  
Ahmed K. Noor ◽  
Jeanne M. Peters
Keyword(s):  
Finite Element ◽  
Dynamic Analysis ◽  
Nonlinear Dynamic ◽  
Nonlinear Dynamic Analysis ◽  
Finite Element Models

scholarly journals A Finite Element Investigation into the Effect of Slope of Grain on Wood Baseball Bat Durability

2019 ◽  
Vol 9 (18) ◽  
pp. 3733 ◽  
Author(s):  
Joshua Fortin-Smith ◽  
James Sherwood ◽  
Patrick Drane ◽  
Eric Ruggiero ◽  
Blake Campshure ◽  
...  
Keyword(s):  
Finite Element ◽  
Wood Density ◽  
Wood Species ◽  
Parametric Study ◽  
Material Behavior ◽  
Finite Element Models ◽  
Ball Speed ◽  
Ball Impact ◽  
Fundamental Understanding ◽  
The Relationship

Bat durability is defined as the relative bat/ball speed that results in bat breakage, i.e., the higher the speed required to initiate bat cracking, the better the durability. In 2008, Major League Baseball added a regulation to the Wooden Baseball Bat Standards concerning Slope-of-Grain (SoG), defined to be the angle of the grain of the wood in the bat with respect to a line parallel to the longitudinal axis of the bat, as part of an overall strategy to reverse what was perceived to be an increasing rate of wood bats breaking into multiple pieces during games. The combination of a set of regulations concerning wood density, prescribed hitting surface, and SoG led to a 30% reduction in the rate of multi-piece failures. In an effort to develop a fundamental understanding of how changes in the SoG impact the resulting bat durability, a popular professional bat profile was examined using the finite element method in a parametric study to quantify the relationship between SoG and bat durability. The parametric study was completed for a span of combinations of wood SoGs, wood species (ash, maple, and yellow birch), inside-pitch and outside-pitch impact locations, and bat/ball impact speeds ranging from 90 to 180 mph (145 to 290 kph). The *MAT_WOOD (MAT_143) material model in LS-DYNA was used for implementing the wood material behavior in the finite element models. A strain-to-failure criterion was also used in the *MAT_ADD_EROSION option to capture the initiation point and subsequent crack propagation as the wood breaks. Differences among the durability responses of the three wood species are presented and discussed. Maple is concluded to be the most likely of the three wood species to result in a Multi-Piece Failure. The finite element models show that while a 0°-SoG bat is not necessarily the most durable configuration, it is the most versatile with respect to bat durability. This study is the first comprehensive numerical investigation as to the relationship between SoG and bat durability. Before this numerical study, only limited empirical data from bats broken during games were available to imply a qualitative relationship between SoG and bat durability. This novel study can serve as the basis for developing future parametric studies using finite element modeling to explore a large set of bat profiles and thereby to develop a deeper fundamental understanding of the relationship among bat profile, wood species, wood SoG, wood density, and on-field durability.

Parametric study of a VLSI plastic package using locally refined finite element models

1989 ◽  
Author(s):  
B.R. Simon ◽  
Y. Yuan ◽  
J.R. Umaretiya ◽  
J.L. Prince ◽  
Z.J. Staszak
Keyword(s):  
Finite Element ◽  
Parametric Study ◽  
Finite Element Models ◽  
Plastic Package

scholarly journals Experimental Validation of Finite Element Models for Reinforced Concrete Beams with Discontinuities That Form Dowel-Type Joints

Vibration ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 537-550
Author(s):  
Marios Filippoupolitis ◽  
Carl Hopkins
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Mode Shapes ◽  
Finite Element Models ◽  
Modal Assurance Criterion ◽  
Fem Model ◽  
Beam Elements ◽  
Concrete Elements

Earthquakes have the highest rate of mortality among the natural disasters and regularly lead to collapsed structures with people trapped inside them. When a reinforced concrete building collapses due to an earthquake, many of the concrete elements (i.e., beams and columns) are damaged and there are large sections where the concrete is missing and the steel reinforcement is exposed (i.e., concrete discontinuities). The prediction of vibration transmission in collapsed and severely damaged reinforced-concrete buildings could help decisions when trying to detect trapped survivors; hence there is need for experimentally validated finite element models of damaged concrete elements. This paper investigates the dynamic behaviour of damaged reinforced concrete beams using Experimental Modal Analysis (EMA) and Finite Element Methods (FEM). FEM models are assessed using two beams with one or more concrete discontinuities that form dowel-type joints. These models used either beam or spring elements for the exposed steel bars and were experimentally validated against EMA in terms of eigenfrequencies and mode shapes. Improved agreement was achieved when using springs instead of beam elements in the FEM model. The comparison of mode shapes used the Partial Modal Vector Ratio (PMVR) as a supplement to the Modal Assurance Criterion (MAC) to confirm that spring elements provide a more accurate representation of the response on all concrete parts of the beams.

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