Tolerance Analysis of Comb-Driving Double Ended Tuning Fork Resonator Fabricated by DRIE Technology

2014 ◽  
Vol 609-610 ◽  
pp. 1375-1380
Author(s):  
Rui Li Meng ◽  
Hong Qun Zhang ◽  
Heng Liu
Keyword(s):  
Resonance Frequency ◽  
Electrostatic Force ◽  
Tolerance Analysis ◽  
Design Stage ◽  
Positive Slope ◽  
Mechanical Stiffness ◽  
Lateral Direction ◽  
Deep Reactive Ion Etching ◽  
Comb Finger ◽  
Fabrication Tolerances

Deep reactive ion etching (DRIE) process is specially invented for bulk micromachining fabrication with the objective of realizing high aspect ratio microstructures. However, various tolerances, such as slanted etched profile, uneven deep beams and undercut, cannot be avoided during the fabrication process. In this paper, the slanted etched profile fabrication tolerance with its effect on the performances of lateral comb-driving resonator, in terms of electrostatic force, mechanical stiffness, and resonance frequency, are discussed. It shows that comb finger with positive slope generates larger electrostatic force. The mechanical stiffness along lateral direction increases when the suspended beam slants negatively. The resonance frequency is 1.116 times larger if the comb finger and beam are tapered to -20and + 20, respectively. These analytical results can be used to compensate the fabrication tolerances at design stage and allow the resonator to provide more predictable performance.

scholarly journals KARAKTERISTIK DINAMIKA STRUKTUR SATELIT MIKRO LAPAN-TUBSAT

2010 ◽  
Vol 3 (2) ◽  
Author(s):  
Robertus Heru Trihajanto ◽  
Sugiarmadji HPS
Keyword(s):  
Resonance Frequency ◽  
Dynamic Characteristic ◽  
Natural Frequency ◽  
Normal Modes ◽  
Longitudinal Direction ◽  
Mode Shapes ◽  
Al Alloy ◽  
Fem Modeling ◽  
Lateral Direction ◽  
Structural Dynamic

The TUBSAT-LAPAN micro satellite is planned to be launched using PSLV rocket. The design constraints of the mechanical system of the satellite are able to accomodate structural requirment for PSLV, which are first resonance frequency in the rocket longitudinal axis 90 Hz and first resonance frequency in the lateral axis 45 Hz. Therefore, the structural dynamic characteristic data of the satellite is important to be evaluated, such as natural frequency and mode shapes of the satellite structures, The normal modes analysis made is done usingh Finite Element Methods commercial software NASTRAN. To simplify the FEM modeling the satellite components inside the compartmens is replaced by a dummy load simulating their contribution to satellite mass, centerof gravity and inertia, which was made by the same material as the satellite's structure, i.e. Al-Alloy 2024T351. Meanwhile, the FEM modeling for both the UHF antena used the Stainless Steel materials as the real antena. The analysis results show that the lowest local natural frequency of the satellite occurs on the UHF antena. The first natural frequency of the antena structures in lateral direction is 52,29 Hz. The first natural frequency of the satellite in lateral direction 151.47 Hz completing the satellite integration, vibration test was done to the satellite. The test shows that the first global frequency is 72-75 Hz in the lateral direction and 148 Hz in longitudinal direction. Structural dynamic characteristic of TUBSAT_LAPAN micro satellite in free flying condition are also analyzed using no-constraint condition to check the safe separation clearance scenario. The results show that the first natural frequencies for satellite structures (combination) become very small, less than 0.00032 Hz. But, the lowest of the first natural frequency for UHF antena structures is almost constant, 52.30 Hz in lateral direction.

Fuzzy Sensitivity Analysis in the Context of Dimensional Management

2018 ◽  
Vol 5 (1) ◽  
Author(s):  
Thomas Oberleiter ◽  
Björn Heling ◽  
Benjamin Schleich ◽  
Kai Willner ◽  
Sandro Wartzack
Keyword(s):  
Tolerance Analysis ◽  
Design Stage ◽  
Special Focus ◽  
Total System ◽  
Early Design Stage ◽  
Technical Requirements ◽  
Geometric Deviations ◽  
Weak Points ◽  
Dimensional Management ◽  
The Impact

Real components always deviate from their ideal dimensions. This makes every component, even a serial production, unique. Although they look the same, differences can always be observed due to different scattering factors and variations in the manufacturing process. All these factors inevitably lead to parts that deviate from their ideal shape and, therefore, have different properties than the ideal component. Changing properties can lead to major problems or even failure during operation. It is necessary to specify the permitted deviations to ensure that every single product nevertheless meets its technical requirements. Furthermore, it is necessary to estimate the consequences of the permitted deviations, which is done via tolerance analysis. During this process, components are assembled virtually and varied with the uncertainties specified by the tolerances. A variation simulation is one opportunity to calculate these effects for geometric deviations. Since tolerance analysis enables engineers to identify weak points in an early design stage, it is important to know the contribution that every single tolerance has on a certain quality-relevant characteristic, to restrict or increase the correct tolerances. In this paper, a fuzzy-based method to calculate the sensitivity is introduced and compared with the commonly used extended Fourier amplitude sensitivity test (EFAST) method. Special focus of this work is the differentiation of the sensitivity for the total system and the sensitivities for the subsystems defined by the α-cuts of the fuzzy numbers. It discusses the impact of the number of evaluations and nonlinearity on sensitivity for EFAST and the fuzzy-based method.

Comparison of Different Sensitivity Analysis Methods in the Context of Dimensional Management

2017 ◽  
Author(s):  
Björn Heling ◽  
Thomas Oberleiter ◽  
Benjamin Schleich ◽  
Kai Willner ◽  
Sandro Wartzack
Keyword(s):  
Tolerance Analysis ◽  
Sensitivity Analyses ◽  
Design Stage ◽  
Fuzzy Arithmetic ◽  
Early Design Stage ◽  
Technical Requirements ◽  
Strongly Connected ◽  
Geometric Deviations ◽  
Comparison Of The Results ◽  
Dimensional Management

Although mass production parts look the same, every manufactured part is unique, at least on a closer inspection. The reason for this is that every manufactured part is inevitable subjected to different scattering influencing factors and variation in the manufacturing process, such as varying temperatures or tool wear. All these factors inevitably lead to parts, which deviate from their ideal shape. Products, which are built from these deviation-afflicted parts consequently show deviations from their ideal properties. To ensure that every single product nevertheless meets its technical requirements, it is necessary to specify the permitted deviations. Furthermore it is necessary to estimate the consequences of the permitted deviations, which is done via tolerance analysis. During this process the imperfect parts are assembled virtually and the effects of the geometric deviations can be calculated during a variation simulation. Since the tolerance analysis is to enable engineers to identify weak points in an early design stage it is important to know which contribution every single tolerance has on a certain quality-relevant characteristic, to restrict or increase the correct tolerances. In this paper two different approaches are shown and compared to represent the statistical behavior and the strongly connected sensitivity analyses. In particular a newly developed approach, which is based on fuzzy arithmetic, is compared to the established EFAST-method. The exemplary application of both methods and the comparison of the results are illustrated on a case study.

CAD-Based Tolerance Analysis in Preliminary Design Stages Enabling Early Tolerance Evaluation

2018 ◽  
Author(s):  
Stefan Goetz ◽  
Benjamin Schleich ◽  
Sandro Wartzack
Keyword(s):  
Tolerance Analysis ◽  
Design Stage ◽  
Preliminary Design ◽  
Design Changes ◽  
Preliminary Design Stage ◽  
Geometric Deviations ◽  
Set Up ◽  
Quality Of Products ◽  
Analysis Models

Associated with manufacturing and assembly processes, inevitable geometric deviations have a decisive influence on the function and quality of products. Therefore, their consideration and management are important tasks in product development. Moreover, to meet the demand for short development times, the front-loading of design processes is indispensable. This requires early tolerance analyses evaluating the effect of deviations in a design stage, where the product’s geometry has not yet been finally defined. Since such an early tolerance consideration allows quick and economic design changes seeking for robust designs, it is advisable that the design engineer, who is entirely familiar with the design, should take this step. For this purpose, this paper presents an easy-to-use CAD-based tolerance analysis method for skeleton models. The relevant part deviations are represented by varying geometric dimensions with externally driven family tables. The approach comprises the strength of vector-based methods but does not require an expensive set-up of tolerance analysis models. Particularly, the novelty of this method lies in the CAD-internal sampling-based tolerance analysis of simple geometries without the use of expensive CAT software. This enables designers to evaluate the effect of tolerances already at the preliminary design stage. Using a case study, the presented approach is compared with the conventional vector-based tolerance analysis.

scholarly journals Geometrical and dimensional tolerance analysis for the radial flux type of permanent magnet generator design

2021 ◽  
Vol 12 (2) ◽  
pp. 68-80
Author(s):  
Muhammad Fathul Hikmawan ◽  
Agung Wibowo ◽  
Muhammad Kasim
Keyword(s):  
Permanent Magnet ◽  
Manufacturing Process ◽  
Cumulative Effect ◽  
Tolerance Analysis ◽  
Air Gap ◽  
Tolerance Allocation ◽  
Design Stage ◽  
Worst Case ◽  
Radial Flux ◽  
Permanent Magnet Generator

Mechanical tolerance is something that should be carefully taken into consideration and cannot be avoided in a product for manufacturing and assembly needs, especially in the design stage, to avoid excessive dimensional and geometric deviations of the components made. This paper discusses how to determine and allocate dimensional and geometric tolerances in the design of a 10 kW, 500 rpm radial flux permanent magnet generator prototype components. The electrical and mechanical design results in the form of the detailed nominal dimensions of the generator components, and the allowable air gap range are used as input parameters for tolerance analysis. The values of tolerance allocation and re-allocation process are carried out by considering the capability of the production machine and the ease level of the manufacturing process. The tolerance stack-up analysis method based on the worst case (WC) scenario is used to determine the cumulative effect on the air gap distance due to the allocated tolerance and to ensure that the cumulative effect is acceptable so as to guarantee the generator's functionality. The calculations and simulations results show that with an air gap of 1 ± 0.2 mm, the maximum air gap value obtained is 1.1785 mm, and the minimum is 0.8 mm. The smallest tolerance value allocation is 1 µm on the shaft precisely on the FSBS/SRBS feature and the rotor on the RPMS feature. In addition, the manufacturing process required to achieve the smallest tolerance allocation value is grinding, lapping, and polishing processes.

NUMERICAL INVESTIGATION OF PUMP-TURBINES WITH DIFFERENT BLADES AT PUMP CONDITIONS

2012 ◽  
Vol 11 (02) ◽  
pp. 143-150 ◽  
Author(s):  
WEI LI ◽  
ZHONGYONG PAN ◽  
WEIDONG SHI
Keyword(s):  
Flow Rate ◽  
Rotating Stall ◽  
Low Flow ◽  
Design Stage ◽  
Positive Slope ◽  
Back Flow ◽  
Unsteady Simulation ◽  
Steady Simulation ◽  
Flow Vortex ◽  
Low Flow Rate

The undesirable performance of a positive slope curve usually appears for pump-turbines running as pumps at a low flow rate. The inner flow feature of pump-turbines with 6- and 7-blades runner is studied by both steady and unsteady simulations at pump conditions. According to the steady simulation investigation, obviously back flow vortex is found in the runner passage at the low flow rate zone where the positive slope curve forms. The flow rate at which the instable flow pattern happens of 6-blades runner is smaller than that of 7-blades one. By the unsteady simulation, at the low flow rate zone similar to the steady calculations and the tested data, a rotating stall with four rotating cells can be viewed by significant dynamic post-processing, whose rotation speed is much slower than that of the runner. Therefore, the back flow vortex of steady simulation and rotating stall of unsteady simulation can be used to investigate the runner quality at design stage.

Representing Geometric Viariations in Complex Structural Assemblies on CAD Systems

1992 ◽  
Author(s):  
Dari Shalon ◽  
David Gossard ◽  
Karl Ulrich ◽  
David Fitzpatrick
Keyword(s):  
Tolerance Analysis ◽  
Variation Method ◽  
Design Stage ◽  
Coordinate Systems ◽  
Index Point ◽  
Local Index ◽  
Solid Models ◽  
Engineering Changes ◽  
Complex Structural ◽  
The Individual

Abstract In previous airplane programs, Boeing identified interferences and misalignments between airplane parts as the two largest causes of engineering changes. Boeing is currently designing the 777 with a state-of-the-art solid modeling system. While the system is capable of detecting interferences and misalignments between ideally-sized and ideally-located solid models, it cannot model the effects of variation in the size, shape and location of parts and tools. This paper presents an initial, novel framework for modeling these variations called Indexed Pre-Assembly with Variation (IPAV). The main points made in this paper are: • Variations in both parts and tools should be modeled in exactly the same way. • Mating features of parts and tools can be represented in the solid models with local index-point coordinate systems. • Linking the mating index-point coordinate systems enables the positioning of the solid models in an assembly. • The order in which the index-point coordinate systems are linked corresponds to the planned assembly sequence. • The effects of size, shape and location variations on an assembly can be modeled by manipulating the index-point coordinate systems within the individual solid models. The academic literature on tolerancing and existing software tools for tolerance analysis are reviewed. A survey of Boeing engineers is presented which led to the development of the Indexed Pre-Assembly with Variation method. A case study involving an actual assembly problem at Boeing is analyzed with IPAV. The paper also discusses the benefits of simulating variation at the design stage and proposes an implementation plan to integrate IPAV into a generic airplane development schedule. Lastly, the applicability of IPAV to other industries is evaluated and areas for further research are identified.

Improvement of the Elastic Modulus of Micromachined Structures using Carbon Nanotubes

2005 ◽  
Vol 875 ◽  
Author(s):  
Prasoon Joshi ◽  
Nicolás B. Duarte ◽  
Abhijat Goyal ◽  
Awnish Gupta ◽  
Srinivas A. Tadigadapa ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Elastic Modulus ◽  
Resonance Frequency ◽  
Composite Layer ◽  
Average Increase ◽  
Mechanical Stiffness ◽  
Atomic Force ◽  
Bridge Structures ◽  
Walled Carbon Nanotubes ◽  
Force Displacement

AbstractMicroelectromechanical flexural structures have been fabricated using sandwiched multi-layers consisting of bundled singled walled carbon nanotubes(SWNTs) incorporated into silicon nitride (Si3N4) films. The Si3N4-SWNT composite layer was patterned by reactive ion etching followed by release in XeF2 to create freestanding bridge structures. The mechanical stiffness of the micromechanical bridges was monitored via force-displacement (F-D) curves obtained using an Atomic Force Microscope (AFM). Inclusion of SWNTs resulted in an increase in the spring constant of the bridge by as much as 64%, with an average increase of 25%. In a second experiment, micromachined bridges fabricated using dissolved wafer process were coated with debundled SWNTs. The SWNTs suspended in N-methyl-2-pyrrolidinone (NMP) solvent were sprayed locally on each bridge using a piezoelectric print head. Resonance frequency measurements were done in vacuum (∼10-4 Torr) on the bridges after successive SWNT depositions. A 20% increase in the resonance frequency of the bridges was observed. The observed increase in stiffness in the first set of experiments as well as the observed increase in the frequency in the second set of experiments can be attributed to the high axial modulus of elasticity (∼1 TPa) of the carbon nanotubes.

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