scholarly journals Stiffness modelling of flexible support module for Large-aperture laser transmission unit

2021 ◽  
Vol 2113 (1) ◽  
pp. 012069
Author(s):  
Jiabin Pan ◽  
Yanan Zhang ◽  
Zhongtao Fu ◽  
Linyong Shen
Keyword(s):  
Finite Element Method ◽  
Measurement Method ◽  
Compliant Mechanisms ◽  
Engineering Application ◽  
Average Error ◽  
Size Optimization ◽  
Large Aperture ◽  
Transmission Unit ◽  
Flexible Support ◽  
Stiffness Model

Abstract Large-aperture laser transmission unit (LLTU) is a device that focuses the laser beam to the center of the target, which are often designed as compliant mechanisms to achieve micro displacement adjustment. In the traditional mechanisms, they are designed as integrated micromanipulation systems, and driven by piezoelectric ceramics. However, most of these researches only focuses on motion accuracy, due to the lack of consideration of large load problems, the application is greatly limited. To this end, a flexible support module (FSM), as well as its stiffness model, was presented in this paper. Combined with finite element method (FEM) of FSM, structure size optimization was also completed, successfully solved the problems of stress concentration and load of FSM in engineering application. Moreover, a dual vision-based measurement method was introduced, to verify the stiffness model and analyze the repetitive error of FSM. From this result, the prototype enabled 5 mm and 0.007 rad of working area with average error of 0.3192 mm and -0.0036 rad. The repeatable error is within 7%, and will decreased to 4% with internal stress released in 5~15min.

scholarly journals Turbine Blade Three-Wavelength Radiation Temperature Measurement Method Based on Reflection Error Correction

2021 ◽  
Vol 11 (9) ◽  
pp. 3913
Author(s):  
Kaifeng Zheng ◽  
Jinguang Lü ◽  
Yingze Zhao ◽  
Jin Tao ◽  
Yuxin Qin ◽  
...  
Keyword(s):  
Temperature Measurement ◽  
Turbine Blade ◽  
Measurement Method ◽  
Turbine Blades ◽  
Target Surface ◽  
Maximum Error ◽  
Radiation Temperature ◽  
Average Error ◽  
Real Surface ◽  
Wavelength Radiation

The turbine blade is a key component in an aeroengine. Currently, measuring the turbine blade radiation temperature always requires obtaining the emissivity of the target surface in advance. However, changes in the emissivity and the reflected ambient radiation cause large errors in measurement results. In this paper, a three-wavelength radiation temperature measurement method was developed, without known emissivity, for reflection correction. Firstly, a three-dimensional dynamic reflection model of the turbine blade was established to describe the ambient radiation of the target blade based on the real surface of the engine turbine blade. Secondly, based on the reflection correction model, a three-wavelength radiation temperature measurement algorithm, independent of surface emissivity, was proposed to improve the measurement accuracy of the turbine blade radiation temperature in the engine. Finally, an experimental platform was built to verify the temperature measurement method. Compared with three conventional colorimetric methods, this method achieved an improved performance on blade temperature measurement, demonstrating a decline in the maximum error from 6.09% to 2.13% and in the average error from 2.82% to 1.20%. The proposed method would benefit the accuracy in the high-temperature measurement of turbine blades.

scholarly journals Non-Contact Respiration Measurement Method Based on RGB Camera Using 1D Convolutional Neural Networks

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3456
Author(s):  
Hyeon-Sang Hwang ◽  
Eui-Chul Lee
Keyword(s):  
Measurement Method ◽  
Respiratory Diseases ◽  
Region Of Interest ◽  
Average Error ◽  
Measurement Technology ◽  
Altman Analysis ◽  
Clinical Scenarios ◽  
Actual Environment ◽  
Error Bias ◽  
Robust To Noise

Conventional respiration measurement requires a separate device and/or can cause discomfort, so it is difficult to perform routinely, even for patients with respiratory diseases. The development of contactless respiration measurement technology would reduce discomfort and help detect and prevent fatal diseases. Therefore, we propose a respiration measurement method using a learning-based region-of-interest detector and a clustering-based respiration pixel estimation technique. The proposed method consists of a model for classifying whether a pixel conveys respiration information based on its variance and a method for classifying pixels with clear breathing components using the symmetry of the respiration signals. The proposed method was evaluated with the data of 14 men and women acquired in an actual environment, and it was confirmed that the average error was within approximately 0.1 bpm. In addition, a Bland–Altman analysis confirmed that the measurement result had no error bias, and regression analysis confirmed that the correlation of the results with the reference is high. The proposed method, designed to be inexpensive, fast, and robust to noise, is potentially suitable for practical use in clinical scenarios.

scholarly journals Analysis of influencing factors of flow state concrete mixture performance

2021 ◽  
Vol 2076 (1) ◽  
pp. 012073
Author(s):  
Dandan Shi ◽  
Xing Qin ◽  
Hao Qu
Keyword(s):  
Measurement Method ◽  
Engineering Application ◽  
Performance Testing ◽  
Reducing Agent ◽  
Mineral Admixture ◽  
Raw Material ◽  
Concrete Mixture ◽  
Flow State ◽  
Test Results ◽  
Concrete Mix

Abstract Based on the principle of benefiting the durability of concrete, machined sand is used to configure C40 flow concrete, and the engineering application environment and economy are considered. In this paper, the author through the flow state concrete mix ratio design, give the raw material dosage, concrete mixing, finally combined with the workability measurement method, five groups of concrete mix performance testing. According to the test results, the influence of mineral admixture and water reducing agent on the workability of concrete mixture is studied and analyzed, and the reasonable admixture dosage and water reducing rate of water reducing agent and its admixture dosage are finally given.

scholarly journals APPLICATION OF GALERKIN FINITE ELEMENT METHOD IN THE SOLUTION OF 3D DIFFUSION IN SOLIDS

2009 ◽  
Vol 8 (2) ◽  
pp. 79 ◽  
Author(s):  
E. C. Romão ◽  
M. D. De Campos ◽  
J. A. Martins ◽  
L. F. M. De Moura
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Solution ◽  
Heat Diffusion ◽  
Average Error ◽  
Galerkin Finite Element Method ◽  
Diffusion In Solids ◽  
Galerkin Finite Element ◽  
L2 Norm ◽  
Element Method

This paper presents the numerical solution by the Galerkin Finite Element Method, on the three-dimensional Laplace and Helmholtz equations, which represent the heat diffusion in solids. For the two applications proposed, the analytical solutions found in the literature review were used in comparison with the numerical solution. The results analysis was made based on the the L2 Norm (average error throughout the domain) and L¥ Norm (maximum error in the entire domain). The two application results, one of the Laplace equation and the Helmholtz equation, are presented and discussed in order to to test the efficiency of the method.

Failure Pressure Prediction of Cracks in Corrosion Defects Using XFEM

2020 ◽  
Author(s):  
Xinfang Zhang ◽  
Allan Okodi ◽  
Leichuan Tan ◽  
Juliana Leung ◽  
Samer Adeeb
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Extended Finite Element Method ◽  
Crack Depth ◽  
Average Error ◽  
Extended Finite Element ◽  
Defect Depth ◽  
Failure Pressure ◽  
Corrosion Defects ◽  
Element Method

Abstract Coating and cathodic protection degradation can result in the generation of several types of flaws in pipelines. With the increasing number of aging pipelines, such defects can constitute serious concerns for pipeline integrity. When flaws are detected in pipelines, it is extremely important to have an accurate assessment of the associated failure pressure, which would inform the appropriate remediation decision of repairing or replacing the defected pipelines in a timely manner. Cracks-in-corrosion (CIC) represent a class of defect, for which there are no agreed upon method of assessment, with no existing analytical or numerical models to predict their failure pressures. This paper aims to create a set of validated numerical finite element analysis models that are suitable for accurately predicting the failure pressure of 3D cracks-in-corrosion defects using the eXtended Finite Element Method (XFEM) technique. The XFEM for this study was performed using the commercially available software package, ABAQUS Version 6.19. Five burst tests of API 5L X60 specimens with different defect depths (varying from 52% to 66%) that are available in the literature were used to calibrate the XFEM damage parameters (the maximum principal strain and the fracture energy). These parameters were varied until a reasonable match between the numerical results and the experimental measurements was achieved. Symmetry was used to reduce the computation time. A longitudinally oriented CIC defect was placed at the exterior of the pipe. The profile of the corroded area was assumed to be semi-elliptical. The pressure was monotonically increased in the XFEM model until the crack or damage reached the inner surface of the pipe. The results showed that the extended finite element predictions were in good agreement with the experimental data, with an average error of 5.87%, which was less conservative than the reported finite element method predictions with an average error of 17.4%. Six more CIC models with the same pipe dimension but different crack depths were constructed, in order to investigate the relationship between crack depth and the failure pressure. It was found that the failure pressure decreased with increasing crack depth; when the crack depth exceeded 75% of the total defect depth, the CIC defect could be treated as crack-only defects, since the failure pressure for the CIC model approaches that for the crack-only model for ratios of the crack depth to the total defect depth of 0.75 and 1. The versatility of several existing analytical methods (RSTRENG, LPC and CorLAS) in predicting the failure pressure was also discussed. For the corrosion-only defects, the LPC method predicted the closest failure pressure to that obtained using XFEM (3.5% difference). CorLAS method provided accurate results for crack-only defects with 7% difference. The extended finite element method (XFEM) was found to be very effective in predicting the failure pressure. In addition, compared to the traditional Finite Element Method (FEM) which requires extremely fine meshes and is impractical in modelling a moving crack, the XFEM is computationally efficient while providing accurate predictions.

Measurement Method for Transmission Wavefront of Large Aperture Window

2016 ◽  
Vol 36 (8) ◽  
pp. 0812003
Author(s):  
刘强 Liu Qiang ◽  
徐晨 Xu Chen ◽  
李新南 Li Xinnan
Keyword(s):  
Measurement Method ◽  
Large Aperture

Elastave Bucking of Whole-Corrugate Web H-Beam

2011 ◽  
Vol 368-373 ◽  
pp. 23-27
Author(s):  
Yong Chen ◽  
Chun Yu Zhang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Cross Section ◽  
Engineering Application ◽  
Thin Wall ◽  
Constant Cross Section ◽  
Buckling Strength ◽  
Corrugated Web ◽  
Variable Section ◽  
H Beam

Contradiction between thin wall and stability of H-beam is a kind of problem in engineering field, the corrugated web H-beam researched in this paper relieve the contradiction to some extent. This paper apply finite element method of variable section beam and high programming language of MATLAB to analyze buckling strength under axis pressure and effect of critical load of parameter of whole-corrugated web H-beam and contrast to constant cross section H-beam, declaration superiority of whole-corrugated web H-beam with example, supply theory to this kind of H-beam in engineering application.

Dynamic Analysis and Design of Compliant Mechanisms Using the Finite Element Method

2012 ◽  
Vol 163 ◽  
pp. 111-115 ◽  
Author(s):  
Wen Jing Wang ◽  
Li Ge Zhang ◽  
Shu Sheng Bi
Keyword(s):  
Finite Element Method ◽  
Dynamic Model ◽  
Natural Frequency ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
The Finite Element Method ◽  
Dynamic Effects ◽  
Experiment System ◽  
Analysis And Design ◽  
Theoretical Results

Compliant mechanisms gain at least some of their mobility from the deflection of flexible members rather than from movable joints only. Dynamic effects are very important to improving the design of compliant mechanisms. An investigation on the dynamics and synthesis of the compliant mechanisms is presented. The dynamic model of compliant mechanisms is developed at first. The natural frequency and sensitivity are then studied based on the dynamic model. Finally, optimal design of compliant mechanism is investigated. The experimental study of natural frequency is performed. The comparison between the experiment results and the theoretical results verifies the validity of the experiment system and theoretical model.

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