scholarly journals Spatially Resolved Experimental Modal Analysis on High-Speed Composite Rotors Using a Non-Contact, Non-Rotating Sensor

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4705
Author(s):  
Julian Lich ◽  
Tino Wollmann ◽  
Angelos Filippatos ◽  
Maik Gude ◽  
Juergen Czarske ◽  
...  
Keyword(s):  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Fiber Reinforced ◽  
Structural Dynamic ◽  
Spatially Resolved ◽  
Glass Fiber Reinforced ◽  
Vibration Responses ◽  
And Performance

Due to their lightweight properties, fiber-reinforced composites are well suited for large and fast rotating structures, such as fan blades in turbomachines. To investigate rotor safety and performance, in situ measurements of the structural dynamic behaviour must be performed during rotating conditions. An approach to measuring spatially resolved vibration responses of a rotating structure with a non-contact, non-rotating sensor is investigated here. The resulting spectra can be assigned to specific locations on the structure and have similar properties to the spectra measured with co-rotating sensors, such as strain gauges. The sampling frequency is increased by performing consecutive measurements with a constant excitation function and varying time delays. The method allows for a paradigm shift to unambiguous identification of natural frequencies and mode shapes with arbitrary rotor shapes and excitation functions without the need for co-rotating sensors. Deflection measurements on a glass fiber-reinforced polymer disk were performed with a diffraction grating-based sensor system at 40 measurement points with an uncertainty below 15 μrad and a commercial triangulation sensor at 200 measurement points at surface speeds up to 300 m/s. A rotation-induced increase of two natural frequencies was measured, and their mode shapes were derived at the corresponding rotational speeds. A strain gauge was used for validation.

Dynamic model for high-speed rotors based on their experimental characterization

2017 ◽  
Vol 2 (4) ◽  
pp. 25
Author(s):  
L. A. Montoya ◽  
E. E. Rodríguez ◽  
H. J. Zúñiga ◽  
I. Mejía
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Experimental Characterization ◽  
Rotating Systems ◽  
Computing Performance ◽  
The Impact ◽  
Stiffness Distribution ◽  
Good Agreement

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

Free Vibration Analysis of a Carbon Nanotube Reinforced Composite Beam

2014 ◽  
Vol 592-594 ◽  
pp. 2041-2045 ◽  
Author(s):  
B. Naresh ◽  
A. Ananda Babu ◽  
P. Edwin Sudhagar ◽  
A. Anisa Thaslim ◽  
R. Vasudevan
Keyword(s):  
Carbon Nanotube ◽  
Free Vibration ◽  
Composite Beam ◽  
Natural Frequencies ◽  
Equations Of Motion ◽  
Free Vibration Analysis ◽  
Mode Shapes ◽  
Element Formulation ◽  
Reinforced Composite ◽  
Vibration Responses

In this study, free vibration responses of a carbon nanotube reinforced composite beam are investigated. The governing differential equations of motion of a carbon nanotube (CNT) reinforced composite beam are presented in finite element formulation. The validity of the developed formulation is demonstrated by comparing the natural frequencies evaluated using present FEM with those of available literature. Various parametric studies are also performed to investigate the effect of aspect ratio and percentage of CNT content and boundary conditions on natural frequencies and mode shapes of a carbon nanotube reinforced composite beam. It is shown that the addition of carbon nanotube in fiber reinforced composite beam increases the stiffness of the structure and consequently increases the natural frequencies and alter the mode shapes.

scholarly journals An overview of NRL's NAUTILUS: a combination SIMS-AMS for spatially resolved trace isotope analysis

2020 ◽  
Vol 35 (3) ◽  
pp. 600-625 ◽  
Author(s):  
Evan E. Groopman ◽  
David G. Willingham ◽  
Albert J. Fahey ◽  
Kenneth S. Grabowski
Keyword(s):  
Research Laboratory ◽  
Isotope Analysis ◽  
Naval Research Laboratory ◽  
Naval Research ◽  
Spatially Resolved ◽  
Ultra Trace ◽  
And Performance ◽  
The U.S

We present a description of the capabilities and performance of the NAval Ultra-Trace Isotope Laboratory's Universal Spectrometer (NAUTILUS) at the U.S. Naval Research Laboratory, a combination SIMS-AMS for trace, in situ analyses.

scholarly journals Thermoplastic Reaction Injection Pultrusion for Continuous Glass Fiber-Reinforced Polyamide-6 Composites

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 463 ◽  
Author(s):  
Ke Chen ◽  
Mingyin Jia ◽  
Hua Sun ◽  
Ping Xue
Keyword(s):  
Mechanical Properties ◽  
Glass Fiber ◽  
High Speed ◽  
Flexural Modulus ◽  
Polyamide 6 ◽  
Thermoplastic Composites ◽  
Fiber Reinforced ◽  
Pultrusion Process ◽  
Glass Fiber Reinforced ◽  
Pultruded Composites

In this paper, glass fiber-reinforced polyamide-6 (PA-6) composites with up to 70 wt% fiber contents were successfully manufactured using a pultrusion process, utilizing the anionic polymerization of caprolactam (a monomer of PA-6). A novel thermoplastic reaction injection pultrusion test line was developed with a specifically designed injection chamber to achieve complete impregnation of fiber bundles and high speed pultrusion. Process parameters like temperature of injection chamber, temperature of pultrusion die, and pultrusion speed were studied and optimized. The effects of die temperature on the crystallinity, melting point, and mechanical properties of the pultruded composites were also evaluated. The pultruded composites exhibited the highest flexural strength and flexural modulus, reaching 1061 MPa and 38,384 MPa, respectively. Then, effects of fiber contents on the density, heat distortion temperature, and mechanical properties of the composites were analyzed. The scanning electron microscope analysis showed the great interfacial adhesion between fibers and matrix at 180 °C, which greatly improved the mechanical properties of the composites. The thermoplastic reaction injection pultrusion in this paper provided an alternative for the preparation of thermoplastic composites with high fiber content.

Micro-Drilling of CFRP Plates Using a High-Speed Spindle

2012 ◽  
Vol 523-524 ◽  
pp. 1035-1040 ◽  
Author(s):  
Keiji Ogawa ◽  
Heisaburo Nakagawa ◽  
Toshiki Hirogaki ◽  
Eiichi Aoyama
Keyword(s):  
Cutting Forces ◽  
High Speed ◽  
Fiber Reinforced ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastics ◽  
Cfrp Plate ◽  
Glass Fiber Reinforced ◽  
Reinforced Plastic ◽  
Micro Drilling ◽  
Fiber Reinforced Plastics

Fundamental characteristics in the micro drilling of carbon fiber reinforced plastic (CFRP) plates are investigated in the present paper. When micro drilling with a high-speed spindle, cutting forces during drilling, such as thrust force and torque, were measured by high resolution dynamometers and drill temperature was monitored by thermography. Comparing the experimental results of CFRP with that of drilling glass fiber-reinforced plastics (GFRP) revealed some unique tendencies. The cutting forces and drill temperature increased drastically. Moreover, drill wear rapidly accelerated. The tool life of CFRP plate drilling is much shorter than that of other plates.

scholarly journals Micromechanical modeling of 8-harness satin weave glass fiber-reinforced composites

2016 ◽  
Vol 51 (5) ◽  
pp. 705-720 ◽  
Author(s):  
RS Choudhry ◽  
Kamran A Khan ◽  
Sohaib Z Khan ◽  
Muhammad A Khan ◽  
Abid Hassan
Keyword(s):  
Finite Element ◽  
Glass Fiber ◽  
Material Properties ◽  
Micromechanical Model ◽  
Unit Cell ◽  
Micromechanical Modeling ◽  
Void Content ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced

This study introduces a unit cell-based finite element micromechanical model that accounts for correct post cure fabric geometry, in situ material properties and void content within the composite to accurately predict the effective elastic orthotropic properties of 8-harness satin weave glass fiber-reinforced phenolic composites. The micromechanical model utilizes a correct post cure internal architecture of weave, which was obtained through X-ray microtomography tests. Moreover, it utilizes an analytical expression to update the input material properties to account for in situ effects of resin distribution within yarn (the yarn volume fraction) and void content on yarn and matrix properties. This is generally not considered in modeling approaches available in literature and in particular, it has not been demonstrated before for finite element micromechanics models of 8-harness satin weave composites. The unit cell method is used to obtain the effective responses by applying periodic boundary conditions. The outcome of the analysis based on the proposed model is validated through experiments. After validation, the micromechanical model was further utilized to predict the unknown effective properties of the same composite.

scholarly journals Model Updating of Friction Stir Welding for Aluminium and Magnesium Plate Structure

2018 ◽  
Vol 150 ◽  
pp. 04004 ◽  
Author(s):  
Nazrotul Afina Nazri ◽  
Mohd Shahrir Mohd Sani ◽  
Muhammad Nasiruddin Mansor ◽  
Siti Norazila Zahari
Keyword(s):  
Friction Stir Welding ◽  
Natural Frequencies ◽  
Model Updating ◽  
Mode Shapes ◽  
Average Error ◽  
Element Analysis ◽  
Structural Dynamic ◽  
Friction Stir ◽  
Dissimilar Friction Stir Welding ◽  
Al 7075

Friction stir welding (FSW) of aluminium and magnesium alloys face high demands in automotive and aerospace application due to its advanced and lightweight properties. FSW is an emerging solid state joining process in which the material that is being welded does not melt and recast. The main objectives of this project are to perform model updating based on finite element analysis (FEA) and experimental modal analysis (EMA) of dissimilar material of aluminium alloy AL 7075 and magnesium alloy AZ 31B. Modal properties such as natural frequencies, mode shapes are obtained and compared between FEA and EMA. The discrepancies of first five modes natural frequencies are below than 10% and the model updating have been conducted to minimize the error between two methods. This model updating are based on sensitivity analysis in order to make sure which parameters are given more influence in this structural dynamic analysis. Young’s modulus and Poisson’s ratio both materials are selected in the model updating process. After perform model updating, total average error of the natural frequencies of dissimilar friction stir welding plate is improved significantly.

Microvia Formation for Multi-Layer PWB by Laser Direct Drilling: Improvement of Drilled Hole Quality of GFRP Plates

2012 ◽  
Author(s):  
Keiji Ogawa ◽  
Toshiki Hirogaki ◽  
Eiichi Aoyama ◽  
Tsukasa Ayuzawa
Keyword(s):  
High Speed ◽  
Fiber Reinforced ◽  
Hole Quality ◽  
Reinforced Plastics ◽  
Glass Fiber Reinforced ◽  
Via Holes ◽  
Overhang Length ◽  
Fiber Reinforced Plastics ◽  
Direct Drilling

Microvia formation technology using lasers has become the dominant method for drilling microvia that are called blind via-holes (BVHs) in printed wiring boards (PWBs). Laser direct drilling (LDD), which is direct drilling of the outer copper foil by laser, has attracted attention as a novel method. In particular, when copper and resin with different processing thresholds are simultaneously drilled, an overhang defect occurs on the drilled hole. On the other hand, aramid fiber reinforced plastics (AFRP) have been replaced by glass fiber reinforced plastics (GFRP) as the material used for the build-up layer because of its cost performance. Moreover, the PWB quality of the particle incrustations around the drilled holes has problems in the manufacturing process. However, the LDD process of such a composite has not been clarified. Therefore, we investigated it by detailed observation using a high-speed camera. We estimated the overhang length using the finite element method (FEM) and experimentally and analytically evaluated the effects of filler contented build-up layers. As a result, we improved drilled-hole quality by using prototype PWBs made of GFRP with filler in the build-up layer.

scholarly journals Comparative Studies between Precast and Conventional Cast-In-Situ Structural Systems

2021 ◽  
Vol 1197 (1) ◽  
pp. 012062
Author(s):  
Aman Agrawal ◽  
S.S. Sanghai ◽  
Kuldeep Dabhekar
Keyword(s):  
Comparative Studies ◽  
Concrete Structure ◽  
High Speed ◽  
Precast Concrete ◽  
Mode Shapes ◽  
Structural Systems ◽  
Seismic Loads ◽  
Time Frames ◽  
External Loads

Abstract In India, greatest constructional exercises are finished utilizing the old convectional cast in situ strategies since seemingly forever. As the nation is creating in a high speed, the necessity for lodging is heightening and in this way the development ventures are additionally blossoming quickly henceforth requesting quicker and better development techniques. This expanded interest can be coordinated by utilizing one of the cutting-edge innovations, pre-projected substantial strategy. Investigation of writing shows various priority of precast constructional strategy over different techniques for development. Appropriately, this investigation presents the examination and plan of g+5 floor precast concrete structure and traditional cast-in-situ structure. The designs were demonstrated and investigated utilizing Etabs programming for dead, forced, and seismic loads and for load combinations. The fundamental intention was to consider the conduct of both the sorts of structures under the previously mentioned loads and load mixes. Examination was directed dependent on different components like external loads, greatest deflections, most extreme story drifts, mode shapes, time-frames, frequencies and base shears.

In vivo structural dynamic analysis of the dragonfly wing: the effect of stigma as its modulator

2019 ◽  
Vol 377 (2150) ◽  
pp. 20190132 ◽  
Author(s):  
Amit Kumar ◽  
Navin Kumar ◽  
Rakesh Das ◽  
Piyush Lakhani ◽  
Bharat Bhushan
Keyword(s):  
Drag Coefficient ◽  
Natural Frequencies ◽  
Leading Edge ◽  
Micro Air Vehicles ◽  
Active Role ◽  
Image Correlation ◽  
Mode Shapes ◽  
Correlation Technique ◽  
Structural Dynamic

The flapping of the dragonfly forewing under in vivo condition has been analysed by image correlation technique to get an insight of its structural dynamics. The modal parameters such as flapping frequency, natural frequencies, mode shapes and modal strain have been obtained that will facilitate the biomimetic design of wings for micro air vehicles. The stigma, which is a pigmented spot at the leading edge of the wing near the tip having heavier mass, takes an active role in the real-time flapping by shaping its trajectory as eight-shaped, which enhances the drag coefficient and stroke efficiency. The extra mass on it and its removal transformed the trajectory into two different elliptical and oval shapes, respectively, which reduced the drag coefficient and stroke efficiency of the flapping wing by altering the flapping kinematics. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 2)’.

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