Comparison of the dynamic response of two columns of milling machines made of standard carpentry and metal foam sandwiches

2015 ◽  
Vol 23 (17) ◽  
pp. 2782-2794 ◽  
Author(s):  
M Portentoso ◽  
P Pennacchi ◽  
S Chatterton
Keyword(s):  
Dynamic Response ◽  
Metal Foam ◽  
Experimental Tests ◽  
Wide Frequency Range ◽  
Linear Behavior ◽  
Modal Damping ◽  
Wide Range ◽  
Milling Machines ◽  
Foam Filled ◽  
Mechanical Performances

In this paper, a comparison between two different machine tool columns is presented. The two columns are realized with a different technology: classic metalworking versus metal foam sandwiches. The aim of the experimental tests is the evaluation of their different mechanical performances and characteristics, with a particular focus on the dynamic response and on the convenience to consider system damping as a key parameter. This kind of comparison is generally believed as difficult, because the foam-filled structures usually show not-linear behavior, which makes not applicable the usual experimental modal procedures. The comparison is carried out in terms of both modal analysis and wide frequency range excitation, as described in the paper. A new method is introduced by the authors to deem which technology is the more suitable, based on overall dynamic response in a wide range of frequency, rather than on modal damping.

Novel Bulk Acoustic Wave Hammer to Determinate the Dynamic Response of Microstructures Using Pulsed Broad Bandwidth Ultrasonic Transducers

2001 ◽  
Author(s):  
Wen-Pin Lai ◽  
Yi-Ping Ho ◽  
Weileun Fang
Keyword(s):  
Acoustic Wave ◽  
Dynamic Response ◽  
Ultrasonic Transducer ◽  
Test Sample ◽  
Wide Frequency Range ◽  
Experimental Results ◽  
Bulk Acoustic Wave ◽  
Test Apparatus ◽  
Acoustic Coupling ◽  
Modal Damping

Abstract A novel testing technique to determinate the dynamic response of the microstructure is presented. In this study, a bulk acoustic wave hammer generated by a pulsed ultrasonic transducer is used to excite the microstructures. Thus the dynamic response of the microstructure in a wide frequency range is excited. Based on this novel method and test apparatus, the dynamic response of the microstructure including the resonant frequency, mode shape and the modal damping of the microstructure can be measured in a single excitation. Experimental results of the microbeams with different length agree well with theoretical predictions. In summary, the proposed BAW hammer technique has the following advantages. The sample preparation for this approach is very easy since it is not necessary to deposit an additional film for thermal or electrical purpose. In this regard, the experimental results of this technique are more accurate since there is no additional film to influence the dynamic behavior of the test sample. Moreover, there is no uncertain side effect such as thermal and acoustic coupling, caused by this approach. Since the test apparatus is also very simple, this approach has the potential to do the on-line test for batch production.

Dynamic Behavior of a Hydraulically Actuated Mechanism. Part 2: Nonlinear Character

1986 ◽  
Vol 108 (2) ◽  
pp. 250-254
Author(s):  
V. Venkatraman ◽  
R. W. Mayne
Keyword(s):  
Dynamic Response ◽  
Transient Response ◽  
Adequate Description ◽  
Linear Behavior ◽  
Transmission Angle ◽  
Dimensionless Groups ◽  
Hydraulically Actuated ◽  
Nonlinear Character ◽  
The Common ◽  
Nonlinear Nature

The first of these papers considering a hydraulically actuated mechanism presents the common oscillating cylinder arrangement and sets of equations which describe the dynamic system. It then defines dimensionless groups that characterize the actuator-mechanism and explores the quasi-linear behavior of the system. This present paper focuses on the nonlinear nature of the system. Effects of transmission angle, mechanism geometry and loading are considered as well as the range of operation in which the small perturbation behavior provides an adequate description of the dynamic response. The paper closes by identifying a new parameter which plays an important role in characterizing the dependence of the system transient response on mechanism geometry.

Effects of H2 Addition to CNG Blends on Cycle-to-Cycle and Cylinder-to-Cylinder Combustion Variation in an SI Engine

2012 ◽  
Author(s):  
Mirko Baratta ◽  
Stefano d’Ambrosio ◽  
Daniela Misul ◽  
Ezio Spessa
Keyword(s):  
Diagnostic Tool ◽  
Combustion Process ◽  
Experimental Tests ◽  
Test Point ◽  
Pollutant Emissions ◽  
Engine Operation ◽  
Pressure Transducers ◽  
Rate Analysis ◽  
Spark Plug ◽  
Wide Range

An experimental investigation and a burning-rate analysis have been performed on a production 1.4 liter CNG (compressed natural gas) engine fueled with methane-hydrogen blends. The engine features a pent-roof combustion chamber, four valves per cylinder and a centrally located spark plug. The experimental tests have been carried out in order to quantify the cycle-to-cycle and the cylinder-to-cylinder combustion variation. Therefore, the engine has been equipped with four dedicated piezoelectric pressure transducers placed on each cylinder and located by the spark plug. At each test point, in-cylinder pressure, fuel consumption, induced air mass flow rate, pressure and temperature at different locations on the engine intake and exhaust systems as well as ‘engine-out’ pollutant emissions have been measured. The signals correlated to the engine operation have been acquired by means of a National Instruments PXI-DAQ system and a home developed software. The acquired data have then been processed through a combustion diagnostic tool resulting from the integration of an original multizone thermodynamic model with a CAD procedure for the evaluation of the burned-gas front geometry. The diagnostic tool allows the burning velocities to be computed. The tests have been performed over a wide range of engine speeds, loads and relative air-fuel ratios (up to the lean operation). For stoichiometric operation, the addition of hydrogen to CNG has produced a bsfc reduction ranging between 2 to 7% and a bsTHC decrease up to the 40%. These benefits have appeared to be even higher for lean mixtures. Moreover, hydrogen has shown to significantly enhance the combustion process, thus leading to a sensibly lower cycle-to-cycle variability. As a matter of fact, hydrogen addition has generally resulted into extended operation up to RAFR = 1.8. Still, a discrepancy in the abovementioned conclusions was observed depending on the engine cylinder considered.

scholarly journals The Influence of Valve-Pump Weight Ratios on the Dynamic Response of Leaking Valve-Pump Parallel Control Hydraulic Systems

2018 ◽  
Vol 8 (7) ◽  
pp. 1201 ◽  
Author(s):  
Haigang Ding ◽  
Jiyun Zhao ◽  
Gang Cheng ◽  
Steve Wright ◽  
Yufeng Yao
Keyword(s):  
Dynamic Response ◽  
Hydraulic System ◽  
Weight Ratio ◽  
Open Loop ◽  
Hydraulic Systems ◽  
Variable Speed ◽  
Weight Factors ◽  
Wide Range ◽  
Parallel Control ◽  
Valve Control

A new leaking valve-pump parallel control (LVPC) oil hydraulic system is proposed to improve the performance of dynamic response of present variable speed pump control (VSPC) system, which is an oil hydraulic control system with saving energy. In the LVPC, a control valve is operating at leaking status, together with a variable speed pump, to regulate the system flow of hydraulic oil simultaneously. Therefore, the degree of valve control and pump control can be adjusted by regulating the valve-pump weight ratio. The LVPC system design, mathematical model development, system parameter and control performance analysis are carried out systematically followed by an experimental for validation process. Results have shown that after introducing the valve control, the total leakage coefficient increases significantly over a wide range with the operating point and this further increases damping ratios and reduces the velocity stiffness. As the valve-pump weight ratio determines the flow distribution between the valve and the pump and the weight factors of the valve and/or the pump controls determines the response speed of the LVPC system, thus if the weight factors are constrained properly, the LVPC system will eventually have a large synthetic open-loop gain and it will respond faster than the VSPC system. The LVPC will enrich the control schemes of oil hydraulic system and has potential value in application requiring of fast response.

Analysis and Characterization of Metal Foam-Filled Double-Pipe Heat Exchangers

2015 ◽  
Vol 68 (10) ◽  
pp. 1031-1049 ◽  
Author(s):  
Xi Chen ◽  
Fatemeh Tavakkoli ◽  
Kambiz Vafai
Keyword(s):  
Heat Exchangers ◽  
Metal Foam ◽  
Foam Filled ◽  
Double Pipe ◽  
Pipe Heat

scholarly journals Improving of electrical channels for magnetotelluric sounding instrumentation

2015 ◽  
Vol 4 (2) ◽  
pp. 149-154 ◽  
Author(s):  
A. M. Prystai ◽  
V. O. Pronenko
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Deep Structure ◽  
Experimental Tests ◽  
Magnetotelluric Sounding ◽  
Earth’S Crust ◽  
Geomagnetic Variations ◽  
The Earth ◽  
Wide Range ◽  
Earth's Crust

Abstract. The study of the deep structure of the Earth's crust is of great interest for both applied (e.g. mineral exploration) and scientific research. For this the electromagnetic (EM) studies which enable one to construct the distribution of electrical conductivity in the Earth's crust are of great use. The most common method of EM exploration is magnetotelluric sounding (MT). This passive method of research uses a wide range of natural geomagnetic variations as a powerful source of electromagnetic induction in the Earth, producing telluric current variations there. It includes the measurements of variations of natural electric and magnetic fields in orthogonal directions at the surface of the Earth. By this, the measurements of electric fields are much more complicated metrological processes, and, namely, they limit the precision of MT prospecting. This is especially complicated at deep sounding when measurements of long periods are of interest. The increase in the accuracy of the electric field measurement can significantly improve the quality of MT data. Because of this, the development of a new version of an instrument for the measurements of electric fields at MT – both electric field sensors and the electrometer – with higher levels relative to the known instrument parameter level – was initiated. The paper deals with the peculiarities of this development and the results of experimental tests of the new sensors and electrometers included as a unit in the long-period magnetotelluric station LEMI-420 are given.

scholarly journals 3D Printing Part 2 - A Literature Review Of 3D Printing Materials in Dentistry

2021 ◽  
Author(s):  
Adam Brian Nulty
Keyword(s):  
3D Printing ◽  
High Performance ◽  
Cost Effective ◽  
Future Evolution ◽  
Cost Effective Treatment ◽  
Wide Range ◽  
Milling Machines ◽  
Cad Cam ◽  
Subtractive Manufacturing ◽  
3D Printers

Introduction: The current generation of 3D printers are lighter, cheaper, and smaller, making them more accessible to the chairside digital dentist than ever before. 3D printers in general in the industrial and chairside setting can work with various types of materials including, metals, ceramics, and polymers. Evidence presented in many studies show that an ideal material used for dental restorations is characterised by several properties related to durability, cost-effectiveness, and high performance. This review is the second part in a 3D Printing series that looks at the literature on material science and applications for these materials in 3D printing as well as a discussion on the potential further development and future evolution in 3D printing materials. Conclusions: Current materials in 3D printing provide a wide range of possibilities for providing more predictable workflows as well as improving efficiency through less wasteful additive manufacturing in CAD/CAM procedures. Incorporating a 3D printer and a digital workflow into a dental practice is challenging but the wide range of manufacturing options and materials available mean that the dentist should be well prepared to treat patients with a more predictable and cost effective treatment pathway. As 3D printing continues to become a commonplace addition to chair side dental clinics, the evolution of these materials, in particular reinforced PMMA, resin incorporating zirconia and glass reinforced polymers offer increased speed and improved aesthetics that will likely replace subtractive manufacturing milling machines for most procedures.

scholarly journals Advanced Characterization of Bituminous Binders: Comparing Industrial and Paving-Grade Bituminous Binders

2021 ◽  
Vol 23 (1) ◽  
pp. 45
Author(s):  
S. Eskandarsefat ◽  
P. Caputo ◽  
C. Oliviero Rossi ◽  
R. Vaiana ◽  
C. Sangiorgi
Keyword(s):  
Great Influence ◽  
Experimental Tests ◽  
Advanced Characterization ◽  
Point Of View ◽  
Force Microscopy ◽  
Fundamental Factor ◽  
Chemical Structures ◽  
Wide Range ◽  
Significant Difference ◽  
Bituminous Binders

This paper deals with the fundamental differences between industrial and paving-grade bituminous binders. The paper is presented in two main sections: 1) a review of the materials’ colloidal structure and the required properties for the industrial and paving applications; 2) a wide range of experimental tests with which the bituminous binders were studied and compared. In this research, a 160/220 industrial bitumen was studied and compared to a paving-grade bitumen with the same penetration and with a lower penetration, 70/100 one. The research consisted of physical, chemical, thermal, microstructural, and rheological analysis to provide a comprehensive understanding of these bituminous binders of diverse applications. Overall, the comparison of the tests’ results indicated that while the asphaltene content and its characteristics have a great influence on the bitumen’s properties, it is not the only fundamental factor. During the study of the chemical structures via Atomic Force Microscopy (AFM), it was found that the Peri phase (attributed to the resins) also plays an important role, defining the bitumen’s physical visco-elastic properties. In fact, from a microstructural point of view using AFM a significant difference was notified between the industrial bitumen and the paving-grade ones. These differences allow the paving-grade bitumens to be more elastic and ductile compared to the industrial bitumen.

scholarly journals A Novel Method for Tuning PID Controller

2013 ◽  
Vol 6 (1) ◽  
pp. 62-74
Author(s):  
Abidaoun H. shallal ◽  
Rawaa A. Karim ◽  
Osama Y. Al-Rawi
Keyword(s):  
Computer Technology ◽  
Pid Control ◽  
Pid Controller ◽  
Control Algorithm ◽  
The Novel ◽  
Operation Conditions ◽  
Wide Range ◽  
Novel Method ◽  
Mechanical Performances ◽  
Dc Servomotor

Proportional integral derivative (PID) control is the most commonly used  control algorithm in the industry today. PID controller popularity can be attributed to the  controller’s effectiveness in a wide range of operation conditions, its functional simplicity, and the ease with which engineers can implement it using current computer technology . In this paper,the Dc servomotor model is chosen according to his good electrical and mechanical performances more than other Dc motor models , discuss the novel method for  tuning PID controller and comparison with Ziegler - Nichols method from through parameters of transient response of any system which uses PID compensator

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