scholarly journals Efficient joint identification and fluted segment modelling of shrink-fit tool assemblies by updating extended tool models

2020 ◽  
Author(s):  
Christian Brecher ◽  
Prateek Chavan ◽  
Marcel Fey
Keyword(s):  
Frequency Response ◽  
Dynamic Behavior ◽  
Effective Diameter ◽  
Beam Model ◽  
The Real ◽  
Joint Properties ◽  
Joint Identification ◽  
Modelling Effort ◽  
Shrink Fit ◽  
Tool Assembly

AbstractIn milling, the dynamic behavior of the tool center point is crucial for estimating surface quality of the workpiece as well as the process stability behavior. Experimental-analytical receptance coupling can be used for predicting the tool tip dynamics but requires accurate analytical modelling of the holder-tool assembly. This includes the reliable identification of the holder-tool joint properties as well as the correct modelling of the fluted segment of end mills. However, the modelling effort associated with accurately representing the dynamic behavior of the fluted segment is significant. In addition, the joint identification requires a reference tool tip frequency response function of the tool assembly clamped in the machine spindle. This is inefficient and can also lead to incorrect estimation of joint properties. This paper provides an efficient method for joint identification and fluted section modelling using an offline, free–free excitation approach. The objective of this paper is to enable a direct comparison of the dynamic behavior of the freely constrained analytical tool assembly model with that of the real freely constrained tool assembly. The comparison of displacement to force frequency response at certain points on the tool assembly allows for the identification of tool model parameters such as the joint properties and effective diameter of the fluted segment. The comparability is realized by extending the analytical holder-tool beam model to include the receptance model of the standard spindle-holder interface. In this study, as an example, a thermal shrink-fit holder-tool beam model is extended to include an HSK-A63 interface. Subsequently, frequency response functions at two points on the real freely constrained tool assembly are measured in order to identify the joint stiffness and effective diameter of the fluted segment using the corresponding proposed formulations. The updated holder-tool model is then coupled with a 4-axis milling machine and validated. Despite the reduced modelling effort, a good prediction accuracy could be achieved for different holder-tool combinations.

scholarly journals Use of the Composite Properties of a Microwave Resonator to Enhance the Sensitivity of a Honey Moisture Sensor

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2549
Author(s):  
José R. Reyes-Ayona ◽  
Eloisa Gallegos-Arellano ◽  
Juan M. Sierra-Hernández
Keyword(s):  
Dielectric Permittivity ◽  
Frequency Response ◽  
Microwave Resonator ◽  
The Real ◽  
Moisture Sensor ◽  
Composite Resonator ◽  
Composite Properties

A moisture sensor based on a composite resonator is used to measure different honey samples, which include imitation honey. The sensor changes its frequency response in accordance with the dielectric permittivity that it detects in the measured samples. Although reflectometry sensors have been used to measure the percentage of moisture in honey for almost a century, counterfeiters have achieved that their apocryphal product is capable of deceiving these kinds of sensors. Metamaterial features of the composite resonators are expected to improve their response when detecting lossy samples such as organic samples. It is also sought that these sensors manage to detect small differences not only in the real parts of the dielectric permitivities of samples but also in their imaginary parts, and, thus, the sensors are able to discern between real honey and slightly altered honey. Effectively, not only was it possible to improve the response of the sensors by using lossy samples but it was also possible to identify counterfeit honey.

scholarly journals Dynamic Behavior of a Bidirectional Functionally Graded Sandwich Beam under Nonuniform Motion of a Moving Load

2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
Author(s):  
Dinh Kien Nguyen ◽  
An Ninh Thi Vu ◽  
Ngoc Anh Thi Le ◽  
Vu Nam Pham
Keyword(s):  
Dynamic Response ◽  
Dynamic Behavior ◽  
Moving Load ◽  
Sandwich Beam ◽  
Point Load ◽  
Functionally Graded ◽  
Beam Model ◽  
Material Distribution ◽  
Aspect Ratios ◽  
Nonuniform Motion

A bidirectional functionally graded Sandwich (BFGSW) beam model made from three distinct materials is proposed and its dynamic behavior due to nonuniform motion of a moving point load is investigated for the first time. The beam consists of three layers, a homogeneous core, and two functionally graded face sheets with material properties varying in both the thickness and longitudinal directions by power gradation laws. Based on the first-order shear deformation beam theory, a finite beam element is derived and employed in computing dynamic response of the beam. The element which used the shear correction factor is simple with the stiffness and mass matrices evaluated analytically. The numerical result reveals that the material distribution plays an important role in the dynamic response of the beam, and the beam can be designed to meet the desired dynamic magnification factor by appropriately choosing the material grading indexes. A parametric study is carried out to highlight the effects of the material distribution, the beam layer thickness and aspect ratios, and the moving load speed on the dynamic characteristics. The influence of acceleration and deceleration of the moving load on the dynamic behavior of the beam is also examined and highlighted.

The Generalized Response of Servovalve-Controlled, Single-Rod, Linear Actuators and the Influence of Transmission Line Dynamics

1984 ◽  
Vol 106 (2) ◽  
pp. 157-162 ◽  
Author(s):  
J. Watton
Keyword(s):  
Transmission Line ◽  
Frequency Response ◽  
System Design ◽  
Dynamic Behavior ◽  
Transmission Lines ◽  
Fatigue Testing ◽  
Open Loop ◽  
Linear Actuators ◽  
Probable Type

The open-loop response of servovalve-controlled single-rod linear actuators in investigated for both the extending and retracting cases. A linearized frequency response technique is used to establish the probable type of dynamic behavior. Nondimensional results are presented as an aid to system design, and a boundary is established such that a simplified approximation may be used. A particular class of system is then examined where interconnecting transmission lines would be important, and the techniques previously used are modified accordingly. The techniques are verified with a precision actuator developed for fatigue testing of vehicle and airframe systems.

Joint Parameters Identification of a Structure With Large Number of Discrete Joints

2003 ◽  
Author(s):  
J. H. Wang ◽  
S. C. Chuang
Keyword(s):  
Frequency Response ◽  
Dynamic Behavior ◽  
Error Function ◽  
Parameters Identification ◽  
New Method ◽  
Response Functions ◽  
Traditional Methods ◽  
Measured Frequency Response ◽  
Joint Parameters ◽  
Better Than

The joint parameters of a structure with a large number of discrete joints generally are very difficult to identify accurately. The difficulty is due to the fact that the dynamic behavior of a structure becomes more complex with more number of joints. A new identification method which uses the measured frequency response functions (FRFs) to identify the joint parameters is proposed in this work to overcome this difficulty. The new method uses an error function to select different best data to identify different joints so that the accuracy of the identification can be improved. The accuracy of the new method and other two traditional methods is compared in this work. The results show that the accuracy of the proposed new method is far better than other two previous methods. The proposed new method has special advantage when (1) the number of joints is large, (2) the orders of magnitude of the joint parameters are different significantly.

scholarly journals Limitations of a dynamic shear-frame model based in a small-scale experimental steel structure

2018 ◽  
Vol 211 ◽  
pp. 14005
Author(s):  
Augusto de S. Pippi ◽  
Pedro L. Bernardes Júnior ◽  
Suzana M. Avila ◽  
Marcus V. G. de Morais ◽  
Graciela Doz
Keyword(s):  
Dynamic Behavior ◽  
Geometric Modeling ◽  
Structural Model ◽  
Natural Frequencies ◽  
Numerical Models ◽  
Steel Structure ◽  
Small Scale ◽  
The Real ◽  
Frame Model ◽  
Shear Frame

Many engineering problems require geometric modeling and mechanical simulation of structures. Through the structural models, engineers try to simulate the real behavior of these structures. It is important that a model contain all the necessary parameters that describe the structure and its behavior during its useful life. In the field of dynamics, one of the most used models is the shear-frame, in which the stiffness of the structure is given by the stiffness of the columns and the whole mass is concentrated in the floor levels, which are considered with infinite stiffness. In some cases, this simplification offers more conservative results, which can lead to considerable errors, especially in the case of natural frequencies. Knowing that the quality of a structural model depends on the simplifications considered, an experimental 3D steel frame, constructed to typify the dynamic behavior of a tall building, was tested with a data acquisition system and accelerometers, in order to obtain its natural frequencies. In addition, a numerical model was developed in order to ascertain the results. These values of natural frequencies are compared with an idealized shear-frame model obtained from the experimental model. This comparison allows a critical analysis of the numerical models that can be employed to represent the real dynamic behavior of structures. The aim of the investigation is to show the results of the modal analysis for each model, comparing them with the experimental results and commenting their advantages and the limitations.

A study on the improvement of seismic coefficients for pseudo static analysis of gravity type quay wall via dynamic centrifuge tests

2020 ◽  
Author(s):  
Moon-Gyo Lee ◽  
Hyung-Ik Cho ◽  
Chang-Guk Sun ◽  
Han-Saem Kim
Keyword(s):  
Dynamic Behavior ◽  
Seismic Analysis ◽  
Inertial Force ◽  
Gravitational Acceleration ◽  
Ground Acceleration ◽  
Natural Period ◽  
The Real ◽  
Analysis And Design ◽  
Centrifuge Tests ◽  
Quay Wall

<p>The pseudo-static approach has been conventionally applied for the design of gravity type quay walls. In this method, the seismic coefficient (<em>k<sub>h</sub></em>), expressed in terms of acceleration due to gravity, is used to convert the real dynamic behavior to an equivalent pseudo-static inertial force for seismic analysis and design. The existing <em>k<sub>h</sub></em> is simply defined as the expected peak ground acceleration (<em>PGA</em>) of the ground divided by the gravitational acceleration (<em>g</em>), which does not sufficiently reflect the real dynamic behavior. In order to improve the <em>k<sub>h</sub></em> definition, a number of studies have been performed for reducing the differences between pseudo-static and true dynamic behavior. In this regard, questions regarding the need for considering the effect of frequency characteristics of input earthquake, natural period of the backfill soil and the subsoil underneath the wall, and wall height on the deformation of quay wall crown (<em>D<sub>h</sub></em>) have been explored. In this study, dynamic centrifuge tests were conducted using the gravity type quay wall models designed with a <em>k<sub>h</sub></em> value of 0.13 to assess the behavior of the model wall during earthquakes. Three different variables: input earthquake motions, wall heights and the thickness of subsoil underneath the wall were considered, and the test results were compared and analyzed to assess the validity of the conventional <em>k<sub>h</sub></em> concept under these conditions. In addition, some improvements that should be considered for the future revision of the <em>k<sub>h</sub></em> definition are discussed.</p>

Combined Frequency Equivalent Model for Power Transmission Network Dynamic Behavior Analysis

2018 ◽  
Vol 19 (2) ◽  
Author(s):  
S. Lakrih ◽  
J. Diouri
Keyword(s):  
Frequency Response ◽  
Behavior Analysis ◽  
Dynamic Behavior ◽  
Power Transmission ◽  
Equivalent Model ◽  
Network Dynamic ◽  
Transmission Network ◽  
Lumped Model ◽  
Distributed Parameters ◽  
The Impact

AbstractThis paper presents a dynamic equivalent model for transmission network dynamic behavior analysis in MATLAB SIMULINK. The electromagnetic frequency response and electromechanical response are combined in the model. The dynamic behavior of distributed parameters line modeled by the EMTP equivalent model is compared with that corresponding to lumped parameter line represented by π model. The aim is to define the frequency band in which the lumped model can accurately represent the distributed parameters model on no load conditions but also when the network is loaded. The proposed equivalent model is explored to investigate the impact of topology on the network dynamics. Besides, the influence of load nature and compensation rate on the driving point frequency response are analyzed analytically and simulated via the proposed model.

scholarly journals Real-Time Dynamic Behavior Evaluation of Active Distribution Networks Leveraging Low-Cost PMUs

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4999
Author(s):  
Xuejun Zheng ◽  
Shaorong Wang ◽  
Xin Su ◽  
Mengmeng Xiao ◽  
Zia Ullah ◽  
...  
Keyword(s):  
Real Time ◽  
Dynamic Behavior ◽  
Low Cost ◽  
Distribution Network ◽  
Distribution Networks ◽  
Assessment Model ◽  
The Real ◽  
Time Dynamic ◽  
Dynamic Index ◽  
Active Distribution Networks

The investigation of real-time dynamic behavior evaluation in the active distribution networks (ADNs) is a challenging task, and it has great importance due to the emerging trend of distributed generations, electric vehicles, and flexible loads integration. The advent of new elements influences the dynamic behavior of the electric distribution networks and increases the assessment complexity. However, the proper implementation of low-cost phasor measurement units (PMUs) together with the development of power system applications offer tremendous benefits. Therefore, this paper proposes a PMU-based multi-dimensional dynamic index approach for real-time dynamic behavior evaluation of ADNs. The proposed evaluation model follows the assessment principles of accuracy, integrity, practicability, and adaptability. Additionally, we introduced low-cost PMUs in the assessment model and implemented them for real-time and high-precision monitoring of dynamic behaviors in the entire distribution network. Finally, a complete model called the real-time dynamic characteristics evaluation system is presented and applied to the ADN. It is pertinent to mention that our proposed evaluation methodology does not rely on the network topology or line parameters of the distribution network since only the phasor measurements of node voltage and line current are involved in the dynamic index system. Thus, the presented methodology is well adaptive to different operation states of ADN despite frequent topology changes. The validation of the proposed approach was verified by conducting simulations on the modified IEEE 123-node distribution network. The obtained results verify the effectiveness and relevance of the proposed model for the real-time dynamic behavior evaluation of ADNs.

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