Determining Material Properties of Nonlinear Materials From Transient Response

2007 ◽  
Author(s):  
Shad A. Reed ◽  
Anthony N. Palazotto ◽  
William Baker
Keyword(s):  
Material Properties ◽  
Hard Coatings ◽  
Complete Agreement ◽  
Nonlinear Phenomenon ◽  
Load History ◽  
Free Response ◽  
Nonlinear Materials ◽  
Depth Study ◽  
Stiffness And Damping ◽  
Damping Treatments

Several researchers have shown that the material properties of hard coatings used in free layer damping treatments are dependent on the strain amplitude in the coating. This nonlinear phenomenon complicates the material characterization process and makes it difficult to find independent sets of data that are in complete agreement. During a recent in depth study of these materials, it became apparent that there were several other time and load history dependent nonlinearities present in these fascinating materials. These nonlinearities were observable because a free response based testing methodology was employed. Results indicate that the stiffness and damping of these materials change during the first several million loading cycles before finally stabilizing. Additionally, results suggest that the material properties are dependent on the initial condition of the free response, indicating a short term loading history dependency.

scholarly journals Liquid Metal-Based Devices: Material Properties, Fabrication and Functionalities

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3400
Author(s):  
Jian Dong ◽  
Yuanyuan Zhu ◽  
Zhifu Liu ◽  
Meng Wang
Keyword(s):  
Liquid Metal ◽  
Material Properties ◽  
Flow Characteristics ◽  
Strain Sensors ◽  
Electrical Stability ◽  
Nonlinear Materials ◽  
Capillary Method ◽  
Communication Device ◽  
Fluid Properties ◽  
Manufacturing Techniques

This paper reviews the material properties, fabrication and functionalities of liquid metal-based devices. In modern wireless communication technology, adaptability and versatility have become attractive features of any communication device. Compared with traditional conductors such as copper, the flow characteristics and lack of elastic limit of conductive fluids make them ideal alternatives for applications such as flexible circuits, soft electronic devices, wearable stretch sensors, and reconfigurable antennas. These fluid properties also allow for innovative manufacturing techniques such as 3-D printing, injecting or spraying conductive fluids on rigid/flexible substrates. Compared with traditional high-frequency switching methods, liquid metal (LM) can easily use micropumps or an electrochemically controlled capillary method to achieve reconfigurability of the device. The movement of LM over a large physical dimension enhances the reconfigurable state of the antenna, without depending on nonlinear materials or mechanisms. When LM is applied to wearable devices and sensors such as electronic skins (e-skins) and strain sensors, it consistently exhibits mechanical fatigue resistance and can maintain good electrical stability under a certain degree of stretching. When LM is used in microwave devices and paired with elastic linings such as polydimethylsiloxane (PDMS), the shape and size of the devices can be changed according to actual needs to meet the requirements of flexibility and a multistate frequency band. In this work, we discuss the material properties, fabrication and functionalities of LM.

Dynamic Response of a Heat Damaged Fiber-Resin Beam Subjected to Harmonic Forcing at the Tip

2000 ◽  
Author(s):  
H. Nayeb-Hashemi ◽  
A. Harrison
Keyword(s):  
Dynamic Response ◽  
Material Properties ◽  
Resin Composite ◽  
Dominant Frequency ◽  
System Model ◽  
Diagnostic Process ◽  
Finite Element Models ◽  
Frictional Damping ◽  
Stiffness And Damping ◽  
Local Stiffness

Abstract A cantilever beam built of fiber-resin composite material and damaged by heat is evaluated for its dynamic response using numerical methods. The goal of research is to produce a diagnostic process in which dynamic response can be used to estimate the severity of damage to the beam. Research proceeds from formulation of the continuous media equations for vibration in a multiply segmented beam, to the development of finite element models for the beam. It is discovered that the results of these two methods are qualitatively different from the predictions of a lumped system model, in that the lumped system predicts that frictional damping should reduce the dominant frequency of vibration while the more elaborated models indicate that damping may increase the dominant frequency. It is further discovered that the size and location of damage (the geometry) are equally as important as the local stiffness and damping of the damaged region (the material properties). The results indicate that the dominant frequency of dynamic response is not a sufficient symptom for complete diagnosis of damage in the beam.

Identification of Nonlinear Property of Honeycomb Paperboard through Use of Hilbert Transform

2012 ◽  
Vol 590 ◽  
pp. 536-539
Author(s):  
Xiao Qin Wei ◽  
Da Peng Zhu
Keyword(s):  
Hilbert Transform ◽  
Nonlinear Property ◽  
Motion Equation ◽  
Damping Properties ◽  
Experiment Data ◽  
Free Response ◽  
Experiment System ◽  
Set Up ◽  
Stiffness And Damping

A method is formulated to model the properties of honeycomb paperboard based on Hilbert transform, In this method, there are no assumptions on the forms of the stiffness and damping properties, this method is truly nonparametric. An experiment system is set up to record the free response of the mass loaded honeycomb paperboard system, the experiment data are used to identify the stiffness and damping properties of honeycomb paperboard. The motion equation of mass loaded honeycomb paperboard system is formulated, the transmissibility curve is simulated, the comparison of the simulated curves and the experiment data indicates the model in this paper is accurate.

A New Device for Measuring the Viscoelastic Properties of Hydrated Matrix Gels

2002 ◽  
Vol 124 (2) ◽  
pp. 145-154 ◽  
Author(s):  
Jeffrey W. Parsons ◽  
Robin N. Coger
Keyword(s):  
Material Properties ◽  
Viscoelastic Properties ◽  
Type I Collagen ◽  
Bulk Material ◽  
Type I ◽  
New Device ◽  
Storage And Loss Moduli ◽  
Order Of Magnitude ◽  
Stiffness And Damping ◽  
Surrounding Fluid

Determinations of the viscoelastic properties of extracellular matrices (ECMs) are becoming increasingly important for accurate predictive modeling of biological systems. Since the interactions of the cells with the ECM and surrounding fluid (e.g., blood, media) each affect cell behavior; it is advantageous to evaluate the ECM’s material properties in the presence of the hydrating fluid. Conventional rheometry methods evaluate the bulk material properties of gel materials while displacing the hydrating liquid film. Such systems are therefore nonideal for testing materials such as ECMs, whose properties change with dehydration. The new, patent pending, piezoelectrically actuated linear rheometer is designed to eliminate this problem. It uses a single cantilever to apply an oscillating load to the gel and to sense the gel’s deflection. Composed of two thin film piezopolymer layers, the cantilever uses one layer as the actuator, and the second piezopolymer layer to measure the lateral movement of its attached probe. The viscoelastic nature of the ECM adds stiffness and damping to the system, resulting in the attenuation and phase shift of the sensor’s output voltage. From these parameters, the ECM’s shear storage and loss moduli are then determined. Initial tests on the BioMatrix I and type I collagen ECMs reveal that the first prototype of the piezoelectrically actuated linear rheometer is capable of accurately determining the trend and order of magnitude of an ECM’s viscoelastic properties. In this paper, details of the rheometer’s design and operating principles are described.

scholarly journals Experimental and numerical investigation on the components of a pantograph slider suspension

2019 ◽  
Vol 252 ◽  
pp. 05003
Author(s):  
Paweł Zdziebko ◽  
Adam Martowicz ◽  
Tadeusz Uhl
Keyword(s):  
Numerical Model ◽  
Material Properties ◽  
Model Building ◽  
Young Modulus ◽  
Experimental Procedure ◽  
Proper Material ◽  
Stiffness And Damping ◽  
Python Programming ◽  
Damping Model

Mechanical properties of the components of a pantograph’s slider suspension system have large influence on the quality of pantograph-catenary interaction. In the paper the authors present the results of their experimental research on the springs that are used in the pantograph being currently in operation in Europe. Static and dynamic tests were performed, which were aimed at determining the stiffness and damping coefficients respectively. Subsequently, the procedure for automated numerical model building for the pantograph’s springs was prepared employing the Python programming language and the MSC Marc solver. When a spring model is build (accordingly to the geometric properties of the springs used in tests), the elaborated algorithm iteratively tunes the material properties and computes static and dynamic load-cases, making direct reference to the experimental procedure. After completing several iterations the numerical model is finally validated, and proper material properties, as the Young modulus and the coefficients of Rayleigh damping model, are found. Then, the obtained model can be used to determine the damping and stiffness coefficients for springs characterizing various diameters, wire diameters, numbers of turns, etc. The presented modelling tool is useful for determining the pantograph sliders suspension characteristics.

scholarly journals An Experimental Technique for the Evaluation of Strain Dependent Material Properties of Hard Coatings

2008 ◽  
Vol 15 (6) ◽  
pp. 697-712 ◽  
Author(s):  
Shad A. Reed ◽  
Anthony N. Palazotto ◽  
William P. Baker
Keyword(s):  
Hard Coatings ◽  
Surface Measurement ◽  
Magnesium Aluminate ◽  
Laser Vibrometer ◽  
Minimal Amount ◽  
Magnesium Aluminate Spinel ◽  
Damping Properties ◽  
Electromagnetic Excitation ◽  
Stiffness And Damping ◽  
Strain Dependent

A novel vibration experiment consisting of a free-free boundary condition, an electromagnetic excitation source, a vacuum chamber, and a laser vibrometer based surface measurement system has been developed that permits high levels of excitation on highly damped specimens with a minimal amount of unwanted systematic error. While some of the aspects of this experiment are not unique, when combined with a processing technique that accounts for the nonlinearities present in the system, this experiment permits, accurate measurement of strain dependent stiffness and damping properties of hard coatings at high strain levels. This procedure has been demonstrated using a titanium beam that has been coated with a free-layer damping treatment of Magnesium Aluminate Spinel. The results indicate that Magnesium Aluminate Spinel has both nonlinear stiffness and damping properties. The stiffness asymptotes to a minimum value around 650 microstrain while the damping is a maximum around 100 microstrain. Additionally, the data contained herein cover a larger strain range for this material than previously reported.

Grain boundary segregation in metals

1992 ◽  
Vol 50 (2) ◽  
pp. 1204-1205
Author(s):  
C.L. Briant
Keyword(s):  
Fracture Surface ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Material Properties ◽  
Electron Spectroscopy ◽  
High Vacuum ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Local Concentration ◽  
The One

Grain boundary segregation is the process by which solute elements in a material diffuse to the grain boundaries, become trapped there, and increase their local concentration at the boundary over that in the bulk. As a result of this process this local concentration of the segregant at the grain boundary can be many orders of magnitude greater than the bulk concentration of the segregant. The importance of this problem lies in the fact that grain boundary segregation can affect many material properties such as fracture, corrosion, and grain growth.One of the best ways to study grain boundary segregation is with Auger electron spectroscopy. This spectroscopy is an extremely surface sensitive technique. When it is used to study grain boundary segregation the sample must first be fractured intergranularly in the high vacuum spectrometer. This fracture surface is then the one that is analyzed. The development of scanning Auger spectrometers have allowed researchers to first image the fracture surface that is created and then to perform analyses on individual grain boundaries.

Microstructural characterization of sol-gel coating on PET films

1994 ◽  
Vol 52 ◽  
pp. 886-887
Author(s):  
R. T. Chen ◽  
R.A. Norwood
Keyword(s):  
Ion Beam ◽  
Sol Gel ◽  
Industrial Applications ◽  
Hard Coatings ◽  
Nanometer Scale ◽  
Ion Beam Sputtering ◽  
Process Technology ◽  
Refractive Index Measurement ◽  
Organically Modified ◽  
Pet Films

Sol-gel processing has been used to control the structure of a material on a nanometer scale in preparing advanced ceramics and glasses. Film coating using the sol-gel process was also found to be a viable process technology in applications such as optical, porous, antireflection and hard coatings. In this study, organically modified silicate (Ormosil) coatings are applied to PET films for various industrial applications. Sol-gel materials are known to exhibit nanometer scale structures which havepreviously been characterized by small-angle X-ray scattering (SAXS), neutron scattering and light scattering. Imaging of the ultrafine sol-gel structures has also been performed using an ultrahigh resolution replica/TEM technique. The objective of this study was to evaluate the ultrafine structures inthe sol gel coatings using a direct imaging technique: atomic force microscopy (AFM). In addition, correlation of microstructures with processing parameters, coating density and other physical properties will be discussed.The materials evaluated are organically modified silicate coatings on PET film substrates. Refractive index measurement by the prism coupling method was used to assess density of the sol-gel coating.AFM imaging was performed on a Nanoscope III AFM (by Digital Instruments) using constant force mode. Solgel coating samples coated with a thin layer of Ft (by ion beam sputtering) were also examined by STM in order to confirm the structures observed in the contact type AFM. In addition, to compare the previous results, sol-gel powder samples were also prepared by ultrasonication followed by Pt/Au shadowing and examined using a JEOL 100CX TEM.

Relationships Between Grain Boundary Structure and Material Properties

1980 ◽  
Vol 38 ◽  
pp. 366-369
Author(s):  
Brian Ralph ◽  
Barlow Claire ◽  
Nicola Ecob
Keyword(s):  
Grain Boundary ◽  
Material Properties ◽  
Main Property ◽  
Grain Structure ◽  
Boundary Structure ◽  
Grain Boundary Structure ◽  
Property Changes

This brief review seeks to summarize some of the main property changes which may be induced by altering the grain structure of materials. Where appropriate an interpretation is given of these changes in terms of current theories of grain boundary structure, and some examples from current studies are presented at the end of this paper.

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