scholarly journals Overview on Determination of Elastic and Damping Properties of Different Materials using Impulse Excitation Technique

2018 ◽  
Vol 3 (3) ◽  
pp. 35-41 ◽  
Author(s):  
Inês Pereira
Keyword(s):  
Shear Modulus ◽  
Elastic Properties ◽  
Damping Properties ◽  
Analysis And Design ◽  
Dynamic Technique ◽  
Impulse Excitation ◽  
Different Types ◽  
Properties Of Materials ◽  
Dynamic Elastic Properties

Knowledge of elastic and damping properties of materials is very relevant for the analysis and design of components, as they are relevant parameters in the performance of structural materials. The impulse excitation technique is a renowned dynamic technique for measuring dynamic elastic properties as Young´s modulus, shear modulus and Poisson’s ratio, as well as damping properties. This paper provides a review on the applicability of the impulse excitation technique in the analysis of elastic and damping properties of different types of materials.

scholarly journals Enhancement of a New Methodology Based on the Impulse Excitation Technique for the Nondestructive Determination of Local Material Properties in Composite Laminates

2020 ◽  
Vol 11 (1) ◽  
pp. 101
Author(s):  
Carlo Boursier Niutta
Keyword(s):  
Resonant Frequency ◽  
Elastic Properties ◽  
Composite Laminates ◽  
Concentrated Mass ◽  
Modal Shape ◽  
Nondestructive Determination ◽  
Material Orientation ◽  
Impulse Excitation ◽  
Clamping System

A new approach for the nondestructive determination of the elastic properties of composite laminates is presented. The approach represents an improvement of a recently published experimental methodology based on the Impulse Excitation Technique, which allows nondestructively assessing local elastic properties of composite laminates by isolating a region of interest through a proper clamping system. Different measures of the first resonant frequency are obtained by rotating the clamping system with respect to the material orientation. Here, in order to increase the robustness of the inverse problem, which determines the elastic properties from the measured resonant frequencies, information related to the modal shape is retained by considering the effect of an additional concentrated mass on the first resonant frequency. According to the modal shape and the position of the mass, different values of the first resonant frequency are obtained. Here, two positions of the additional mass, i.e., two values of the resonant frequency in addition to the unloaded frequency value, are considered for each material orientation. A Rayleigh–Ritz formulation based on higher order theory is adopted to compute the first resonant frequency of the clamped plate with concentrated mass. The elastic properties are finally determined through an optimization problem that minimizes the discrepancy on the frequency reference values. The proposed approach is validated on several materials taken from the literature. Finally, advantages and possible limitations are discussed.

Vibration of Thick Circular Plate--Determination of Elastic Properties Through the Resonant Behaviour

1983 ◽  
Vol 7 (2) ◽  
pp. 58-64
Author(s):  
P. Priolo ◽  
C. Sitzia
Keyword(s):  
Finite Elements ◽  
Elastic Properties ◽  
Thick Plate ◽  
Plate Theory ◽  
Resonant Condition ◽  
High Frequencies ◽  
Thick Circular Plate ◽  
Properties Of Materials ◽  
Points Of View

The authors examine, from two complementary points of view, the main problem deriving from the necessity of deducing elastic properties of materials by considering the resonant condition of transversely vibrating discs, that is the determination of the efficiency at high frequencies of finite elements formulated with the assumptions of the thick plate theory. The first approach consists, having standardized the basic relations for various thick annular semi-analytical finite elements, in testing convergence and correspondence to known analytical solutions. The second consists in the experimental evaluation of the influence of thickness in deducing the Young’s modulus of a series of polycarbonate resin discs at frequencies corresponding to modes with up to eight nodal circles.

Study of the Mechanical Properties of Single-Walled Carbon Nanotubes

2008 ◽  
Author(s):  
Paola Jaramillo ◽  
Haym Benaroya
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Finite Element ◽  
Elastic Properties ◽  
Single Walled Carbon Nanotubes ◽  
Computational Time ◽  
Single Walled Carbon ◽  
Different Types ◽  
Properties Of Materials ◽  
Walled Carbon Nanotubes

Carbon nanotubes are composed of C-C covalent bonds, which are the strongest bonds found in nature. Hence, carbon nanotubes are identified as the “ultimate fiber” due to their great strength in the direction of the nanotube axis and their ability to enhance the elastic properties of materials. The first indications of synthesizing carbon nanotubes date back to 1952. Russian scientists Radushkevich and Lukyanovich [1] were able to produce nanosized hollow carbon filaments. Nevertheless, it was until 1991 that multi-walled carbon nanotubes (MWCNTs) were discovered by Sumio lijima [2, 3] at NEC Corporation Lab, which was followed by his study and synthesis of single-walled carbon nanotubes (SWCNTs) in 1993. Since their discovery, there has been a constant pursuit to understand the properties and identify the optimal applications of these structures. The paper focuses on the importance of carbon nanotubes and their ability to enhance the mechanical properties of other materials due to their unique elastic properties. Additionally, carbon nanotubes can improve the capabilities and properties of other materials, like polymer composite. Currently, there is an ongoing process to accurately understand the fundamental characteristics of these structures, in particular, to develop the governing laws necessary to control, predict, and manipulate these properties. This will eventually have an impact on the bulk properties of materials where carbon nanotubes may be incorporated. The current research focuses on the ability to create simplified models that can accurately predict the response of carbon nanotube structures undergoing different types of loading conditions. In this way, the mechanical characteristics regarding single-walled carbon nanotubes (SWCNTs) through finite element modeling are computed. A simplified finite element model is created in ANSYS for different types of SWCNTs with varying input parameters. An input array for the elastic modulus and load is generated to control the physical effects of these parameters in the nanotube structure. The geometries of the nanotubes are altered through various thicknesses employed for the construction of the C–C bonds. The current work contributes to the generation of different model responses to monitor the stress distribution employing a wide range of parameter values. The ability to introduce variability in the parameters and boundary conditions without altering the capabilities and computational time in the model represents the main contribution of this work.

Experimental study of parameters influencing the damping of particulate, fibre-reinforced, hybrid, and sandwich composites

2020 ◽  
Vol 111 (8) ◽  
pp. 688-697
Author(s):  
Zuzana Murčinková ◽  
Jozef Živčák ◽  
Jozef Zajac
Keyword(s):  
Composite Materials ◽  
Volume Fraction ◽  
Damping Ratio ◽  
Logarithmic Decrement ◽  
Sandwich Composites ◽  
Damping Properties ◽  
Different Types ◽  
Typical Time ◽  
Half Power

Abstract In this study, we focus on the experimental determination of damping expressed by logarithmic decrement, damping ratio, and loss factor of particulate, continuous- and discontinuous- fibre reinforced, hybrid, and sandwich composites using the free vibration decay effect evaluated using the logarithmic decrement and half-power bandwidth methods. Composite materials with damping properties of magnitude several orders higher than that of traditional engineering materials are well known. However, in one study, we present different types of composite materials with different damping properties depending on various parameters such as ply angle, volume fraction, material configuration, reinforcement geometry, temperature, etc., which provide varied options to design the material arrangement of dynamically loaded components to maximize damping. Moreover, in this study, we determine typical time and frequency domain curves for individual types of analysed composites.

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