On the understanding of damping capacity in SMA: From the material thermomechanical behaviour to the structure response

2020 ◽  
pp. 1045389X2097445
Author(s):  
Guillaume Helbert ◽  
Aleksandr Volkov ◽  
Margarita Evard ◽  
Lamine Dieng ◽  
Shabnam Arbab Chirani
Keyword(s):  
Damping Ratio ◽  
Standard Procedure ◽  
Vibration Signal ◽  
Damping Capacity ◽  
Phase Boundaries ◽  
Beam Structure ◽  
Structure Response ◽  
Thermomechanical Behaviour ◽  
Objective Reference

Superelastic Shape Memory Alloys (SMAs) provide a high damping capacity due to the hysteretic motion of the inter-phase boundaries during the martensitic transformation. They have demonstrated their ability to control vibrations of SMA-based Civil Engineering and Aerospace structures. In order to improve existing damping devices, characterization of SMA damping capacity is necessary, despite the lack of a standard procedure. Classical characterizations such as tensile or torsion tests on SMA samples are very attractive, the fact that they are common and simple to process. Furthermore, environment and loading conditions are quite easy to control. Different energy-based formulations have been proposed in the literature to explicitly predict SMA damping capacity from the hysteretic mechanical behaviour. The aim of this paper is to classify commonly used formulations from the literature, using a new thermomechanical vibration numerical model of a SMA beam structure. Thus, three energy-based predictions of SMA intrinsic damping ratio measured at the material scale are compared to the damping ratio measured from the free vibration signal at the SMA beam structure scale, taken as the objective reference. The formulation proposed by Piedbœuf and Gauvin provided a better match in three study-cases.

Inducing Frictional Force to Enhance the Transient Response in Beams

2019 ◽  
Vol 22 (2) ◽  
pp. 88-93
Author(s):  
Hamed Khanger Mina ◽  
Waleed K. Al-Ashtrai
Keyword(s):  
Numerical Analysis ◽  
Transient Response ◽  
Frictional Force ◽  
Damping Ratio ◽  
Experimental Results ◽  
Damping Capacity ◽  
Tightening Force ◽  
Contact Areas ◽  
Good Agreement ◽  
Ansys Workbench

This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.

scholarly journals Pedogenic characteristics of soil in Melur block, Madurai district, Tamil Nadu in India: A case study

2021 ◽  
Vol 13 (SI) ◽  
pp. 198-202
Author(s):  
P. Ramamoorthy ◽  
P. Christy Nirmala Mary
Keyword(s):  
Tamil Nadu ◽  
Human Life ◽  
Standard Procedure ◽  
Mapping Unit ◽  
Grid Sampling ◽  
Cadastral Maps ◽  
Sandy Clay ◽  
Site Characteristics ◽  
Wet Condition

Soil is an important source of human life and agricultural production. Studying on the pedon and its site characteristics pave the way for understanding the nature of soils and its utility. A study on pedological characterization of soils in Melur block, Madurai District (Tamil Nadu), was carried out during 2019-2020 using grid sampling with village map/cadastral maps. Soil mapping unit-based soil samples were collected in Chunampoor, Thuvarangulam, Poonjuthi and Veppapadupu and pedons were characterized as per the standard procedure. The results showed that soils were moderately deep to very deep in nature, ranging from 2.5 YR  3/6 to 10YR 4/6. The soil texture varied from sandy clay loam to sandy clay with weak to moderate sub-angular blocky structure. The consistency of soil varied from slightly hard to very hard when dry, very friable to firm when moist, slightly sticky to very sticky and slightly plastic to very plastic in wet condition. The crops viz., paddy, sugarcane, banana, groundnut and vegetables were very suitable for such type of soil of the Madurai district.

The Assessment of Material Characteristic Using Vibration Signal Analysis during Drilling Process

2014 ◽  
Vol 598 ◽  
pp. 3-7
Author(s):  
Othman Inayatullah ◽  
Faizal Hamid ◽  
Hew Wei Hon ◽  
Nordin Jamaludin ◽  
Shahrum Abdullah
Keyword(s):  
Signal Analysis ◽  
Maximum Amplitude ◽  
Vibration Signal ◽  
Damping Capacity ◽  
Drilling Process ◽  
Cnc Machine ◽  
Material Characteristic ◽  
Signal Parameters ◽  
Stainless Steel 304 ◽  
Vibration Signal Analysis

The purpose of this paper is to assess the material characteristic by using vibration signal analysis during drilling process. Generally, material with high mechanical properties exhibits low damping capacity and vice versa. The main objective of this paper is to develop a relationship between the signal parameters and the strengths of materials. Aluminum alloy 1100, stainless steel 304, and mild steel were selected as the specimens to be drilled using CNC machine. The vibration signal was captured using a transducer and recorded using a DAQ system. The signal parameters such as maximum amplitude, vibration energy, and the RMS value were extracted using MATLAB software. From the results obtained, the graphs of signal parameters versus strength of each specimen are plotted to show their relationship. It was found that the signal parameters increased exponentially as the strengths of materials increased. Besides that, the vibration signal of the specimens are analysed and compared based on their mechanical characteristics.

Experimental Investigation of Dynamics of Assembly with Typical Mechanical Joint

2016 ◽  
Vol 693 ◽  
pp. 324-331
Author(s):  
Xin Liu ◽  
Bei Bei Sun ◽  
Jian Dong Chen ◽  
Fei Xue ◽  
Ren Qiang Jiao
Keyword(s):  
Dynamic Stiffness ◽  
Damping Ratio ◽  
Bolted Joints ◽  
Damping Capacity ◽  
Bolted Joint ◽  
Vibration Data ◽  
Mechanical Joints ◽  
Vibration Behavior ◽  
Frictional Damping ◽  
Reference Specimens

Mechanical joints have a significant influence on the dynamics of assembled structure due to its discontinuity, uncertainty, frictional contact and micro-slip along the interface. To study the effect of mechanical interface on vibration behavior of industrial product, it is necessary to capture vibration data and investigate modal properties. In order to study effects of typical mechanical joints, double plates coupled with bolted joint are manufactured. Corresponding welded specimen was also manufactured for comparison and reference. Specimens were suspended by two flexible nylon cords for a free–free boundary condition and series of modal tests were carried out. Experimental results reveal that the preload in bolted joint affects the vibration behavior of assembly greatly, and the dynamic stiffness and natural frequency could be enhanced by increasing preload values of specimen. Bolted joints give rise to more frictional damping capacity within lower preload range in this test and welded specimen shows up much higher frequency and similar damping ratio.

scholarly journals Study on the Measurement Method of the Crack Local Flexibility of the Beam Structure

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Yumin He ◽  
Siyu Guo ◽  
Xiaolong Zhang
Keyword(s):  
Natural Frequency ◽  
Cross Sections ◽  
Measurement Method ◽  
Vibration Signal ◽  
Beam Structure ◽  
Crack Location ◽  
Influence Curves ◽  
Damage Degree ◽  
Local Flexibility ◽  
Sample Points

The crack which appears in the structure can be described by a local flexibility. With the occurrence and propagation of crack, the local flexibility will change. The change can effectively reflect the damage degree of the structure. In this paper, the measurement method of the crack local flexibility of the beam structure is presented. Firstly, a series of sample points are selected at the crack location and the possible value range of the crack local flexibility, and then these sample points are used as input parameters for the dynamic analysis of the beam structure. The vibration equation of beam structure is solved, and the frequency influence surface is drawn. In addition, the vibration signal of the beam is tested, and the first three order natural frequencies can be obtained. Thirdly, these frequencies measured are adopted to cut the natural frequency influence surfaces, and then the first three order natural frequency influence curves are drawn. The intersection points of these frequencies influence curves can indicate the crack local flexibility and the corresponding crack location. This method is suitable for measuring the local flexibility of crack with different shapes and types in the beam structure which have various cross sections.

scholarly journals Mechanical characterization of the AISI 316L alloy exposed to boriding process

DYNA ◽  
2020 ◽  
Vol 87 (213) ◽  
pp. 34-41 ◽  
Author(s):  
Ricardo Andrés García-León ◽  
Jose Martinez-Trinidad ◽  
Ivan Campos-Silva ◽  
Wilbert Wong-Angel
Keyword(s):  
Sliding Wear ◽  
Standard Procedure ◽  
Indentation Test ◽  
Boride Layer ◽  
Aisi 316L ◽  
Low Carbon ◽  
X Ray Diffraction ◽  
Boriding Process ◽  
Wear Tests

In this study, the powder-pack boriding process on low-carbon stainless steel was carried out at 1273 K for 4 h of exposure to obtain a layer around ~57 μm conformed by FeB, Fe2B, and others alloying elements. Firstly, the presence of iron borides formed on the surface of borided AISI 316L alloy was confirmed by optical microscopy combined with the X-ray diffraction analysis. After, the sensed Vickers indentation test was performed on the iron boride layer to estimate the behavior of hardness and Young’s modulus. Sliding wear tests on the borided AISI 316L alloy were performed according to the ASTM G133-05 standard procedure, with the following conditions: distances of 50 and 150 m, normal loads of 5 and 20 N, and a sliding speed of 30 mm/s. Finally, the results showed that the presence of FeB-Fe2B improves the resistance to wear around 41 times compared to the untreated material.

scholarly journals Dynamic Properties of Clean Sand Modified with Granulated Rubber

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Dervis Volkan Okur ◽  
Seyfettin Umut Umu
Keyword(s):  
Shear Modulus ◽  
Dynamic Characteristics ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Relative Size ◽  
Cyclic Behavior ◽  
Damping Capacity ◽  
Resonant Column ◽  
Strain Dependent

Waste automobile tires are used as additives or replacements instead of traditional materials in civil engineering works. In geotechnical engineering, tires are shredded to certain sizes and mixed with soil, especially used as backfill material behind retaining walls or fill material for roadway embankments. Compared to soil, rubber has high damping capacity and low shear modulus. Therefore, it requires the determination of the dynamic characteristics of rubber/soil mixtures. In this paper, the cyclic behavior of recycled tire rubber and clean sand was studied, considering the effects of the amount and particle size of the rubber and confining stresses. A total of 40 stress-controlled tests were performed on an integrated resonant column and dynamic torsional shear system. The effects of the relative size and proportion of the rubber on the dynamic characteristics of the mixtures are discussed. The dynamic properties, such as the maximum shear modulus, strain-dependent shear modulus, and damping ratio, are examined. For practical purposes, simple empirical relationships were formulated to estimate the maximum shear modulus and the damping ratio. The change in the shear modulus and damping ratio with respect to shear strain with 5% of rubber within the mixture was found to be close to the behavior of clean sand.

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