Analysis of Vibration Diagnostic Methods of Metal Structures

2021 ◽  
pp. 16-23
Author(s):  
T.A. Pautova
Keyword(s):  
Residual Life ◽  
Dynamic Structure ◽  
Metal Structure ◽  
Crack Size ◽  
Diagnostic Methods ◽  
Element Analysis ◽  
Vibration Diagnostics ◽  
Metal Structures ◽  
Crack Location ◽  
Vibration Parameters

Due to the constant machine complexity increasing as well as the requirements imposed on them, the issue of ensuring their reliability is becoming more and more urgent. The main part of any machine is supporting metal structure, which state determines the state of the machine as a whole. This determines the need to diagnose structures in order to prevent failures. At present, the methods of vibration diagnostics are being widely developed, as applied to objects of various industries. Scientists’ research is aimed at studying various types of defects, vibration parameters, methods for detecting defects and assessing the residual life. The article considers the main current trends in the development of vibration diagnostics methods. The sensitivity of the dynamic structure characteristics to the presence of a defect in the form of a crack has been investigated. A finite element analysis of a steel I-beam was performed for various cases of its fixation and crack location. The dependence of the natural frequencies and amplitude-frequency characteristics of the beam on the crack size has been analyzed. It is found that the presence of a defect has the greatest effect on the frequency response of the beam.

scholarly journals Residual life estimation of structural beam using experimental and numerical modal analysis methods

2020 ◽  
Vol 4 (2) ◽  
pp. 135-146
Author(s):  
Ganda Anand Siva ◽  
Shinigam Ramakrishna
Keyword(s):  
Modal Analysis ◽  
Natural Frequencies ◽  
Residual Life ◽  
Crack Depth ◽  
Common Element ◽  
Cracked Beam ◽  
Element Analysis ◽  
Crack Location ◽  
Parametric Studies ◽  
Ship Propeller

A structural beam is a common element in many mechanical structures such as ship propeller shaft, crane boom, and air craft wings. In the present paper experimental and numerical modal analysis are carried out for estimating the damage detection, geometric location of the damage, severity of damage and residual life of structural beam to prevent unexpected failures of the mechanical structures. Experimental and numerical modal analysis results for healthy and cracked beam are compared for validation of numerical methodology used in the present paper. Experimental modal analysis is performed on both healthy and cracked beam with the help of impact hammer, acceleration sensor and FFT analyzer associated with EDM (Engineering Data Management) software. Modal tests are conducted using impact method on selected locations of the entire healthy and cracked beam to find the first three natural frequencies, which are used to detect the presence of damage and geometric location of the damage. Three parametric studies are carried out to know the effect of crack depth, crack location and crack orientation on the natural frequencies of the cracked beam. Finally,  residual life of a healthy and cracked beam was estimated using Basiquin’s equation and finite element analysis software called ANSYS 18.1.

VIBRATION DIAGNOSTIC OF A FRICTION PROCESS IN SLIDE BEARINGS

Tribologia ◽  
2018 ◽  
Vol 278 (2) ◽  
pp. 73-80
Author(s):  
Dariusz LEPIARCZYK ◽  
Wacław GAWĘDZKI
Keyword(s):  
Measurement Data ◽  
Technical Condition ◽  
Diagnostic Methods ◽  
Diagnostic Systems ◽  
Vibration Displacement ◽  
Vibration Diagnostics ◽  
Slide Bearing ◽  
Bearing Sleeve ◽  
Vibration Parameters ◽  
Thermal Phenomena

An analysis of the condition of technical objects is carried out by diagnostic systems, the purpose of which is to detect irregularities in their operation and to prevent damages. In slide bearings, it applies to the diagnostic of friction and thermal phenomena of mating friction pairs. Among many methods of bearing diagnostics, special attention should be paid to vibration diagnostic methods based on measurements of relative vibration parameters or on absolute vibration (displacement, velocity, or acceleration of vibration). Methods of the vibration diagnostic of bearings rely on periodic or continuous measurements of relative vibration parameters of the bearing housing in relation to the rotor (in the case of slide bearings the measurements of the bearing sleeve in relation to the shaft neck) or absolute vibration parameters of the bearing housing (i.e. the sleeve in the case of slide bearing). The article presents a method of vibration diagnostics of friction phenomena that occur during the operation of slide bearings under various lubrication and load conditions. There are presented methods of analysis and the interpretation of measurement data obtained as a result of the conducted slide bearing tests on the laboratory stand. A method for assessing a technical condition of the slide bearing friction pairs is proposed.

scholarly journals Aircraft gas turbine engine vibration diagnostics

2017 ◽  
Vol 5 (4) ◽  
pp. 24 ◽  
Author(s):  
Stanislav Fábry ◽  
Marek Češkovič
Keyword(s):  
Soviet Union ◽  
Gas Turbine ◽  
Former Soviet Union ◽  
Health Indicators ◽  
Diagnostic Methods ◽  
Vibration Diagnostics ◽  
Turbine Engine ◽  
Vibration Sensors ◽  
Engine Vibration ◽  
Vibration Parameters

In the Czech and Slovak aviation are in service elderly aircrafts, usually produced in former Soviet Union. Their power units can be operated in more efficient way, in case of using additional diagnostic methods that allow evaluating their health. Vibration diagnostics is one of the methods indicating changes of rotational machine dynamics. Ground tests of aircraft gas turbine engines allow vibration recording and analysis. Results contribute to airworthiness evaluation and making corrections, if needed. Vibration sensors distribution, signal recording and processing are introduced in a paper. Recorded and re-calculated vibration parameters are used in role of health indicators.

scholarly journals Effect of Epoxy Glass Fiber Reinforcement on Dynamic Characteristics of Sheet Metal Structure

2019 ◽  
Vol 8 (10) ◽  
pp. 2226-2230
Keyword(s):  
Glass Fiber ◽  
Sheet Metal ◽  
Dynamic Characteristics ◽  
Metal Structure ◽  
Element Analysis ◽  
Metal Structures ◽  
Industrial Structures ◽  
Glass Fiber Reinforcement ◽  
Structure Vibration ◽  
Metal Processing

Stamped sheets are widely used in automotive and industrial structures. Their stiffness and strength depends on various shapes in which they are stamped (trapezoidal, semi-circular). Epoxy glass fiber is widely used for replacing the actual components or by reinforcement. Reinforcement of this sheet metal structures with epoxy glass fiber will adhere its strength characteristics and also help in stiffing the structure. In order to use same shape of structure with high stiffness reinforcement of epoxy glass fiber can be used on that structure. Vibration of plates greatly depends upon various characteristics like aspect ratio, boundary condition and fiber orientation. The developed shape of structure after sheet metal processing and the thickness of the structure also contributes to its stiffness. Present study involves vibration analysis based on the geometry of the stamped sheets. Fixed – fixed boundary conditions are taking into the consideration, because Stamped sheets generally fails at fastened locations or welded locations. Modal analysis is performed to study dynamic characteristics of reinforced structures. In order to validate the experimental results Comparative analysis is carried out by using finite element analysis. Conclusions are drawn and suitable future scope is suggested

КОНСТРУКТИВНО-ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ ХВОСТО-ВИХ БАЛОК СІТЧАСТОГО ТИПУ З ПОЛІМЕРНИХ КОМПО-ЗИЦІЙНИХ МАТЕРІАЛІВ ВЕРТОЛЬОТІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

2020 ◽  
pp. 15-30
Author(s):  
А. Г. Гребеников ◽  
И. В. Малков ◽  
В. А. Урбанович ◽  
Н. И. Москаленко ◽  
Д. С. Колодийчик
Keyword(s):  
Finite Element ◽  
Strain State ◽  
Layer Structure ◽  
Metal Structure ◽  
Element Model ◽  
Stress Strain ◽  
Element Analysis ◽  
Mesh Structure ◽  
Stress Strain State ◽  
Mesh Structures

The analysis of the design and technological features of the tail boom (ТB) of a helicopter made of polymer composite materials (PCM) is carried out.Three structural and technological concepts are distinguished - semi-monocoque (reinforced metal structure), monocoque (three-layer structure) and mesh-type structure. The high weight and economic efficiency of mesh structures is shown, which allows them to be used in aerospace engineering. The physicomechanical characteristics of the network structures are estimated and their uniqueness is shown. The use of mesh structures can reduce the weight of the product by a factor of two or more.The stress-strain state (SSS) of the proposed tail boom design is determined. The analysis of methods for calculating the characteristics of the total SSS of conical mesh shells is carried out. The design of the tail boom is presented, the design diagram of the tail boom of the transport category rotorcraft is developed. A finite element model was created using the Siemens NX 7.5 system. The calculation of the stress-strain state (SSS) of the HC of the helicopter was carried out on the basis of the developed structural scheme using the Advanced Simulation module of the Siemens NX 7.5 system. The main zones of probable fatigue failure of tail booms are determined. Finite Element Analysis (FEA) provides a theoretical basis for design decisions.Shown is the effect of the type of technological process selected for the production of the tail boom on the strength of the HB structure. The stability of the characteristics of the PCM tail boom largely depends on the extent to which its design is suitable for the use of mechanized and automated production processes.A method for the manufacture of a helicopter tail boom from PCM by the automated winding method is proposed. A variant of computer modeling of the tail boom of a mesh structure made of PCM is shown.The automated winding technology can be recommended for implementation in the design of the composite tail boom of the Mi-2 and Mi-8 helicopters.

scholarly journals Determination of the region of the limiting states occurrence in RVS-20000 with the subsidence of the external bottom contour

2018 ◽  
Vol 239 ◽  
pp. 06002
Author(s):  
P.V. Chepur ◽  
A.A. Tarasenko ◽  
A.A. Gruchenkova
Keyword(s):  
Technical Condition ◽  
Element Analysis ◽  
Metal Structures ◽  
Software Complex ◽  
Managerial Decisions ◽  
The Finite Element Analysis ◽  
Steel Tank ◽  
Intrinsic Stiffness ◽  
Bottom Contour

The problem of the limiting states occurrence in the structures of a vertical steel tank is investigated in this work. To study the SSS of the metal structures of the object, the authors created a numerical model of the RVS-20000 tank in the ANSYS software complex. The model considers the maximum number of elements with their geometry and connections affecting the tank SSS under non-axisymmetric loading, including beyond the elasticity of steel. Dependences between the parameters of intrinsic stiffness of the VST are obtained. The results of the finite element analysis made it possible to develop a technique for assessing the technical condition of the structure with the development of irregular subsidence of the external bottom contour. The proposed technique can be used by both operating and design organizations in making managerial decisions regarding the repair of RVS-20000 subjected to the base subsidence.

Nondestructive Detection of a Crack in a Triangular Cantilever Beam Based on Frequency Measurement

2007 ◽  
Vol 353-358 ◽  
pp. 2285-2288
Author(s):  
Fei Wang ◽  
Xue Zeng Zhao
Keyword(s):  
Cantilever Beam ◽  
Natural Frequencies ◽  
Frequency Measurement ◽  
Crack Size ◽  
Force Sensors ◽  
Rotational Spring ◽  
Cantilever Deflection ◽  
Crack Location ◽  
Small Force ◽  
Point Of Intersection

Triangular cantilevers are usually used as small force sensors in the transverse direction. Analyzing the effect of a crack on transverse vibration of a triangular cantilever will be of value to users and designers of cantilever deflection force sensors. We present a method for prediction of location and size of a crack in a triangular cantilever beam based on measurement of the natural frequencies in this paper. The crack is modeled as a rotational spring. The beam is treated as two triangular beams connected by a rotational spring at the crack location. Formulae for representing the relation between natural frequencies and the crack details are presented. To detect crack details from experiment results, the plots of the crack stiffness versus its location for any three natural modes can be obtained through the relation equation, and the point of intersection of the three curves gives the crack location. The crack size is then calculated using the relation between its stiffness and size. An example to demonstrate the validity and accuracy of the method is presented.

Determination of Critical Crack Size Utilizing a Fracture Mechanics Test in Equipment Under Fatigue

2009 ◽  
Author(s):  
Irene Garcia Garcia ◽  
Radoslav Stefanovic
Keyword(s):  
Heat Treatment ◽  
Fracture Mechanics ◽  
Crack Size ◽  
Operational Experience ◽  
Element Analysis ◽  
Critical Crack ◽  
Circumferential Welds ◽  
Fea Model ◽  
Critical Crack Size

Equipment that is exposed to severe operational pressure and thermal cycling, like coke drums, usually suffer fatigue. As a result, equipment of this sort develop defects such as cracking in the circumferential welds. Operating companies are faced with the challenges of deciding what is the best way to prevent these defects, as well as determining how long they could operate if a defect is discovered. This paper discusses a methodology for fracture mechanics testing of coke drum welds, and calculations of the critical crack size. Representative samples are taken from production materials, and are welded employing production welding procedures. The material of construction is 1.25Cr-0.5Mo low alloy steel conforming to ASME SA-387 Gr 11 Class 2 in the normalized and tempered condition (N&T). Samples from three welding procedures (WPS) are tested: one for production, one for a repair with heat treatment, and one for repair without heat treatment. The position and orientation of test specimen are chosen based on previous surveys and operational experience on similar vessels that exhibited cracks during service. Fracture mechanics toughness testing is performed. Crack finite element analysis (FEA) model is used to determine the path-independed JI-integral driving force. Methodology for the determination of critical crack size is developed.

Economical design for long-span soil – metal structures

1996 ◽  
Vol 23 (4) ◽  
pp. 838-849 ◽  
Author(s):  
Hesham Mohammed ◽  
John B. Kennedy
Keyword(s):  
Dimensional Analysis ◽  
Structural Engineering ◽  
Three Dimensional ◽  
Metal Structure ◽  
Reinforced Soil ◽  
Soil System ◽  
Metal Structures ◽  
Long Span ◽  
Economical Design ◽  
Soil Metal

Soil – metal structures consisting of metal conduits covered with soil have been used extensively for short-span bridges. Recently, some designers ventured into utilizing them for longer spans with shallow soil cover which has led to some failures. Long-span soil – metal structures are often designed with transverse stiffeners attached to the metal structure. Another approach is the use of a reinforced-soil system in which the surrounding soil is reinforced and the metal conduit is tied into the soil. In this paper, a three-dimensional analysis of long-span soil – metal structures is carried out using these two approaches. The analysis is verified and substantiated by results from laboratory models. The structural responses from the two designs show that the latter design approach leads to a more economical structure. A design example based on the Cheese Factory Bridge built in Ontario in 1984 is presented. Key words: bridges, design, long span, reinforced soil, soil – metal structures, structural engineering, three-dimensional analysis.

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