Vitalijs Pavelko

• Riga Technical University

The outcomes of standard test of a carbon/epoxy layered composite using DCB specimen for measuring of the I-mode interlaminar fracture toughness (IFT) were analysed. Using the test results and earlier developed the model of quasi-static growth of crack (delamination) in layered composite, the investigation of variable properties of IFT was continue...

The goal of this article is to solve problems of automated monitoring systems of industrial and aviation constructions. Based on the latest research results, the most cost-effective solutions are covered, and a practical solution is offered. This article is part of the scientific project “Development of an integrated sensor system for material and...

Using the model of quasi-static crack growth and test result of the double cantilever beam (DCB) sample of layred carbon/epoxy composite, the general regularities of the interlaminar crack resistance of mode 1 were studied. The main attention was focused on the variability of crack resistance associated, on the one hand, with the continuity of the...

The improved version of the theoretical model of quasi-static crack growth is presented here. Small-scale Dugdale-type cohesive zone of a crack is principal assumption and main restriction of proposed model. The nonlinear first-order differential equation describes the quasi-static process of crack growth. In dimensionless form this equation is inv...

Statistical analysis of CCD (correlation coefficient deviation) index for the structural damage detection by vibration-based method was performed. Statistic data set was collected in a full-scale test of a large aircraft component. After special pre-processing the most informative narrow frequency band was selected for obtaining the statistic set o...

The theoretical model of quasi-static crack growth in the elastic-plastic material under load variation in a wide range. Small-scale yielding is principal assumption and main restriction of proposed theory. The model of crack growth provides for continues and interrelated both the crack propagation and plastic deformation development. The nonlinear...

Nowadays the idea of the use of a construction monitoring system is no longer anything unheard or even new. The use of such systems is considered in the fields of Navy, Aviation, Oil industry, etc. Yet any of such system so far suffers from their rigidness, the sensory systems are limited by the construction material properties, sensory area covere...

Nowadays the idea of the use of a construction monitoring system is no longer anything unheard or even new. The use of such systems is considered in the fields of Navy, Aviation, Oil industry, etc. Yet any of such system so far suffers from their rigidness, the sensory systems are limited by the construction material properties, sensory area covere...

The goals of this article it to solve problems of automated monitoring systems for industrial constructions. Within this article several NDT systems are analysed, that have the potential to be used for automated monitoring system, covered their main pros and cons. Based on the latest research the most cost effective solutions are covered.

In this paper the effect of plasticity of an adhesive to interlaminar fracture toughness of adhesive bond of thin-walled layered composite is investigated. The characteristics of failure of low toughness adhesive layer were obtained using the double cantilever beam (DCB) sample. The main features of plasticity effect are obtained. The procedure of...

In the presented paper there are investigated the basic problems of the local system of SHM of large scale aircraft component. Vibration-based damage detection is accepted as a basic condition, and main attention focused to a low-cost solution that would be attractive for practice. The conditions of small damage detection in the full scale structur...

Several general effects of boundary conditions and their adequate description at structural dynamic computational simulation constitute the main subject of the discussion. First, an analytical model of elastically supported beam was considered to evaluate the effects of support compliance to the basic dynamic characteristics. Second, a more complex...

The aim of this study is estimation of the effect of large deflections of a double-cantilever beam (DCB) on the accuracy of determination of the mode I interlaminar fracture toughness GIc of layered composites by using the nonlinear theory of bending of beams. The differential equation of the deflection curve of arm of the DCB specimen in the natur...

Earlier the effect of fatigue crack opening/closing (FCOC) to ultrasound guided wave propagation was investigated. The purpose of this article is to evaluate this effect to the electromechanical impedance (EMI) of the system "piezoelectric transducer / host structure. Experimental study performed using the flat samples of aluminum alloy. One of the...

Earlier presented the geometrically nonlinear model of a flexible beam (cylindrical bending of a plate) was used for analysis of post-buckling behavior of the layered composite with delamination at compression. In this paper the model is used for more details nonlinear analysis of double cantilever beam (DCB) that used in standard test for determin...

1D nonlinear model of a thin plate (or beam) with delamination was developed earlier. Large deflections and membrane strains of a plate in buckled state, as well as the strain energy described using elliptic integrals. The Griffith-type energy condition was used as a criteria of delamination propagation. The analysis of the destruction of the plate...

Purpose - The purpose of this paper is to present the problems of the electromechanical impedance (EMI), especially its applications for structural health monitoring of aircraft bolt-joints and innovative approach of EMI prediction at loosening of bolt-joints. Design/methodology/approach - This experimental study includes the results of a full-scal...

The paper focuses on the further development of the model of the electromechanical impedance (EMI) of the piezoceramics transducer (PZT) and its application for aircraft structural health monitoring (SHM). There was obtained an expression of the electromechanical impedance common to any dimension of models (1D, 2D, 3D), and directly independent fro...

A revision of the basic assumptions those are usually used in the analysis of stability of thin delaminated layer and delamination propagation in a compressed composite is presented in this paper. For this purpose, the theory of flexible elastic plates with large displacements was used. As a result the compressive force and the total longitudinal s...

An accurate 1D model of post-buckling deformation of a thin sub-laminate of layered composite is develloped using nonlinead theory of slender plate. The strain energy realize rate at delamination propagation is obtained via the elliptical integrals. A model of fracture buckled sub-laminate is implemented and used for general analysis of progressive...

Some problems of the electromechanical impedance (EMI), especially its applications for structural health monitoring of aircraft bolt-joints and innovated approach of EMI prediction at loosening of bolt-joints are objectives of research. The full-scale test was performed using the Mi-8 helicopter tail beam. Effect of bolt-joint loosening was invest...

Based on mode selective monitoring of the transport of guided ultrasonic waves with high temporal resolution achieved by correlation techniques, a helicopter tail boom section, manufactured from aluminum, has been monitored concerning structural health and load including monitoring under shaker driven conditions. The characteristic sensitivities of...

The phenomenon of the Lamb wave interaction with fatigue crack in Al2024-T3 sheet was investigated at cyclic loading. Mentioned effect is associated with the crack open/close that change acoustic impedance of a crack. Analytical simulation of fatigue crack opening using the generalized Dugdale’s model of a crack in thin plate shows good accordance...

Contact strength of the GFRC was investigated theoretically and experimentally. The sizesof contact spot and indention of spherical and cylindrical body were defined by iterations repeating the procedure of finite element analysis. The use of the general and special criteria of destruction can give the sufficient information for the approximate pre...

The problems of experimental system of SHM are discussed in this article. The elements ofESHM system were designed and mounted in some zones structure and used far-field and near-field damage detection. As the objects of full-scale testing is used the helicopter MI-8 tail beamthat is typical example of Al alloy structure. The ultrasonic methods wer...

The basic purpose of given article is consideration of the problems connected with application of a method of concentrated weights in the tasks of mechanical systems dynamics at non-classic internal and external constraints. The method of the concentrated weights is convenient means of the analysis of dynamic properties of elastic mechanical system...

The results of analytical and experimental researches concerning predicting of fatigue crack growth in the operating conditions are presented. First of all the main factors causing a fatigue damage initiation and growth are analyzed and divided to two groups. Common conditions of fatigue damage precise predicting are established. The problem of fat...

Results of theoretical and experimental research of stresses in the skin of a tail beam of an Mi‐8 helicopter at resonant dynamic loading are discussed in this paper. It is shown that resonant tests of the object with an appropriate choice of configuration of internal and external constraints are one of the most effective and economical ways to ach...

The basic purpose of this article is consideration of the problems connected with the application of a method of concentrated weights in the tasks of mechanical system dynamics with non‐classic internal and external constraints. The method of concentrated weights is a convenient method to analyse the dynamic properties of elastic mechanical systems...

The establishment of reliable correlations between t he extend of damage and a sensor response using automated non destructive testing (structural health m onitoring) is the first aim of the present paper. The second and its main aim is the estimation of the efficiency of different approaches of the fatigue crack prediction when scalar parameters a...

The aim of this paper is the analysis of rod cross‐ply bending and stability of rod systems in the presence of cracks. The power concept (its theoretical base is Maxwell's theorem about the reciprocity of displacements) and linear fracture mechanics methods for research of mechanical properties of rod systems in the presence of cracks nave been use...

A model for a flat isolated layer of a unidirectional fibrous composite with a regular structure is constructed to investigate the possible variants of its failure development. An integrodifferential equation for determining the forces in fibers is obtained. Primary attention is focused on examining the failure process after the rupture of one fibe...

p. 207-209.

Тезисы докладов Международной НТК. - Москва: МТ РФ-МГТУ ГА, 1996. - С.83.

Рига: РАУ, 1996

Riga: RAU, 1996, pp.16-21.

-Москва: МГТУ ГА, 1996.

The article presents the results of investigations into the correlation between fatigue crack growth and parameters of acoustic emission. It suggests an analytical model of the correlation between fatigue crack growth and the total count of acoustic emission per cycle. On the basis of the formulated model and of the obtained experimental results a...

Data are presented on the conditions of a flight experiment aimed at the study of fracture toughness characteristics using crack growth indicators. Crack growth in a wing center section panel is considered as an example. Preliminary quantitative estimates of the parameters of a kinetic fracture diagram are obtained.

A procedure is described for studying residual deformations on the surface of a specimen or an article. Accuracy is evaluated and application bounds of the method for determination of residual deformations are determined. Strong heterogeneity in distribution of residual deformations induced by heterogeneity of the material structure is shown. Regul...

THE ARTICLE CONSIDERS A CHANGE IN THE FREQUENCY OF NATURAL VIBRATIONS OF A PART WITH THE APPEARANCE OF A CRACK.IT IS SHOWN THAT THE CHANGE CAN SERVE AS SOURCE MATERIAL ONLY WHEN ESTIMATING THE DIMENSIONS OF THE CRACK, OR FOR EXPERIMENTAL DETERMINATION OF THE COEFFICIENT OF STRESS INTENSITY.(A)

The ultrasonic detection of uniform corrosion in a thin sheet of aluminum alloy 2024-T3 was investigated at an early stage of corrosion damage. The artificial corrosion, similar to the corrosion in lap joints during operational service, was achieved using a corrosive solution as described in the literature. The corrosion damage intended was relativ...

The purpose of the present report consists in studying an opportunity of use of devices for registration of complex signals in thin- walled details of structures. Lamb's wave properties were used for explanation of dynamic reaction of thin plate surface when in some place there is some source of impulse loading. The experiment on the study of some...

Results of experimental studies of the fatigue life of a transverse riveted joint and a perforated plate are presented. The calculated values of the fatigue life of the riveted joint based on the applied theory of fatigue fracture are compared with experimental results. Problems associated with the estimation of accrued fatigue life prior to crack...

It has been shown in a previous study (Pavelko and Popov, 1988) that an analysis of the irreversible deformation of the free surface of a component or a structure near the edges of a growing crack can provide important information on the fracture toughness characteristic of the component material. Here, this approach is extended to the determinatio...

The purpose of the present report consists in studying an opportunity of use of devices for registration of complex signals in thin-walled details of structures. Lamb's wave properties were used for explanation of dynamic reaction of thin plate surface when in some place there is some source of impulse loading. The experiment on the study of some p...

The suppositions on AE conformity to phases of fatigue fracture development are made at the base of АE process formation self-similarity postulate and of one of microcrack system configuration stability at the polycrystalline material. The calculations under the offered model do not contradict experimental data obtained at the aluminum alloy.

Some completed model of the multi-site fatigue damage, constructed for a structure containing a series of the same type concentrators of stresses, located periodically along one straight line in more detail is considered. The model is constructed at the assumptions that the residual structural strength at presence of every possible damages uniquely...

Problems of the electromechanical impedance (EMI) method for structural health monitoring of aircraft are analyzed. The piezoceramics transducer EMI changes were investigated experimentally at the different kinds of artificial damages. The 1-D partial model of constrained PZT is developed and validated by special test. The some generalized model of...