Evgeny Petrov

University of Sussex · Department of Engineering and Design

A method for parametric analysis of the stability loss boundary has been developed for periodic regimes of nonlinear forced vibrations for a first time. The method allows parametric frequency-domain calculations of the stability loss together with the vibration amplitudes and design parameter values corresponding to the stability boundaries. The tr...

An efficient frequency-domain method has been developed to analyse the forced response of large-scale nonlinear gas-turbine structures with bifurcations. The method allows: detection and localization of the design and operating conditions sets where bifurcations occur; calculation of tangents to the solution trajectory and continuation of solutions...

A frequency-domain method has been developed to predict and comprehensively analyse the limit-cycle flutter-induced vibrations in bladed discs and other structures with nonlinear contact interfaces. The method allows direct calculation of the limit-cycle amplitudes and frequencies as functions of contact interface parameters using realistic large-s...

A highly accurate and computationally efficient method is proposed for reduced modeling of jointed structures in the frequency domain analysis of nonlinear steady-state forced response. The method has significant advantages comparing with the popular variety of mode synthesis methods or forced response matrix methods and can be easily implemented i...

An effective method for analysis of periodic forced response of nonlinear cyclically symmetric structures has been developed. The method allows multiharmonic forced response to be calculated for a whole bladed disc using a periodic sector model without any loss of accuracy in calculations and modelling. A rigorous proof of the validity of the reduc...

This paper develops an efficient method for calculations of stress levels, accumulation of high-cycle fatigue (HCF), and mistuning optimization aimed at the reduction of the fatigue damages for mistuned bladed disks under transient vibrations caused by variation of the rotation speed in the vicinity of resonance frequencies. The expressions for the...

This paper develops an efficient method for calculations of stress levels, accumulation of HCF and mistuning optimization aimed at the reduction of the fatigue damages for mistuned bladed disks under transient vibrations caused by variation of the rotation speed in the vicinity of resonance frequencies. The expressions for the sensitivities of the...

During accelerations and decelerations of gas-turbine engines, the transient vibration effects in bladed disk vibration become significant and the transient response needs to be efficiently and accurately assessed. This paper develops an effective method for efficient calculations of the sensitivity of the transient vibration response for a mistune...

During accelerations and decelerations of gas-turbine engines, the transient vibration effects in bladed disk vibration become significant and the transient response needs to be efficiently and accurately assessed. In this paper, an effective method is developed for efficient calculations of the sensitivity of the transient vibration response for a...

New numerical tools ContaDyn and InterDyn have been developed at University of Sussex for the analysis of nonlinear forced response for tuned and anisotropy mistuned bladed disks with friction contact interfaces. The tools offer capabilities for calculating the nonlinear forced response and its sensitivity with respect to the anisotropy orientation...

During fast gas-turbine engine acceleration and deceleration the transient vibration effects in bladed disk vibration become significant and the transient response has to be calculated. In this paper an effective method is developed for efficient calculations of the transient vibration response for mistuned bladed disks under varying rotation speed...

During fast gas-turbine engine acceleration and deceleration the transient vibration effects in bladed disk vibration become significant and the transient response has to be calculated. In this paper an effective method is developed for efficient calculations of the transient vibration response for mistuned bladed disks under varying rotation speed...

Gas turbine engines change the rotation speed during operation in a wide range from zero to the speed corresponding to the cruise flight and the history of the rotation speed variation is individual for each flight. During the engine operation the bladed disks pass different resonances frequencies and may experience significant vibration amplitudes...

A method is proposed to analyse the modal damping in mistuned bladed-disc with root joints using large finite element models and the detailed description of frictional interactions at contact interfaces. The influence of mistuning on the dissipated energy for different blades on a bladed-disc and the modal damping factors for different vibration le...

One of the major sources of the damping of the forced vibration for bladed disk structures is the micro-slip motion at the contact interfaces of blade-disk joints. In this paper, the modeling strategies of nonlinear contact interactions at blade roots are examined using high-fidelity modelling of bladed disk assemblies and the nonlinear contact int...

A method is proposed to analyse the modal damping in mistuned bladed-disc with root joints using large finite element models and the detailed description of frictional interactions at contact interfaces. The influence of mistuning on the dissipated energy for different blades on a bladed-disc and the modal damping factors for different vibration le...

An effective method is developed for the efficient calculation of the transient vibration response for mistuned bladed disks under complex excitation and varying rotation speeds. The method uses the large-scale finite element modelling of the bladed disks allowing the accurate description of the dynamic properties of the mistuned bladed disks. The...

A method for the analysis of amplitude-dependent modal damping factors is developed for the cases when the energy dissipation is caused by the micro-slip motion at friction contacts of blade root joints. The modal damping at root joints for a lone blade and for tuned bladed disc assemblies is studied. Large three-dimensional finite element models a...

High cycle failure of blades and vanes caused by the vibration is one of the major causes reducing the lifetime of turbomachines. For multiblade packets, the failure may occur at vibrations with high frequencies that can reach up to tens of kHz. The experimental modal testing of blades is crucial for the validation of numerical models and for the o...

Monocrystalline blades used in gas turbines exhibit material anisotropy, and the orientation of the anisotropy axis affects the deformation of the bladed disk. Considering the orientation of the anisotropy axis as a random design parameter, the uncertainty and sensitivity analysis for static blade deformations are presented for the first time. The...

In gas-turbine engines and other rotating machinery structures rubbing contact interactions can occur when the contacting components have large relative motion between components: such as in rotating bladed disc-casing rubbing contacts, rubbing in rotor bearing and labyrinth seals, etc. The analysis of vibrations of structures with rubbing contacts...

A new method has been developed for the analysis of nonlinear forced response of bladed disks mistuned by blade anisotropy scatter and for the forced response sensitivity to blade material anisotropy orientations. The approach allows for the calculation of bladed disks with nonlinear friction contact interfaces using the multi-harmonic balance meth...

In gas-turbine engines and other rotating machinery structures rubbing contact interactions can occur when the contacting components have large relative motion between components: such as in rotating bladed disc-casing rubbing contacts, rubbing in rotor bearing and labyrinth seals, etc. The analysis of vibrations of structures with rubbing contacts...

High-pressure turbines of modern gas-turbine engines use single crystal blades that exhibit material anisotropy. Due to manufacturing tolerances, each blade in the bladed disk will have different crystal anisotropy axis orientation, thereby creating mistuning in the structure. In this paper, the blade anisotropy angles are considered as uncertain d...

A new method has been developed for the analysis of nonlinear forced response of bladed disks mistuned by blade anisotropy scatter and for the forced response sensitivity to blade material anisotropy orientations. The approach allows for the calculation of bladed disks with nonlinear friction contact interfaces using the multi-harmonic balance meth...

An effective method is developed for efficient calculations of the sensitivity of the maximum forced response levels for mistuned bladed disks with respect to blade frequency mistuning. The expressions for 1st and 2nd order sensitivity coefficients are derived in an analytical form which provides high accuracy and computational efficiency. Then, th...

Several contact pairs were built on the contact surface to simulate the micro-slip at the blade root joint. Control variate method was employed to gain the hysteresis loop with friction force and relative displacements in two-dimensional blade root joints contact surface under steady vibration. Analysis and assessments were carried out for paramete...

The extreme value theory was used to analyze the statistical characteristics of maximum forced response of the mistuned bladed disks, and applied to a compressor disk. The mistuning bladed disk was reduced and modeled. The Monte Carlo method was used to simulate the response calculation, and the distribution characteristics for the amplification fa...

A methodology for the comprehensive frequencydomain analysis of stability of periodic vibration regimes of bladed discs with nonlinear contact interfaces is proposed. The methodology is aimed at using realistic finite models of bladed discs and other gas-turbine structures that can comprise very the large number of degrees of freedom. The methodolo...

A method is developed for the calculation of the sensitivities of modal characteristics and forced response of material anisotropy mistuned bladed disk with respect to crystal orientation using high-fidelity finite element models. An efficient approach using gradient based polynomial chaos is developed to obtain statistical characteristics for forc...

In machinery structures with joints, the contact pressures at contact interfaces are usually high enough to ensure that the contacting components stay joined and the gross slip does not occur. Nevertheless, the small relative slip over parts of the contact interface, i.e. the microslip, contributes significantly to the vibration damping. In the hig...

Single crystal blades used in high pressure turbine bladed disks of modern gas-turbine engines exhibit material anisotropy. In this paper the sensitivity analysis is performed to quantify the effects of blade material anisotropy orientation on deformation of a mistuned bladed disk under static centrifugal load. For a realistic, high fidelity model...

A new method has been developed for sensitivity calculations of modal characteristics of bladed disks made of anisotropic materials. The method allows the determination of the sensitivity of the natural frequencies and mode shapes of mistuned bladed disks with respect to anisotropy angles that define the crystal orientation of the monocrystalline b...

Single crystal blades used in high pressure turbine bladed disks of modern gas-turbine engines exhibit material anisotropy. In this paper the sensitivity analysis is performed to quantify the effects of blade material anisotropy orientation on deformation of a mistuned bladed disk under static centrifugal load. For a realistic, high fidelity model...

A new method has been developed for sensitivity calculations of modal characteristics of bladed disks made of anisotropic materials. The method allows the determination of the sensitivity of the natural frequencies and mode shapes of mistuned bladed disks with respect to anisotropy angles that define the crystal orientation of the monocrystalline b...

A method for parametric analysis of the stability loss boundary has been developed for periodic regimes of nonlinear forced vibrations for a first time. The method allows parametric frequency-domain calculations of the stability loss together with the vibration amplitudes and design parameter values corresponding to the stability boundaries. The tr...

In this paper, a methodology is developed for analysis of modal damping in root joints of bladed discs using large finite element models and detailed description of friction contacts at contact interfaces of the joints. The methods allows the analysis of: (i) a single blade vibration and (ii) a bladed-disc assembly for any family of modes (lower an...

The forced response of bladed discs is very sensitive to random blade mistuning. This paper proposes an effective sensitivity analysis method to explore the impact of blade mistuning parameters on the maximum vibrational amplitude of mistuned bladed discs. This method is constructed based on the reduced-order model and a subsequent forced response...

A novel approach to identify the crystal orientation of turbine blades with anisotropy materials is proposed. Based on enhanced mode basis, with the main advantages of its efficiency, accuracy and general applicability, the blade vibration mode of each order is linearly constructed by several specified mode shapes, which are obtained from the consi...

A new method is developed for the forced response analysis of mistuned bladed disks manufactured from anisotropic materials and mistuned by different orientations of material anisotropy axes. The method uses (i) sector finite element (FE) models of anisotropic bladed disks and (ii) FE models of single blades and allows the calculation of displaceme...

For the analysis of essentially nonlinear vibrations, it is very important not only to determine whether the considered vibration regime is stable or unstable but also which design parameters need to be changed to make the desired stability regime and how sensitive is the stability of a chosen design of a gas-turbine structure to variation of the d...

For the analysis of essentially nonlinear vibrations it is very important not only to determine whether the considered vibration regime is stable or unstable but also which design parameters need to be changed to make the desired stability regime and how sensitive is the stability of a chosen design of a gas-turbine structure to variation of the de...

In the turbo-machinery structures with joints the contact pressures at contact interfaces are usually high enough to ensure that the contacting components stay joined and the gross slip does not occur. Nevertheless, the small relative slip over parts of the contact interface, i.e. the micro-slip, contributes significantly to the vibration damping....

An efficient method is proposed for the multiharmonic frequency domain analysis of the stability for nonlinear periodic forced vibrations in gas-turbine engine structures and turbomachines with friction, gaps and other types of nonlinear contact interfaces. The method allows using large-scale finite element models for structural components together...

An efficient method is proposed for the multiharmonic frequency domain analysis of the stability for nonlinear periodic forced vibrations in gas-turbine engine structures and turbomachines with friction, gaps and other types of nonlinear contact interfaces. The method allows using large-scale finite element models for structural components together...

This paper proposes an effective method for sensitivity analysis of forced response of bladed discs to blade mistuning. The numerical studies of forced response of a turbine bladed disc vibrating in the frequency ranges corresponding to resonances with higher modes are also presented. The blade mistuning is modelled by specially defined mistuning m...

This paper is focused on the analysis of effects of mistuning on the forced response of gas-turbine engine bladed discs vibrating in the frequency ranges corresponding to higher modes. For high modes considered here the blade aerofoils are deformed during vibrations and the blade mode shapes differ significantly from beam mode shapes. A model reduc...

This paper is focused on the analysis of effects of mistuning on the forced response of gas-turbine bladed discs vibrating in the frequency ranges corresponding to higher modes. For high modes the blade aerofoils are deformed during vibrations and the blade mode shapes differ significantly from beam mode shapes. A model reduction technique is devel...

In this paper, the forced response of mistuned bladed disc is studied when excitation frequencies are high and high families of modes are excited. A model reduction technique is developed for the computationally efficient analysis of high-frequency forced response for bladed discs using high-fidelity finite element models. The finite element model...

An efficient frequency-domain method is developed to calculate the sensitivity of multiharmonic amplitudes of the limit-cycle oscillations and their primary frequency to variation of the nonlinear contact interface parameters and aerodynamic characteristics. The method allows highly accurate and fast determination of the sensitivity coefficients to...

An effective method has been developed to analyse the progressive loss of friction dampers due to friction-induced wear in tuned and mistuned bladed discs. The method allows the calculation of nonlinear forced response levels and schemes of the damper loss using large-scale finite element bladed disc models and detailed modelling of friction contac...

The finite element analysis of individual components of aircraft engine casings provides high accuracy and a good agreement with the measured response data. However, when these components are assembled, the accuracy of such predictions can significantly deteriorate since models describing stiffness and friction properties of joints are linearised....

A method has been developed for frequency domain analysis of steady state forced response in gas turbine engines in the presence of rubbing and snubbing contacts between bladed discs and casing and between other rotor and stator engine components. The multiharmonic contact interface elements have been derived for modelling the nonlinear contact int...

A new effective method for comprehensive modelling of gas flow effects on vibration of nonlinear vibration of bladed discs has been developed for a case when effect of the gas flow on the mode shapes is significant. The method separates completely the structural dynamics calculations from the significantly more computationally expensive computation...

The modelling of nonlinear friction contact interfaces in structural dynamics currently attracts large research interest since the accurate characteristics of the friction interfaces are required in the nonlinear dynamic analysis of assembled structures. For an accurate representation of friction contact interfaces it is important to ensure that a...

The design of high cycle fatigue resistant bladed disks requires the ability to predict the expected damping of the structure in order to evaluate the dynamic behavior and ensure structural integrity. Highly sophisticated software codes are available today for this nonlinear analysis, but their correct use requires a good understanding of the corre...

The newly revealed phenomenon of reduction of forced response levels in a mistuned bladed disk to levels significantly (e. g., by a factor of 2 and more) lower than that of its tuned counterpart is studied in detail on an example of a realistic bladed disk. Statistical properties of the amplification factor of the mistuned forced response calculate...

A methodology is developed for analysis and the global optimization of resonance peak forced response levels and frequencies. Essentially nonlinear vibrations of gas-turbine structures with friction and gap contact interfaces are considered. The methods developed allow effective analysis for large-scale finite element models containing millions of...

A methodology has been developed to analyse and to optimize the resonance peak amplitudes and frequencies for essentially nonlinear periodic vibrations of jointed structures. The frequency domain analysis of realistic finite element models of jointed structures which can contain millions of degrees of freedom is performed. The detailed description...

A frequency-domain method has been developed to predict and comprehensively analyse the limit-cycle flutter-induced vibrations in bladed discs and other structures with nonlinear contact interfaces. The method allows, for the first time, direct calculation of the limit-cycle amplitudes and frequencies as functions of contact interface parameters an...

The design of high cycle fatigue resistant bladed disks requires the ability to predict the expected damping of the structure in order to evaluate the dynamic behaviour and ensure structural integrity. Highly sophisticated software codes are available today for this nonlinear analysis but their correct use requires a good understanding of the corre...

The newly-revealed phenomenon of reduction of forced response levels in a mistuned bladed disc to levels significantly (e.g. by a factor of two and more) lower than that of its tuned counterpart is studied in detail on an example of a realistic bladed disc. Statistical properties of the amplification factor of the mistuned forced response calculate...

A highly accurate and computationally efficient method is proposed for reduced modelling of jointed structures in frequency domain analysis of nonlinear steady-state forced response. The method has significant advantages compared with the popular variety of mode synthesis methods or forced response matrix methods and can be easily implemented in th...

The modelling of friction contact interfaces in structural dynamics attracts much interest in the gas turbine industry. In order to obtain reliable predictions of typical friction interfaces, such as encountered in under platform dampers or blade roots, accurate characteristics of friction interfaces must be provided to the analysis. It must be ens...

An integrated experimental-numerical study of forced response for a mistuned bladed disc has been performed. A full chain for the predictive forced response analysis has been developed including data exchange between the CFD code and a code for the prediction of the nonlinear forced response for a bladed disc. The experimental measurements are perf...

This paper presents a frequency domain method for the location, characterization, and identification of localized nonlinearities in mechanical systems. The nonlinearities are determined by recovering nonlinear restoring forces, computed at each degree-of-freedom (DOF). Nonzero values of the nonlinear force indicate nonlinearity at the corresponding...

An effective method has been developed to calculate the sensitivity of the resonance peak frequency and forced response level to variation of parameters of nonlinear friction contact interfaces and excitation. The method allows determination of the sensitivity characteristics simultaneously with the resonance peak frequency and response level calcu...

An effective method is developed for calculation of the sensitivity and robustness of the forced response levels for strongly nonlinear structures. The sensitivity coefficients are determined with respect to parameters of friction contact interfaces, parameters of linear components of an assembled structure, frequency and level of excitation forces...

A method has been developed for high-accuracy analysis of forced response levels for mistuned bladed discs vibrating in gas flow. Aerodynamic damping, the interaction of vibrating blades through gas flow and the effects of structural and aerodynamic mistuning are included in the bladed disc model. The method is applicable to cases of high mechanica...

This paper presents a frequency domain method for the characterization and identification of localized nonlinearities in mechanical systems. The nonlinearities are determined by recovering nonlinear restoring forces which are computed at each DOF. The non-zero values of the nonlinear force indicate nonlinearity at the corresponding DOFs and the var...

A generic method for analysis of nonlinear forced response for bladed disks with friction dampers of different designs has been developed. The method uses explicit finite element modeling of dampers, which allows accurate description of flexibility and, for the first time, dynamic properties of dampers of different designs in multiharmonic analysis...

In this paper robust maximum forced response reduction strategies based on a "large mistuning" concept are introduced, including both (i) random and (ii) deterministic approaches. An industrial bladed fan disk serves as an application example for a reliability assessment of the aforementioned strategies using two well-established tools for uncertai...

An efficient method is developed to calculate stochastic and uncertainty characteristics of forced response for nonlinear vibrations of bladed disks with friction and gap contact interfaces. Uncertainty ranges, statistical characteristics, and probability density functions for forced response levels are determined directly without any sampling proc...

Vast majority of machinery structures are assembled structures: they consist of two or, usually, more components assembled together and these joined components interact with each other at friction contact interfaces. The forces acting at friction contact interfaces are generally strongly nonlinear. Among many sources of the nonlinearity of the inte...

An effective method has been developed to calculate sensitivity of the resonance peak frequency and forced response level to variation of parameters of nonlinear friction contact interfaces and excitation. The method allows determination of the sensitivity characteristics simultaneously with the resonance peak frequency and response level calculate...

In this paper, we present a methodology and results from an experimental investigation of forced vibration response for a bladed disk with fitted underplatform “cottage-roof” friction dampers, together with the corresponding numerical predictions. A carefully designed and constructed rotating test rig is used to make precise measurements, which inv...

The problem of estimating the mutual interaction of the effects of Coriolis forces and of blade mistuning on the vibration characteristics of bladed disks is addressed in this paper The influence of different degrees of mistuning on forced response and amplification factors are studied in the presence of Coriolis forces and then compared to their n...

A method has been developed to calculate directly resonance frequencies and resonance amplitudes as functions of design parameters or as a function of excitation levels. The method provides, for the first time, this capability for analysis of strongly nonlinear periodic vibrations of bladed disks and other structures with nonlinear interaction at c...

In this paper, robust maximum forced response reduction strategies based on a “large mistuning” concept are introduced, including both (i) probabilistic and (ii) deterministic approaches. An industrial bladed fan disc serves as an application example for a reliability assessment of the aforementioned strategies using two well-established tools for...

An efficient method is developed to calculate stochastic and uncertainty characteristics of forced response for nonlinear vibrations of bladed discs with friction and gap contact interfaces. Uncertainty ranges, statistical characteristics and probability density functions for forced response levels are determined directly without any sampling proce...

Advanced structural dynamic models for both wedge and split underplatform dampers have been developed. The new damper models take into account inertia forces and the effects of normal load variation on stick-slip transitions at the contact interfaces. The damper models are formulated for the general case of multiharmonic forced response analysis. A...

In this paper we present a methodology and results from an experimental investigation of forced vibration response for a bladed disk with fitted under-platform ‘cottage-roof’ friction dampers, together with the corresponding numerical predictions. A carefully-designed and constructed rotating test rig is used to make precise measurements which invo...

In this paper a comprehensive analysis of steady-state forced response is performed for the case of a system with snap-through nonlinear springs. Stiffness characteristics of these springs include cubic and linear terms and the linear stiffness term is negative. There are a very restricted number of solutions found in literature for such type of no...

An approach is developed to analyze the multiharmonic forced response of large-scale finite element models of bladed disks taking account of the nonlinear forces acting at the contact interfaces of blade roots. Area contact interaction is modeled by area friction contact elements which allow for friction stresses under variable normal load. unilate...

A method has been developed to calculate directly resonance frequencies and resonance amplitudes as functions of design parameters or as a function of excitation levels. The method provides, for a first time, this capability for analysis of strongly nonlinear periodic vibrations of bladed discs and other structures with nonlinear interaction at con...

Advanced structural dynamic models for both wedge and split underplatform dampers have been developed. The new damper models take into account inertia forces and the effects of normal load variation on stick-slip transitions at the contact interfaces. The damper models are formulated for the general case of multiharmonic forced response analysis. A...

The paper presents the results of a study looking into changes in the forced response levels of bladed disc assemblies subject to both structural and aerodynamic mistuning. A whole annulus FE model, representative of a civil aero-engine fan with 26 blades was used in the calculations. The forced response of all blades of 1000 random mistuned patter...

A representative model of aero-engine test rig has been built, comprising the following basic components: rotor, shaft, casing, flexible support structure and bearing housings. One of the bearing housings is designed in such a way that the stiffness along one radial direction is adjustable, and can be set between linear and strongly nonlinear. In t...

An effective method is proposed to calculate sensitivity of nonlinear forced response levels for bladed discs with friction contact interfaces to variation of parameters of these interfaces, including clearances and interferences. First and second order sensitivity coefficients together with ranges of high fidelity for forced response and the sensi...

An efficient method for analysis of nonlinear vibrations of mistuned bladed disk assemblies has been developed. This development has facilitated the use of large-scale finite element models for realistic bladed disks, used hitherto in analysis of linear vibration, to be extended for the analysis of nonlinear multiharmonic vibration. The new method...

The paper summarises the results of a study investigating the correlation between the aerodynamic blade-to-blade coupling in mistuned bladed disc assemblies and the level of forced response. The focus was placed on the torsional mode of vibration, where blades’ coupling through the disc is weak, exposing the effects of aerodynamic coupling. The for...

An effective method for direct parametric analysis of periodic nonlinear forced response of bladed disks with friction contact interfaces has been developed. The method allows, forced response levels to be calculated directly as a function of contact interface parameters such as the friction coefficient, contact surface stiffness (normal and tangen...

An accurate and robust method has been developed for the general multiharmonic analysis of forced periodic vibrations of bladed discs subjected to abrupt changes of elastic and damping properties at contact nodes located on the interfaces of the components. The approach is based on an analytical formulation of friction contact interface elements wh...

An efficient method for analysis of nonlinear vibrations of mistuned bladed disc assemblies has been developed. As a result, this development has facilitated the use of large-scale finite element models for realistic bladed discs, as used hitherto in analysis of linear vibration, to be extended for the analysis of nonlinear multiharmonic vibration....

New efficient models have been developed to describe dynamic friction effects in order to facilitate analysis of the vibration of bladed disks in the time domain. These friction models describe friction forces occurring at contact interfaces under time-varying normal load variations, including cases of separation. The friction models developed allo...

A method for analysis of essentially nonlinear vibrations of cyclically symmetric structure has been developed. Two major cases are analysed: (i) steady-state periodic multiharmonic vibrations; (ii) transient vibrations. The method allows exact calculation of the essentially nonlinear vibrations to be performed using a model for only one period of...

An effective method has been developed for analysis of the multiharmonic forced response of large-scale finite element models of bladed discs with contact interfaces at blade roots. Area contact elements are developed to model nonlinear forces acting at the contact surfaces. The elements allow for unilateral normal and tangential friction contact f...

In the paper, the problem of determining of the worst mistuning patterns is formulated and solved as an optimization problem. Maximum resonant amplitudes searched across the many nodes of a large-scale finite element model of a mistuned bladed disc and across all the excitation frequencies in a given range are combined into an objective function. I...