Structural damage in materials evolves over time due to growth of fatigue cracks in homogenous materials and a complicated process of matrix cracking, delamination, fiber breakage and fiber matrix debonding in composite materials. In this study, a finite element model of the helicopter rotor blade is used to analyze the effect of damage growth on the modal frequencies in a qualitative manner. P...

Fatigue life estimation is one of the most important design considerations in mechanical parts which are subjected to alternating loads. When loads act along several axes, multiaxial fatigue approach should be used to obtain more accurate results than uniaxial fatigue method. In this paper stress analysis of the steel shaft of a high speed microgenerator rotor with 47750 rpm and 100kW is carrie...

In memoriam Professor Dr. Werner Zeil The microwave spectrum of tricarbon oxide sulphide (3-thioxo-l,2-propadiene-l-one), 0 = C = C = C = S , has been measured in the frequency range from 8 to 40 GHz and includes vibrational satellite lines arising from the vibrational manifold of the lowest-lying doubly-degenerate bending mode i>7. The method of analysis followed the theory of rotation-vibrati...

Rotating shafts are important and responsible components of many machines, such as power generation plants, aircraft engines, machine tool spindles, etc. A transverse shaft crack can occur due to cyclic loading, creep, stress corrosion, and other mechanisms to which rotating machines are subjected. If not detected early, the developing shaft crack can lead to a serious machine damage resulting ...

This work deals with effects of asymmetric stiffness on the dynamic behaviour of the rotor system. The analysis is presented through an extended Lagrangian Hamiltonian mechanics on the asymmetric rotor system, where symmetries are broken in terms of the rotor stiffness. The complete dynamics of asymmetries of rotor system is investigated with a case study. In this work, a mathematical model is ...

On-board rotating machinery subject to multi-axial excitations is encountered in a wide variety of high-technology applications. Such combined with mass unbalance forces play considerable role their integrity because they can cause parametric instability and rotor–stator interactions. Consequently, predicting the rotordynamics such machines crucial avoid triggering undesirable phenomena or at l...

Rotary piezoelectric motors based on converse effect are very competitive in the fields of precision driving and positioning. Miniaturization larger output capability crucial design objectives, efforts structural modification, new materials application optimization control systems persistent but effectiveness is limited. In this paper, resonance rotor excited by stator investigated meshing driv...

Tidal devices are likely to faced with shear flows and subjected various wave climates. The paper presents an experimental study of the combined impacts profile irregular waves on loading a 1/20th scale device operating at peak power extraction. experiments presented were conducted depths facilitate analysis effects flow impact positions in water column. fluid field was measured three different...

In this article, turbulent flow heat transfer in the air gap between rotor and stator of a generator under nonhomogeneous heat flux is studied experimentally. The rotor consists of four symmetrical triangular grooves. The stator surface is smooth and does not include any grooves. The relative heat flux between the rotor and the stator is 1 to 3. Temperature and heat flux are measured locally at...

Crack fault of rotor is one of the most prominent problems faced by magnetic bearing rotor system. In order to improve the safety performance of this kind of machinery, it is necessary to research the vibration characteristics of magnetic bearing cracked rotor system. In this paper, the stiffness model of the crack shaft element was established by the strain energy release rate (SERR) theory. T...