Effects of blade configuration parameters on helicopter rotor structural dynamics and whirl tower loads

2016 ◽  
Vol 120 (1224) ◽  
pp. 271-290 ◽  
Author(s):  
M. Rohin Kumar ◽  
C. Venkatesan
Keyword(s):  
Structural Dynamics ◽  
Dynamic Characteristics ◽  
Geometric Parameters ◽  
Helicopter Rotor ◽  
Mode Shapes ◽  
Structural Dynamic ◽  
Rotating Blade ◽  
Structural Dynamic Characteristics ◽  
Straight Portion ◽  
General Geometry

ABSTRACTThe influence of the blade geometric parameters on the structural dynamic characteristics, response and loads of a helicopter rotor under hover condition in a whirl tower was investigated. A general geometry was considered for the rotor blade which included configuration parameters like root offset, torque offset, pre-twist, pre-cone, pre-droop, pre-sweep, tip-sweep and tip-anhedral. The option of placing concentrated masses at any location on the blade was also included. Natural frequencies and the corresponding mode shapes of the rotating blade were obtained by solving the linear, undamped structural dynamics model in the finite element domain. For calculating the response and loads on the rotor, the complete aeroelastic equation was solved in modal space. Aerodynamic models used in the aeroelastic loads calculations were Peters-He dynamic wake theory for inflow and themodifiedONERA dynamic stall theory for airloads calculations. From the study, the blade structural dynamic characteristics are found to be sensitive to variation in blade geometric parameters. Tip-sweep was found to have significant effects on root oscillatory moments. The moments at the tip junction with the straight portion of the blade were found to be substantially affected by tip-sweep and tip-anhedral.

scholarly journals Aerothermoelastic Analysis of a Hypersonic Vehicle Based on Thermal Modal Reconstruction

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Zhiqiang Chen ◽  
Yonghui Zhao
Keyword(s):  
Dynamic Characteristics ◽  
Hypersonic Vehicle ◽  
Mode Shapes ◽  
Aerodynamic Heating ◽  
Reconstruction Method ◽  
Structural Dynamic ◽  
Kriging Interpolation Method ◽  
Heating Effects ◽  
Aeroelastic Analysis ◽  
Structural Dynamic Characteristics

Hypersonic vehicles operate in a severe aerodynamic heating environment, which has a significant impact on their structural dynamic characteristics. Therefore, aerodynamic heating effects cannot be ignored when performing an aeroelastic analysis for a hypersonic vehicle. However, incorporating aerodynamic heating effects into the fluid-structural coupling analysis will result in extreme computational costs. Actually, after experiencing a sustained flight in a fixed state, the vehicle will eventually reach the thermodynamic equilibrium. Thus, the aeroelastic analysis can be efficiently performed by using the structural dynamic characteristics of the heated vehicle operating in each equilibrium state. The effects of aerodynamic heating show that the modal frequencies and modal shapes of the flexible structure are bound to change significantly in comparison with the unheated structure. In this paper, a method of thermal modal reconstruction is developed in order to directly generate the structural mode shapes and frequencies within the given parameter space without having to solve a high-fidelity thermal and structural problem. Once the modal data are available, the multivariate interpolation in a tangent space to Grassmann manifold is used to generate the modal matrix at the arbitrary selected parameter point. Besides, the Kriging interpolation method is used to establish the approximate relationships between natural frequencies and sampling points. Finally, an example of an aerodynamic heated control surface structure is used to validate the effectiveness of the proposed aerothermoelastic framework. It is demonstrated that the developed thermal modal reconstruction method has good robustness, very high computational efficiency, and sufficient accuracy over a wide parametric domain.

Analysis of Dynamic Characteristics of Excavator Working Device Based on ANSYS+Pro/E

2014 ◽  
Vol 971-973 ◽  
pp. 372-375
Author(s):  
Di Zhao ◽  
Wei Yang ◽  
Qian Jin Liu ◽  
Xiao Hui Jin ◽  
Sheng Xu
Keyword(s):  
Dynamic Characteristics ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Mode Shapes ◽  
Element Analysis ◽  
Structural Dynamic ◽  
The Finite Element Analysis ◽  
Structural Dynamic Characteristics ◽  
Three Dimensional Models ◽  
Working Device

Complex operating environment makes excavator working device become the main wearing parts ,In this paper,builds three-dimensional models of the excavator working device using Pro/E. And selects the working device typical operating conditions which is in the maximum discharge height ,then imports it into the finite element analysis software ANSYS - Workbench module. For the purpose of acquiring its natural frequencies and mode shapes, it conducts the modal analysis by setting the material properties, meshing and boundary conditions,which provided foundation for the optimal design of hydraulic excavator overall vibration analysis and structural dynamic characteristics.

Study on Flow-Induced Vibration Characteristics of Hydraulic Hoist of Large-Span Upwelling Radial Steel Gate

2011 ◽  
Vol 117-119 ◽  
pp. 241-246
Author(s):  
Zhen Hai Gao ◽  
Gen Hua Yan ◽  
Peng Liu ◽  
Fa Zhan Chen ◽  
Fei Ming Lv
Keyword(s):  
Dynamic Characteristics ◽  
Vibration Characteristics ◽  
Vibration Response ◽  
Flow Induced Vibration ◽  
Structural Dynamic ◽  
Large Span ◽  
Response Characteristics ◽  
Lever Action ◽  
Structural Dynamic Characteristics ◽  
Steel Gate

In this paper we conduct study on flow-induced vibration of large-span upwelling radial steel Gate and its hydraulic hoist. Place an emphasis on vibration response characteristics under two working conditions of diversion and drainage, which proves the safety of hydraulic hoist gate vibration caused by gate vibration. Firstly, we study on dynamic characteristics of fluid-structure interaction of association system of gate and start and stop lever, reveals the discipline of the effect fluid having on structural dynamic characteristics. On this basis, flow-induced vibration characteristics under two conditions of with and without start and stop lever action considered. The results indicate that the gate vibration response with hydraulic hoist used decreases, which explains start and stop lever has certain effect of restraining vibration on gate vibration. In addition, under the working condition of drainage the vibration magnitude of start and stop lever is smaller than that of gate body, which explains there is damping action during transference of gate vibration through start and stop lever. The results find out that on the assumption of optimized gate structure and hydraulic arrangement, it is practicable, safe and reliable to adopt hydraulic hoist. The achievement has directive significance on similar projects construction in the future

Identification and Prediction of Frame Structure Dynamics by Spatial Matrix Identification Method

2000 ◽  
Author(s):  
Masaaki Okuma ◽  
Ward Heylen ◽  
Hisayoshi Matsuoka ◽  
Paul Sas
Keyword(s):  
Boundary Condition ◽  
Dynamic Characteristics ◽  
Structural Modification ◽  
Test Structure ◽  
Frame Structure ◽  
Structural Dynamic ◽  
Identification Method ◽  
Input Multiple Output ◽  
Structural Dynamic Characteristics ◽  
Single Input

Abstract This paper presents the result of using an experimental spatial matrix identification method to predict the dynamics of a frame structure under a different boundary condition. The single-input-multiple-output frequency response functions of the test structure under the free-free boundary condition are measured by hammer testing. Using the FRFs, a set of spatial matrices is determined to represent its structural dynamic characteristics by the method. Then, using the identified spatial matrices, the dynamic characteristics of the test structure under the boundary condition of clamping 4 points is predicted. The prediction is practically accurate. The result of the prediction demonstrates that the spatial matrices identified by the method can be used for structural modification and substructure synthesis in the field of computer aided mechanical engineering.

Serviceability design factors for wind-sensitive structures

2010 ◽  
Vol 37 (5) ◽  
pp. 728-738 ◽  
Author(s):  
A. Pozos-Estrada ◽  
H. P. Hong ◽  
J. K. Galsworthy
Keyword(s):  
Standard Deviation ◽  
Dynamic Characteristics ◽  
Human Perception ◽  
Wind Loading ◽  
Peak Acceleration ◽  
Structural Dynamic ◽  
Annual Probability ◽  
Structural Dynamic Characteristics ◽  
Wind Characteristics ◽  
Design Factors

Wind-sensitive buildings can experience excessive vibrations that cause discomfort and interruption of the activities of the inhabitants of the buildings. To ensure the desired serviceability, codes, standards, and their commentaries have proposed perception curves that limit the expected (or mean) peak acceleration or standard deviation of the acceleration of the buildings. These perception curves are developed based on perceived vibration alone and do not consider the uncertainty in structural dynamic characteristics (i.e., natural frequency of vibration and ratio of damping) and loads such as the wind loading. Therefore, the annual probability that the perception curve is not exceeded for a building whose design is based on the perception curve is unknown. In this study, serviceability design factors are calibrated for selected targeted annual probability of perception levels by considering the uncertainty in the structural dynamic characteristics, wind characteristics, as well as in the human perception of motion. These serviceability design factors are to be used with the estimated mean peak acceleration caused by along-wind and cross-wind excitations given in the commentaries of the current National building code of Canada. The use of calibrated serviceability design factors for design checking is illustrated with a numerical example.

Identification and Prediction of Frame Structure Dynamics by Spatial Matrix Identification Method

2001 ◽  
Vol 123 (3) ◽  
pp. 390-394 ◽  
Author(s):  
Masaaki Okuma ◽  
Ward Heylen ◽  
Hisayoshi Matsuoka ◽  
Paul Sas
Keyword(s):  
Boundary Condition ◽  
Dynamic Characteristics ◽  
Test Structure ◽  
Frame Structure ◽  
Structural Dynamic ◽  
Various Boundary Conditions ◽  
Identification Method ◽  
Input Multiple Output ◽  
Structural Dynamic Characteristics ◽  
Single Input

This paper presents the results of using an experimental spatial matrix identification method to predict the dynamics of a frame structure under various boundary conditions. The single-input-multiple-output frequency response functions (FRFs) of the test structure under the free-free boundary condition are measured by hammer testing. Using the FRFs, a set of spatial matrices is constructed in order to represent the structural dynamic characteristics of the system by the new method. Using the spatial matrices, the dynamic characteristics of the test structure under the boundary condition of clamping 4 points is predicted. The prediction is adequately accurate for practical application. The results of the prediction demonstrate that the spatial matrices identified by this method can be used for structural modification and substructure synthesis in the field of computer-aided mechanical engineering.

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