The Design and Evaluation of a Supercritical-Speed Helicopter Power-Transmission Shaft

1967 ◽  
Vol 89 (4) ◽  
pp. 719-727 ◽  
Author(s):  
R. H. Prause ◽  
H. C. Meacham ◽  
J. E. Voorhees
Keyword(s):  
Power Transmission ◽  
Small Diameter ◽  
Helicopter Rotor ◽  
Design Parameters ◽  
Viscous Damper ◽  
Critical Speeds ◽  
The Third ◽  
Transmission Shaft ◽  
Outside Diameter ◽  
Supercritical Speed

A series of research programs with small-diameter, supercritical-speed power-transmission shafting has led to the development of design techniques for the application of one or two viscous dampers to control shaft vibrations through as many as 20 critical speeds. These techniques have been used to design a large, 338.5-in-long helicopter rotor synchronizing shaft using aluminum tubing with an outside diameter of 4.50 in. and a wall thickness of 0.12 in. A single viscous damper located 30.0 in. from one end of the shaft has been used to successfully operate the shaft through its first five critical speeds. The design parameters and experimental results for this shaft are discussed, along with a description of the application of modal balancing at the third, fourth, and fifth critical speeds.

Vibration-Based Early Crack Diagnosis With Machine Learning for Spur Gears

2020 ◽  
Author(s):  
Fatih Karpat ◽  
Ahmet Emir Dirik ◽  
Onur Can Kalay ◽  
Oğuz Doğan ◽  
Burak Korcuklu
Keyword(s):  
Machine Learning ◽  
Fault Diagnosis ◽  
High Speed ◽  
Crack Detection ◽  
Power Transmission ◽  
Calculated Data ◽  
Design Parameters ◽  
Tooth Stiffness ◽  
Vibration Responses ◽  
Root Crack

Abstract Gear mechanisms are one of the most significant components of the power transmission systems. Due to increasing emphasis on the high-speed, longer working life, high torques, etc. cracks may be observed on the gear surface. Recently, Machine Learning (ML) algorithms have started to be used frequently in fault diagnosis with developing technology. The aim of this study is to determine the gear root crack and its degree with vibration-based diagnostics approach using ML algorithms. To perform early crack detection, the single tooth stiffness and the mesh stiffness calculated via ANSYS for both healthy and faulty (25-50-75-100%) teeth. The calculated data transferred to the 6-DOF dynamic model of a one-stage gearbox, and vibration responses was collected. The data gathered for healthy and faulty cases were evaluated for the feature extraction with five statistical indicators. Besides, white Gaussian noise was added to the data obtained from the 6-DOF model, and it was aimed at early fault diagnosis and condition monitoring with ML algorithms. In this study, the gear root crack and its degree analyzed for both healthy and four different crack sizes (25%-50%-75%-100%) for the gear crack detection. Thereby, a method was presented for early fault diagnosis without the need for a big experimental dataset. The proposed vibration-based approach can eliminate the high test rig construction costs and can potentially be used for the evaluation of different working conditions and gear design parameters. Therefore, catastrophic failures can be prevented, and maintenance costs can be optimized by early crack detection.

Subsea Cable Stability on Rocky Seabeds: Comparison of Field Observations Against Conventional and Novel Design Methods

2018 ◽  
Author(s):  
Terry Griffiths ◽  
Scott Draper ◽  
Liang Cheng ◽  
Feifei Tong ◽  
Antonino Fogliani ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Power Transmission ◽  
Small Diameter ◽  
Oil And Gas Industry ◽  
Operational Reliability ◽  
Design Methods ◽  
Gas Industry ◽  
Integrity Management ◽  
Tidal Stream ◽  
Almost All

As offshore renewable energy projects progress from concept demonstration to commercial-scale developments there is a need for improved approaches beyond conventional cable engineering design methods that have evolved from larger diameter pipelines for the oil and gas industry. New approaches are needed to capture the relevant physics for small diameter cables on rocky seabeds to reduce the costs and risks of power transmission and increase operational reliability. This paper reports on subsea cables that MeyGen installed for Phase 1a of the Pentland Firth Inner Sound tidal stream energy project. These cables are located on rocky seabeds in an area where severe metocean conditions occur. ROV field observation of these cables shows them to be stable on the seabed with little or no movement occurring over almost all of the cable routes, despite conventional engineering methods predicting significant dynamic movement. We cite recent research undertaken by the University of Western Australia (UWA) to more accurately assess the hydrodynamic forces and geotechnical interaction of cables on rocky seabeds. We quantify the conformity between the cables and the undulating rocky seabed, and the distributions of cable-seabed contact and spanning via simulations of the centimetric-scale seabed bathymetry. This analysis leads to calculated profiles of lift, drag and seabed friction along the cable, which show that all of these load and reaction components are modelled in an over-conservative way by conventional pipeline engineering techniques. Overall, our analysis highlights that current cable stability design can be unnecessarily conservative on rocky seabeds. Our work foreshadows a new design approach that offers more efficient cable design to reduce project capex and enhance through-life integrity management.

Demonstration of a Unified Approach to the Balancing of Flexible Rotors

1981 ◽  
Vol 103 (1) ◽  
pp. 101-107 ◽  
Author(s):  
M. S. Darlow ◽  
A. J. Smalley ◽  
A. G. Parkinson
Keyword(s):  
Power Transmission ◽  
Substantial Reduction ◽  
Influence Coefficient ◽  
Flexible Rotor ◽  
Unified Approach ◽  
Test Rig ◽  
Multiple Mode ◽  
Flexible Rotors ◽  
Transmission Shaft ◽  
Rotor Balancing

A flexible rotor balancing procedure, which incorporates the advantages and eliminates the disadvantages of the modal and influence coefficient procedures, has been developed and implemented. This new procedure, referred to as the Unified Balancing Approach, has been demonstrated on a supercritical power transmission shaft test rig. The test rig was successfully balanced through four flexural critical speeds with a substantial reduction in effort as compared with the effort required in modal and influence coefficient balancing procedures. A brief discussion of the Unified Balancing Approach and its relationship to the modal and influence coefficient methods is presented. A series of tests which were performed to evaluate the effectiveness of various balancing techniques are described. The results of the Unified Balancing Approach tests are presented and discussed. These results confirm the superiority of this balancing procedure for the supercritical shaft test rig in particular and for multiple-mode balancing in general.

scholarly journals A Portable Sisal Decorticator for Kenyan Farmers

2006 ◽  
Vol 1 (2) ◽  
Author(s):  
Benjamin J. Snyder ◽  
Joe Bussard ◽  
Jim Dolak ◽  
Tim Weiser
Keyword(s):  
Energy Consumption ◽  
Arid Regions ◽  
Material Selection ◽  
Small Diameter ◽  
Optimal Solution ◽  
Design Parameters ◽  
Small Scale ◽  
Quality Testing ◽  
The Arid Regions ◽  
Assembly Constraints

This project analyzed and redesigned the various components of a previously designed sisal decorticator prototype. The sisal plant is easily grown in the arid regions of Kenya and its fiber has widespread industrial and consumer applications. Competition from Brazilian and Chinese sisal growers has made it difficult for small-scale Kenyan sisal farmers to yield a profit. Decorticator machines strip the usable fiber from the sisal leaves. A strong market exists in Kenya and beyond for an affordable and capable decortication device. Based on interaction with University of Nairobi students and faculty, design parameters were assessed and adapted to create a working prototype to meet these needs. Throughout the design process, affordability, energy consumption, transportability, reliability, on-site material and assembly constraints were taken into account. The designs chosen accomplished the project requirements by minimizing cost through material selection and ease of manufacture, and provided adjustable parameters in order to facilitate decortication quality testing. A vertical feed, small diameter decorticator with steel blades transportable via a steel frame with two wheels was determined to be the optimal solution. Testing with actual sisal and variable components enabled quality to be assessed as well as ensured that the designed prototype operated correctly and safely.

Fatigue failure of a hollow power transmission shaft

2002 ◽  
Vol 9 (4) ◽  
pp. 457-467 ◽  
Author(s):  
S.K. Bhaumik ◽  
R. Rangaraju ◽  
M.A. Parameswara ◽  
M.A. Venkataswamy ◽  
T.A. Bhaskaran ◽  
...  
Keyword(s):  
Fatigue Failure ◽  
Power Transmission ◽  
Transmission Shaft

Genetic Optimization of Geometrical Parameters of High Speed Rotor

2015 ◽  
Author(s):  
Behnam Ghalamchi ◽  
Adam Kłodowski ◽  
Jussi T. Sopanen ◽  
Aki M. Mikkola
Keyword(s):  
High Speed ◽  
Turbine Rotor ◽  
Optimization Techniques ◽  
Design Parameters ◽  
Geometrical Parameters ◽  
Campbell Diagram ◽  
Critical Speeds ◽  
Operation Speed ◽  
Wide Range ◽  
Speed Range

The main scope of this paper is optimization of high speed rotor systems by using Evolutionary Algorithm. The target of the optimization is finding geometrical parameters of the shaft, in such a way that the critical speeds are not occurring in the operation speed range. Rotating machines have a wide range of applications in industrial machinery and applying numerical optimization techniques helps engineers to improve the performance of rotor bearing systems. A schematic of a turbine rotor system is studied. The rotor is modeled using finite element method and Timoshenko beam elements having four degrees of freedom (DOF) per node — two translational and two rotational. Critical speeds are identified using Campbell diagram. The outcome of the simulation is looking to find the widest safe margin for operation speed range without any critical speed in Campbell diagram within the operation range. Design parameters for optimization are overhang shafts lengths and diameters. Several simulation runs with different variables shows a significant effect of these parameters in dynamic behavior of the system. Comparison of the results with the basic design of turbine rotor reveals that all constraints are satisfied.

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