scholarly journals Structural Design Research Through Finite Element Method (FEM) for a Compressor Disc

2020 ◽  
Vol 9 (4) ◽  
pp. 475-481
Keyword(s):  
Design Research ◽  
Rotating Disc ◽  
Corner Crack ◽  
Load Bearing ◽  
Bolt Holes ◽  
Critical Location ◽  
Critical Components ◽  
Hoop Stresses ◽  
Gas Turbine Compressor ◽  
Crack Growth Model

Compressor Discs are subjected to various loads like pressure load, tensile, compressive, buckling, temperature, gravity, etc. during its operation. There are load bearing members and non-load bearing members. The load bearing members are critical components of the disc. Due to these loading condition radial and hoop stresses are generated in the discs. When these stresses exceed yield strength of the material failure occurs. To determine the various stresses acting on a gas turbine compressor disc rotating with constant velocity, initially the Disc is modeled and analyzed using Commercial FEA codes focused on bolt holes and nominal stresses on the cracked disc (a corner crack at a hole and then a through-thickness crack between two holes) are determined. These Stresses can be accounted for the development of advanced crack growth model which can predict the propagation of crack from the critical location of the rotating disc.

A new approach for pre-stressing of rail-end-bolt holes

2016 ◽  
Vol 231 (12) ◽  
pp. 2275-2283 ◽  
Author(s):  
JT Maximov ◽  
GV Duncheva ◽  
IM Amudjev ◽  
AP Anchev ◽  
N Ganev
Keyword(s):  
Fatigue Life ◽  
Fatigue Cracks ◽  
New Technology ◽  
Innovative Technology ◽  
Bolted Joint ◽  
Compressive Stresses ◽  
Process Formation ◽  
Technology Process ◽  
Bolt Holes ◽  
Hoop Stresses

Bolted joint railroad is the subject matter of this paper. Rail joint elements are subjected to cyclic and impact loads as a result of the passage of trains, which causes the origination and growth of fatigue cracks occurring, in most cases, around the bolt holes. Fatigue failure around rail-end-bolt holes is particularly dangerous because it leads to derailment of trains and, consequently, to inevitable accidents. Moreover, the cracking at rail-ends, which starts from bolt hole surface, causes premature rails replacement. The presence of residual compressive hoop stresses around the bolted holes, which is achieved by prestressing of these holes, extends the fatigue life of bolted joint railroads. This article presents an innovative technology for pre-stressing of rail-end-bolt holes, implemented on a vertical machining centre of Revolver vertical (RV) type. Two consecutive operations are involved in the manufacturing technology process: formation of the hole by drilling, reaming and making of a chamfer through a new combined cutting tool; cold hole working by spherical motion cold working through a new tool equipment, which minimizes the axial force on the reverse stroke. The new technology introduces beneficial residual compressive stresses around the bolted holes thereby preventing the fatigue cracks growth and increasing the fatigue life of these openings.

Neural Network Models for Usage Based Remaining Life Computation

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Girija Parthasarathy ◽  
Sunil Menon ◽  
Kurt Richardson ◽  
Ahsan Jameel ◽  
Dawn McNamee ◽  
...  
Keyword(s):  
Neural Network ◽  
Computation Time ◽  
Network Models ◽  
Operating Conditions ◽  
Neural Network Models ◽  
Operational Conditions ◽  
Actual Operating ◽  
Critical Location ◽  
Critical Components ◽  
Stress Models

In engine structural life computations, it is common practice to assign a life of certain number of start-stop cycles based on a standard flight or mission. This is done during design through detailed calculations of stresses and temperatures for a standard flight, and the use of material property and failure models. The limitation of the design phase stress and temperature calculations is that they cannot take into account actual operating temperatures and stresses. This limitation results in either very conservative life estimates and subsequent wastage of good components or in catastrophic damage because of highly aggressive operational conditions, which were not accounted for in design. In order to improve significantly the accuracy of the life prediction, the component temperatures and stresses need to be computed for actual operating conditions. However, thermal and stress models are very detailed and complex, and it could take on the order of a few hours to complete a stress and temperature simulation of critical components for a flight. The objective of this work is to develop dynamic neural network models that would enable us to compute the stresses and temperatures at critical locations, in orders of magnitude less computation time than required by more detailed thermal and stress models. The current paper describes the development of a neural network model and the temperature results achieved in comparison with the original models for Honeywell turbine and compressor components. Given certain inputs such as engine speed and gas temperatures for the flight, the models compute the component critical location temperatures for the same flight in a very small fraction of time it would take the original thermal model to compute.

Boundary integral equation stress analysis of a rotating disc with a corner crack

1983 ◽  
Vol 18 (4) ◽  
pp. 231-237 ◽  
Author(s):  
C L Tan
Keyword(s):  
Integral Equation ◽  
Boundary Integral Equation ◽  
Three Dimensional ◽  
Circular Crack ◽  
Boundary Integral ◽  
Rotating Disc ◽  
Corner Crack ◽  
Linear Elastic ◽  
Numerical Formulation ◽  
Corner Cracks

The analytical and numerical formulation of the boundary integral equation (BIE) method are outlined for the general case in linear elasticity. Using this method, three-dimensional linear elastic fracture mechanics analyses of a rotating disc with a corner crack at its bore are carried out. The cases considered are for a disc with external to internal radius ratio of 8 and with thickness equal to the diameter of the central bore. Two different crack shapes, namely, a quarter-circular crack and a quarter-elliptical crack with ellipse aspect ratio of 0.75, are analysed. For each of these shapes, corner cracks penetrating 50 per cent and 75 per cent of the disc thickness are treated. Stress intensity factor solutions for these cracks are presented for the centrifugal loading condition, as well as when the disc is subjected to a radial tensile stress at its external circumferential periphery.

scholarly journals Biomaterial Enhanced Regeneration Design Research for Skin and Load Bearing Applications

2019 ◽  
Vol 10 (1) ◽  
pp. 10 ◽  
Author(s):  
Dale Feldman
Keyword(s):  
Design Research ◽  
Clinical Performance ◽  
Biological Response ◽  
Current Clinical Practice ◽  
Cellular Activity ◽  
Design Constraints ◽  
Future Directions ◽  
Load Bearing ◽  
Principles Of Design ◽  
Design Options

Biomaterial enhanced regeneration (BER) falls mostly under the broad heading of Tissue Engineering: the use of materials (synthetic and natural) usually in conjunction with cells (both native and genetically modified as well as stem cells) and/or biological response modifiers (growth factors and cytokines as well as other stimuli, which alter cellular activity). Although the emphasis is on the biomaterial as a scaffold it is also the use of additive bioactivity to enhance the healing and regenerative properties of the scaffold. Enhancing regeneration is both moving more toward regeneration but also speeding up the process. The review covers principles of design for BER as well as strategies to select the best designs. This is first general design principles, followed by types of design options, and then specific strategies for applications in skin and load bearing applications. The last section, surveys current clinical practice (for skin and load bearing applications) including limitations of these approaches. This is followed by future directions with an attempt to prioritize strategies. Although the review is geared toward design optimization, prioritization also includes the commercializability of the devices. This means a device must meet both the clinical performance design constraints as well as the commercializability design constraints.

Computational Fatigue Analysis of the Pin-Loaded Lug with Quarter-Elliptical Corner Crack

2017 ◽  
Vol 09 (04) ◽  
pp. 1750058 ◽  
Author(s):  
Slobodanka Boljanović ◽  
Stevan Maksimović ◽  
Andrea Carpinteri ◽  
Boško Jovanović
Keyword(s):  
Crack Growth ◽  
Stress Ratio ◽  
Crack Path ◽  
The Finite Element Method ◽  
Growth Path ◽  
Growth Data ◽  
Corner Crack ◽  
Nonlinear Stress ◽  
Crack Growth Path ◽  
Crack Growth Model

In the present paper, mathematical models based on a new fracture mechanics methodology are developed for the failure analysis of an attachment lug with one/two quarter-elliptical crack(s) emanating from a hole. The strength of lug subjected to cyclic loading is theoretically examined through the following issues: the stress analysis, the estimation of life up to failure and the crack path evolution. The nonlinear stress field along the crack front is simulated by using the [Formula: see text]-integral method together with the finite element method. Furthermore, analytical and numerical methods are employed for the stress intensity factor calculation. The stress-ratio dependence crack growth model is applied in order to evaluate both the life up to failure and the crack growth path. The proposed models are validated through available crack growth data, and the comparison between different results is satisfactory.

The Role of the SLP in Autism Spectrum Disorder Screening and Assessment

2008 ◽  
Vol 15 (2) ◽  
pp. 50-59 ◽  
Author(s):  
Amy Philofsky
Keyword(s):  
Language Development ◽  
Critical Role ◽  
Children With Autism ◽  
Autism Spectrum ◽  
Children With Asd ◽  
Prevalence Estimates ◽  
Notable Increase ◽  
Screening Assessment ◽  
Critical Components

AbstractRecent prevalence estimates for autism have been alarming as a function of the notable increase. Speech-language pathologists play a critical role in screening, assessment and intervention for children with autism. This article reviews signs that may be indicative of autism at different stages of language development, and discusses the importance of several psychometric properties—sensitivity and specificity—in utilizing screening measures for children with autism. Critical components of assessment for children with autism are reviewed. This article concludes with examples of intervention targets for children with ASD at various levels of language development.

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