Engineering Critical Assessment of Embedded Flaws in a Pipeline Using a Probabilistic Approach: A Case Study

2011 ◽  
Author(s):  
Daowu Zhou ◽  
Ali Mirzaee-Sisan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Limit State ◽  
Critical Assessment ◽  
Surface Model ◽  
State Function ◽  
Limit State Function ◽  
Element Analysis ◽  
Reliability Method

A probabilistic engineering critical assessment of embedded flaws in a pipeline was carried out as a case study using the limit state function based on both finite element analysis and the failure assessment diagram. The response surface model was used in determining the finite element analysis based limit state function in order to reduce the number of finite element analysis runs. The first order reliability method and second order reliability method were used to determine the probability of failure. This research work highlights the advantage of using specific limit state function for engineering critical assessment of embedded flaws.

Design and Analysis of Manufacturing Component Under Sustainability Considerations: A Case Study of Electronic and Mechanical Indexing Head for Milling Operation

2018 ◽  
Author(s):  
Nand K. Jha ◽  
Mahmoud M. Amin
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cost Estimation ◽  
Minimum Energy ◽  
Solid Modeling ◽  
Milling Machine ◽  
Element Analysis ◽  
Milling Operation ◽  
The Cost

An attempt has been made to design and analyze Indexing Head a very important component in milling operation under sustainability considerations. The design of each component of indexing head is presented along with solid modeling and finite element analysis. The cost estimation for indexing head for milling operation is also presented. The design and finite element analysis of indexing head should be utilized by manufacturers of this very useful device in milling operation. It is used for cutting gears, spirals, splines, etc. The cost estimated of the manufactured indexing head shows it to be within reasonable limits of market. Finite element analysis of each component is safe. An electronic indexing is suggested as an improvement over the mechanical indexing head. A schematic of electronic indexing is presented. The electronic indexing head can be used with milling machine not provided with indexing head and will be portable. The minimum energy needed to manufacture the indexing head is also estimated.

A Review of Optimising the Design of a New Coke Drum Skirt

2019 ◽  
Author(s):  
Alex Berry ◽  
Warren Brown ◽  
Antonio Seijas ◽  
Sarah Cook
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Literature Review ◽  
Thermal Stresses ◽  
Fatigue Cracking ◽  
Element Analysis ◽  
Long Life ◽  
Welded Connection

Abstract Coke drums are subjected to severe thermal cycling with the skirt to shell connection weld being vulnerable to fatigue cracking. It is essential this connection is well designed to ensure a long life before repairs are inevitably required. Much has been written on coke drum skirt design with the aim of reducing the thermal stresses and strains encountered at the skirt connection weld, some designs have removed the weld completely allowing the drum to sit in an “egg-in-cup” arrangement. This paper includes a short literature review discussing Coke drum skirt designs and explains skirt behaviour during the drum cycle that results in eventual skirt cracking. A case study is reviewed in detail for a new pair of coke drums, where the predicted fatigue life of the chosen welded connection is assessed using axisymmetric, quarter symmetry and half symmetry finite element analysis supported by thermocouple data. The optimised design focuses on a conventional tangential design where the effects of the essential variables such as skirt thickness, skirt connection location, skirt-to head-gap and slot design (length, location & spacing) have been modelled and optimised to obtain a skirt design that produces the longest fatigue life for the intended duty cycle. Coke drum skirts must be installed onto the shell to exacting tolerances during manufacture to ensure concentricity and minimal gap between the skirt and shell. A brief overview of how this is achieved will be presented.

scholarly journals Long-Term Performance of Trestle Bridges: Case Study of an Indonesian Marine Port Structure

2020 ◽  
Vol 8 (5) ◽  
pp. 358 ◽  
Author(s):  
Yusak Oktavianus ◽  
Massoud Sofi ◽  
Elisa Lumantarna ◽  
Gideon Kusuma ◽  
Colin Duffield
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Service Life ◽  
Field Measurement ◽  
Field Measurements ◽  
Element Analysis ◽  
Moment Capacity ◽  
Non Destructive

A precast reinforced concrete (RC) T-beam located in seaport Terminal Peti Kemas (TPS) Surabaya built in 1984 is used as a case study to test the accuracy of non-destructive test techniques against more traditional bridge evaluation tools. This bridge is mainly used to connect the berth in Lamong gulf and the port in Java Island for the logistic purposes. The bridge was retrofitted 26 years into its life by adding two strips of carbon fiber reinforced polymer (CFRP) due to excessive cracks observed in the beams. Non-destructive field measurements were compared against a detailed finite element analysis of the structure to predict the performance of the girder in terms of deflection and moment capacity before and after the retrofitting work. The analysis was also used to predict the long-term deflections of the structure due to creep, crack distribution, and the ultimate moment capacity of the individual girder. Moreover, the finite element analysis was used to predict the deflection behavior of the overall bridge due to vehicle loading. Good agreement was obtained between the field measurement and the analytical study. A new service life of the structure considering the corrosion and new vehicle demand is carried out based on field measurement using non-destructive testing. Not only are the specific results beneficial for the Indonesian port authority as the stakeholder to manage this structure, but the approach detailed also paves the way for more efficient evaluation of bridges more generally over their service life.

Investigating the Effect of Weight Reduction of Rod-End in Drag-Link Product with Finite Element Analysis, Fatigue Test, and a Case Study

2020 ◽  
Vol 21 (2) ◽  
pp. 513-518
Author(s):  
Erinç Uludamar ◽  
Mustafa Taş ◽  
Sami Gökberk Biçer ◽  
Cihan Yıldırım ◽  
Ebru Aykut Yıldırım ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Test ◽  
Weight Reduction ◽  
Element Analysis ◽  
Drag Link

Second-Order Reliability Method With First-Order Efficiency

2010 ◽  
Author(s):  
Xiaoping Du ◽  
Junfu Zhang
Keyword(s):  
Limit State ◽  
Saddlepoint Approximation ◽  
Quadratic Function ◽  
Second Order ◽  
State Function ◽  
Limit State Function ◽  
First Order ◽  
Reliability Method ◽  
Order Of Magnitude ◽  
Univariate Function

The widely used First Order Reliability Method (FORM) is efficient, but may not be accurate for nonlinear limit-state functions. The Second Order Reliability Method (SORM) is more accurate but less efficient. To maintain both high accuracy and efficiency, we propose a new second order reliability analysis method with first order efficiency. The method first performs the FORM and identifies the Most Probable Point (MPP). Then the associated limit-state function is decomposed into additive univariate functions at the MPP. Each univariate function is further approximated as a quadratic function, which is created with the gradient information at the MPP and one more point near the MPP. The cumulant generating function of the approximated limit-state function is then available so that saddlepoint approximation can be easily applied for computing the probability of failure. The accuracy of the new method is comparable to that of the SORM, and its efficiency is in the same order of magnitude as the FORM.

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