Overwelding and distortion control for naval surface combatants

2012 ◽  
Author(s):  
T. D. Huang ◽  
M. Harbison ◽  
L. Kvidahl ◽  
D. Niolet ◽  
J. Walks ◽  
...  
Keyword(s):  
Thin Plate ◽  
Early Stage ◽  
Steel Structures ◽  
Ship Design ◽  
Rate Of Change ◽  
Fillet Welds ◽  
Naval Research ◽  
Process Technology ◽  
Thin Steel ◽  
Dimensional Management

As high-strength thin-steel usage in ship design increases, dimensional management becomes very critical to control rework costs and schedule delays in ship production. Prior Office of Naval Research (ONR) and National Shipbuilding Research Program (NSRP) projects have helped Ingalls Shipbuilding to emphasize dimensional control for thin steel structures. Huntington-Ingalls (previous Northrop Grumman Shipbuilding) has, in recent years, substantially increased its emphasis on dimensional management as an enabler to achieving its aggressive goals for the future. These goals include cost and lead time reduction for hull erection and increasing early-stage outfitting. Nevertheless, improvements to shipbuilding facilities and process technology have not kept pace with the rate of change in ship design. Worse, new designs using thinner steels are subject to legacy weld size requirements. These two factors result in widespread overwelding. Severe plate buckling in naval vessels has been attributed to oversized welds in thin plate ship structures. The problem of overwelding has two distinct sources: - The weld sizing method developed in the 1980s is still used in most shipbuilding specifications regardless of ship class. This prevents the incentive of application of latest technologies that can make strong, precision fillet welds for modern lightweight thin steel naval surface combatants. - Shipyard welders tend to make welds even larger than design requirement in order to satisfy Quality Assurance (QA) inspection. In a number of investigations, fillet welds requiring a leg size of 5mm are typically found to have an average size of 8mm, resulting in more than double the heat input and distortion. The approach to the solution of this overwelding problem will be described in detail in this paper: - Develop appropriate weld sizing criteria for thin plate structures-this can be facilitated by numerical modeling to ensure adequate static shear, tensile, bending, fatigue and dynamic impact capacity of structural welds; - Perform a robust designed experiment to confirm the models and establish confidence that precision weld sizes can provide necessary performance and strength throughout the design service life of the vessel.

Reduction of Overwelding and Distortion for Naval Surface Combatants, Part 1: Optimized Weld Sizing for Lightweight Ship Structures

2014 ◽  
Vol 30 (04) ◽  
pp. 184-193
Author(s):  
T. D. Huang ◽  
Michael Harbison ◽  
Lee Kvidahl ◽  
David Niolet ◽  
John Walks ◽  
...  
Keyword(s):  
High Strength ◽  
Ship Design ◽  
Rate Of Change ◽  
Construction Costs ◽  
Plate Structures ◽  
Shipbuilding Industry ◽  
Average Production ◽  
Thin Steel ◽  
Two Factors ◽  
Designed Experiment

As high-strength thin-steel use in ship design increases, dimensional management becomes critical to control construction costs and schedule in ship production. In the U.S. shipbuilding industry, improvements to shipbuilding facilities and processing technology have not kept pace with the rate of change in ship design. Additionally, new designs using thinner steels are subject to legacy weld-sizing criteria, which may inappropriately size welds on lightweight materials. These two factors result in widespread overwelding, causing severe plate buckling in naval vessels during construction. The problem of overwelding has two distinct sources:the weld-sizing methods developed in the 1980s are still used in most shipbuilding specifications regardless of ship class. This prevents the incentive of application of latest technologies that can make strong, precision fillet welds for modern lightweight thin steel naval surface combatants; andshipyard welders tend to make welds even larger than design requirements to satisfy naval production specifications, which do not allow for any undersized welds. On average, production welds are 3 mm larger than design, which can more than double the heat input and distortion caused by welding. The approach to the solution of this overwelding problem will be described in detail in this article:develop appropriate weld-sizing criteria for thin plate structures; this can be facilitated by numerical modeling to ensure adequate static shear, tensile, bending, fatigue, and dynamic impact capacity of structural welds; andperform a robust designed experiment to establish confidence that small weld sizes can provide necessary performance and strength to meet the design service life of the vessel and provide data to NAVSEA technical warrant holders to support the implementation of an underweld tolerance for ship production to prevent overwelding.

The Quadrimaran Reexamined

2015 ◽  
Author(s):  
William A. Hockberger
Keyword(s):  
High Performance ◽  
Early Stage ◽  
Ship Design ◽  
Technical Problems ◽  
Additional Information ◽  
Marine Vehicles ◽  
Detail Design ◽  
Marine Industry ◽  
And Performance ◽  
Met Expectations

The Quadrimaran was invented in France in the mid-1980s by Daniel Tollet. It was an inspired design and a radical departure from traditional ship design by a man from outside the marine industry unconstrained by industry technical practices and education. Technical experts could see it would entail more structure and subsystems than other high-performance vessels, but its promise was that those penalties would be more than offset by its claimed low power and fuel consumption. A prototype/demonstrator, Alexander, was built in 1990 and operated for five years carrying and impressing many hundreds of riders. Alexander performed beautifully and appeared to bear out what was claimed. Contracts for several Quadrimarans of different sizes came quickly, especially considering how conservative an industry this is. That was significantly due to Tollet's personal charisma and skill in selling riders on the dream of carrying passengers and freight over the water fast and in comfort, yet economically. Great skepticism prevailed in some quarters, especially among naval architects knowledgeable about AMVs (advanced marine vehicles) and early-stage whole-ship design. At technical meetings, one Quadrimaran principal would comment, for example, "Why would you carry freight across the Atlantic at 38 knots on 230,000 horsepower (a reference to the planned Fastship Atlantic TG-770) when you could do it at 60 knots on only 65,000 horsepower?" Listeners would ask how this could be possible, and he would assert again that the Quadrimaran could do it, but would decline to explain. Respected technical people were working with Tollet and his company and becoming convinced of the Quadrimaran's merit. Along with the contracts came engineers with experience in ship detail design and construction (very different from early-stage whole-ship design), or responsibilities for assessing and approving ships for service. Others were with engine and equipment suppliers. Their opinion that there was something unique and special about the Quadrimaran gave it credibility and influenced more people to accept the major claims made for it. Some dismissed the most extreme claims but still accepted the idea that the Quadrimaran was capable of unusually high performance - considerably less than was being claimed, perhaps, but high nevertheless. In hindsight it is clear the skeptics were right. Results never met expectations, nor could they have. In reality, the Quadrimaran has aspects that inherently prevent it from achieving the characteristics and performance its inventor believed attainable. It cannot be built in a commercially useful size and actually perform as intended. Why this is so will be explained. A crucial fact in the Quadrimaran's history is that Daniel Tollet and his close associates believed strongly that naval architects and engineers who had been immersed in working with the existing ship types would be unable to give the Quadrimaran the very different treatment they believed it required. (Their own educations and professional work were nontechnical.) Such people were excluded from the development of Quadrimaran designs, and the belated discovery of many fundamental technical problems can be attributed to this. The company Tollet established had a number of names over the years, and other associated entities were created at times for various purposes. In this paper they are referred to collectively as QIH (Quadrimaran International Holdings) so as not to confuse things unnecessarily. In 2004 QuadTech Marine LLC was established and acquired the Quadrimaran patent (US Patent No. 5,191,849) and related intellectual property from QIH. QuadTech laid out an extensive R&D program to close gaps in the technical background and address identified issues. In the process, additional information on earlier QIH projects and products was obtained and studied, which brought to light problems that significantly compromised the Quadrimaran's prospective performance and utility. The resulting much-reduced set of potential uses and users led the company to effectively stop pursuing Quadrimaran projects after 2009. (Note: The author was Chief Technology Officer for QuadTech Marine during 2006-9, studying the Quadrimaran and planning the R&D.)

Damage Detection with Piezoceramic Actuators in Thin Steel Structures

2008 ◽  
Vol 15 (3-4) ◽  
pp. 269-275 ◽  
Author(s):  
Dieter Dinkler ◽  
Ursula Kowalsky ◽  
Konrad Schuster
Keyword(s):  
Damage Detection ◽  
Steel Structures ◽  
Thin Steel

scholarly journals A Study into the Validity of the Ship Design Spiral in Early Stage Ship Design

2017 ◽  
Vol 33 (02) ◽  
pp. 81-100
Author(s):  
Rachel Pawling ◽  
Victoria Percival ◽  
David Andrews
Keyword(s):  
Design Process ◽  
Early Stage ◽  
Ship Design ◽  
Complex Process ◽  
University College London ◽  
The University ◽  
Convenient Model ◽  
Balanced Solution ◽  
Block Approach ◽  
Design Spiral

For many years, the design spiral has been seen to be a convenient model of an acknowledged complex process. It has virtues particularly in recognizing the ship design interactive and, hopefully, converging nature of the process. However, many find it unsatisfactory. One early criticism focused on its apparent assumption of a relatively smooth process to a balanced solution implied by most ship concept algorithms. The paper draws on a postgraduate design investigation using the University College London Design Building Block approach, which looked specifically at a nascent naval combatant design and the issues of size associated with "passing decks" and margins. Results from the study are seen to suggest that there are distinct regions of cliffs and plateau in plots of capability against design output, namely ship size and cost. These findings are discussed with regard to the insight they provide into the nature of such ship designs and different ways of representing the ship design process. The paper concludes that the ship design spiral is a misleading and unreliable representation of complex ship design at both the strategic and detailed iterative levels.

Design of Transverse Fillet Welds in the Lapped Joints of Thin Steel Plates

2018 ◽  
Vol 18 (1) ◽  
pp. 337-348
Author(s):  
Shahabeddin Torabian ◽  
Feng Xiao ◽  
Richard B. Haws ◽  
Benjamin W. Schafer
Keyword(s):  
Steel Plates ◽  
Fillet Welds ◽  
Thin Steel

Engineering and Production Technology for Lightweight Ship Structures, Part II: Distortion Mitigation Technique and Implementation

2007 ◽  
Vol 23 (02) ◽  
pp. 82-93 ◽  
Author(s):  
T. D. Huang ◽  
C. Conrardy ◽  
P. Dong ◽  
P. Keene ◽  
L. Kvidahl ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Steel Structures ◽  
Critical Parameters ◽  
Battelle Memorial Institute ◽  
Functional Requirements ◽  
Ship Structures ◽  
Distortion Control ◽  
Us Navy ◽  
Thin Steel ◽  
Buckling Distortion

Shipboard applications of lightweight structures have increased over recent years in both military and commercial vessels. Thin steel reduces topside weight, enhances mission capability, and improves performance and vessel stability, but the propensity of buckling distortion has increased significantly. At present, several US Navy construction programs are experiencing high rates of buckling distortion on thin steel structures. The standard shipyard practice of fabricating stiffened steel panels by arc welding is one of the major contributors to this distortion. Correcting the distortion is a necessary but time-consuming operation that adds no value and ultimately tends to degrade the quality of the ship structure. With a major initiative funded by the US Navy, Northrop Grumman Ship Systems (NGSS) has undertaken a comprehensive assessment of lightweight structure fabrication technology since 2002. Through collaborative research, significant progress has been achieved in the development of distortion-control techniques. Reverse arching, transient thermal tensioning (TTT), stiffener assembly sequencing, and other preferred manufacturing techniques were developed at NGSS to reduce distortion and eliminate the high rework costs associated with correcting that distortion. Complex lightweight panel structures, which are reinforced by long slender stiffeners along with numerous cutouts and inserts, pose a major challenge for distortion control. The geometric complexity yields a more complicated buckling behavior, which drives the need to develop a more fine-tuned finite element model to determine critical parameters and heating patterns for the TTT process. NGSS has recently teamed with Edison Welding Institute (EWI), Battelle Memorial Institute, and the University of New Orleans on a Navy project to further refine TTT procedures for complex lightweight ship structures. In this paper, functional requirements and the design of TTT process and production equipment are discussed. The refined TTT process will be benchmarked by the test panel observations, and a laser scanning device, LIDAR, will be used to analyze panel distortion topography.

Rancang Bangun Alat Sentrigufal Pencuci Daging Buah Kelapa Menggunakan Cairan Air Kelapa (Pre-Processing Metode Sentrifugasi)

Jurnal METRIS ◽  
2020 ◽  
Vol 21 (01) ◽  
pp. 31-36
Author(s):  
Hadi Santosa ◽  
Yuliati . ◽  
Ig. Jaka Mulyana
Keyword(s):  
Early Stage ◽  
Economic Value ◽  
Coconut Oil ◽  
Coconut Water ◽  
Raw Material ◽  
Virgin Coconut Oil ◽  
Process Technology ◽  
Washing Process ◽  
Pressure Nozzle ◽  
Coconut Meat

The diversification of the coconut processing industry into Virgin Coconut Oil (VCO) as a more prospective coconut derivative is currently still growing rapidly. VCO is a virgin coconut oil product that is beneficial for health, and can be used as a raw material for natural cosmetics which has high economic value. Preliminary research has successfully designed the construction of a coconut husk peeler and a coconut shell breaker machine as an early stage in the VCO production process technology. The discussion of this paper covers the design of a coconut meat washing machine utilizing coconut water which consists of a rotating tube with an adjustable tube rotation speed with an inverter and an electric motor as the driving force equipped with a high pressure nozzle with ± 75 psi pressure. Inside the tube there is a retaining divider that regulates the flow of the washed coconut meat. The washing process uses coconut water to wash coconut meat in a washing tube that rotates at a certain speed as needed with a capacity of 8 kg timer for ± 3-5 minutes. Coconut water is drained and coconut meat is ready for the next process.

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