Searched for: author%3A%22Walters%2C+C.L.%22
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Walters, C.L. (author), Alvaro, A. (author), Maljaars, J. (author)
The Fatigue Ductile–Brittle Transition (FDBT) is a phenomenon similar to the fracture ductile to brittle transition, in which the fracture mode of the fatigue cracks changes from ductile transgranular to cleavage and/or grain boundary separation. Fatigue at temperatures below the FDBT has a much different crack growth rate than fatigue above...
article 2016
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Dekker, R. (author), Walters, C.L. (author)
Localised buckles can occur in crasheswhen compressive stresses are dominant. However, due to their local appearance, they might be overlooked by a finite element analysis, meaning that local failure due to bucklingwill not be predicted. This could, for example, be catastrophic in the case of the crushing of a fuel tank or the impact on a ship...
article 2016
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Atli-Veltin, B. (author), Dekker, R. (author), Brunner, S.K. (author), Walters, C.L. (author)
Depending on the state of stress, material can fait in a number of different modes during a collision. Three modes are identified here as material separation in the absence of necking, material separation after the onset of necking, and localized buckling/wrinkling. Through a series of case studies, the states of stress present in a collision...
conference paper 2016
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Dekker, R. (author), Walters, C.L. (author)
Localized buckles can occur in crashes when compressive stresses are dominant. However, due to their local appearance, they might be overlooked by a finite element analysis, meaning that local failure due to buckling will not be predicted. This could, for example, be catastrophic in the case of the crushing of a fuel tank or the impact on a ship...
conference paper 2016
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Walters, C.L. (author), Dragt, R.C. (author)
Current codes and norms allow for structures to be operated in the transition between ductile and brittle behavior. Further, they often treat the Ductile to Brittle Transition Temperature as a constant even though it is well known to depend on a variety of factors, such as loading rate, constraint, and prior cold deformation. This paper roposes...
conference paper 2016
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Tang, L. (author), Walters, C.L. (author), van den Heuvel, W. (author), van Daelen, E.C.M. (author)
Failure prediction in crash analyses of ships has traditionally made use of an equation that relates the failure strain to the gage length and material thickness. The equation is derived based on the idea that a neck ( a localization of strain) is a fixed size relative to the thickness and that it can be homogenized over a larger gage section....
conference paper 2015
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Dragt, R.C. (author), Kraus, J. (author), Walters, C.L. (author)
Simulation of failure in thin-walled structures is critical for the correct determination of crash performance of ships and offshore structures. Typically, shell elements are used, but these elements are not able to adequately capture local failure, especially inside of a neck. This paper addresses these gaps by adapting the Bridgman (1952)...
conference paper 2015
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Hauge, M. (author), Maier, M. (author), Walters, C.L. (author), Ostby, E. (author), Kordonets, S.M. (author), Zanfir, C. (author), Osvoll, H. (author)
An ISO subcommittee was set up in 2011 to improve the existing standards and norms with respect to arctic offshore operations for the petroleum, petrochemical, and natural gas industries. Within this subcommittee, a specific working group was established to address the application of materials in the environment of the arctic and cold regions....
conference paper 2015
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Walters, C.L. (author), Przydatek, J. (author)
It is vely well-known that fracture toughness depends on loading rate. Higher strain rates can shift the ductile to brittle transition curve to higher temperatures, resulting in a more brittle structure at the same temperature. However, there is little effort to relate the testing rate to the loading rate within the offshore and maritime...
conference paper 2014
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Walters, C.L. (author)
Simulation of failure in plate materials (represented as shell elements) is critical for the correct determination of crash performance of ships and offshore structures. This need has traditionally been filled with failure loci that give the failure strain in terms of stress triaxiality. In recent years, a third dimension (Lode parameter) has...
conference paper 2014
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Walters, C.L. (author)
It is well-known that for fracture, ferritic steels undergo a sudden transition from ductile behavior at higher temperatures to brittle cleavage failure at lower temperatures. However, this phenomenon has not received much attention in the literature on fatigue. The so-called Fatigue Ductile-Brittle Transition (FDBT) has been identified in the...
article 2014
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Voormeeren, L.O. (author), Tang, L. (author), Walters, C.L. (author), Vredeveldt, A.W. (author)
Crash analysis in the maritime and offshore industry typically relies on failure criteria that are based only on uniaxial states of stress. However, it is well known that the failure strain depends on the state of stress, and the state of stress in ship collisions is not necessarily uniaxial. Although more detailed failure models are routine in...
conference paper 2014
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Walters, C.L. (author)
public lecture 2014
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Walters, C.L. (author), Dragt, R.C. (author), Romeijn, E. (author), van der Weijde, G.D. (author)
In this paper, the applicability of currently-available S355 and S690 steels to Arctic applications is estimated according to current classification rules. A database of results used for quality control for offshore structures that were not necessarily designed for Arctic operations was analyzed. The results needed to be extrapolated to lower...
conference paper 2014
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Tang, L. (author), Walters, C.L. (author)
Cleavage fracture of steel is governed by micromechanical mechanisms, but it is modelled with simple continuumlevel models. These models are starting to reach the limits of their applicability, so there is interest to look deeper into micromechanical modelling of fracture processes. In order to model fracture on the microstructural level, a...
article 2014
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Walters, C.L. (author), Voormeeren, L.O. (author)
conference paper 2014
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Walters, C.L. (author), van der Weijde, G.D. (author)
A low-cost variation of CTOD testing is proposed. This variation follows BS7448, but has several nonstandard deviations, including: • Using a fixed notch width of 0.5 mm. • Using fatigue pre-cracks that are shorter than normal requirements to save the associated expense. • Using Single Edge Notched 3-point Bending (SENB) specimens with cross...
conference paper 2013
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Walters, C.L. (author)
The current paper provides a procedure for adjusting the failure strain of shell elements based on both mesh size and stress triaxiality. This procedure is a general framework that gives a homogenisation of a neck over the entire length of an element and it uses an arbitrary forming limit diagram (FLD) and stress triaxiality-based failure...
article 2013
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Walters, C.L. (author), Voormeeren, L.O. (author)
The minimum pre-crack necessary to achieve an accurate measurement of the J-integral is examined with the use of elastic-plastic finite element analysis. This minimum pre-crack is shorter than what is specified in fracture codes ASTM E1820 and BS 7448. A variety of steel properties are considered, but the focus is on S690 grade steel. Testing a...
conference paper 2013
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Walters, C.L. (author), Voormeeren, L.O. (author), Janssen, M. (author)
In determining the fracture toughness of a test specimen, standards currently require either locally-measured load-line displacements or clip gage displacements. In order to measure these parameters, secondary sensors generally need to be installed and calibrated, which often comes at a higher cost. As crosshead displacements are automatically...
conference paper 2013
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