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Experimental and numerical investigation on specimen geometry effect on the ctod value for VL-E36 shipbuilding steel

100%

Kowalski J.

tom nr 3

110--116

There are special cases in the marine industry, where additional material tests, such as the fracture toughness test, must be performed. Additional fracture toughness tests, such as CTOD (Crack Tip Opening Displacement), are typically performed on three-point bend specimens. The dimension that defines all the specimen dimensions is the thickness of the material to be tested. It is recommended by classification societies (e.g. DNVGL) to test specimens that are twice as high as the material thickness. The width determines the length and, therefore, the weight of the specimen which, for a 100 mm plate is over 140 kg. Current ASTM E1820, BS7448-1 and ISO 12135 testing standards also allow for proportions other than those recommended. This results in a much smaller test piece. Reducing the specimen size allows the testing machine to achieve lower forces than a specimen with a width to thickness ratio of two. This paper presents the effect of changing the specimen geometry on CTOD test results. Research was performed for specimens with a height to thickness ratio of one and two. Abaqus software was used for numerical calculations. The numerical results were, at selected points, verified experimentally.

Numerical analysis of the influence of in-plane constraints on the crack tip opening displacement for SEN(B) specimens under predominantly plane strain conditions

72%

Graba M.

2016

tom Vol. 21, no. 4

849--866

This paper presents a numerical analysis of the relationship between in-plane constraints and the crack tip opening displacement (CTOD) for single-edge notched bend (SEN(B)) specimens under predominantly plane strain conditions. It provides details of the numerical model and discusses the influence of external load and in-plane constraints on the CTOD. The work also reviews methods for determining the CTOD. The new formula proposed in this paper can be used to estimate the value of the coefficient dn as a function of the relative crack length, the strain hardening exponent and the yield strength - dn(n, σ0/E, a/W), with these parameters affecting the level of in-plane constraints. Some of the numerical results were approximated using simple mathematical formulae.

A numerical analysis of selected elastic-plastic fracture parameters for DEN(T) plates under plane strain conditions

58%

Graba M.

2017

tom Vol. 22, no. 1

49--80

This paper provides a numerical analysis of selected parameters of fracture mechanics for double-edge notched specimens in tension, DEN(T), under plane strain conditions. The analysis was performed using the elastic-plastic material model. The study involved determining the stress distribution near the crack tip for both small and large deformations. The limit load solution was verified. The J-integral, the crack tip opening displacement, and the load line displacement were determined using the numerical method to propose the new hybrid solutions for calculating these parameters. The investigations also aimed to identify the influence of the plate geometry and the material characteristics on the parameters under consideration. This paper is a continuation of the author’s previous studies and simulations in the field of elastic-plastic fracture mechanics.

Krytyczne podejście inżynierskie w budowie rurociągów magistralnych

58%

Sędek P.

tom nr 1

81--83

W artykule opisano przykład zastosowania krytycznego podejścia inżynierskiego (ECA) w ocenie kryteriów jakościowych dla przykładowego rurociągu przesyłowego na gaz ziemny. Porównano wymiary niezgodności krytycznych wyliczonych wg procedur ECA z wymaganiami wg normy PN-ISO 5817. Łagodniejsze wymagania wynikające z ECA umożliwiają znaczne zmniejszenie zakresu prac naprawczych w budowie rurociągów, co wiąże się z obniżeniem kosztów.

The article describes an example use case of the engineering critical assessment (ECA) in assessing the quality criteria for a natural gas transmission pipeline. The critical defect dimensions calculated according to the ECA procedures have been compared to the requirements of PN-ISO 5817. More flexible requirements as described in the ECA make it possible to significantly minimize the scope of repair works in the pipeline construction, therefore reducing costs.