Size and geometry effects in notched compact tension specimens. (July 2017)

• Record Type: Journal Article
• Authors: Horn, A.J.; Sherry, A.H.; Budden, P.J.
• Is Part Of: International journal of pressure vessels and piping. Volume 154(2017)
• Page Start: 29
• Page End: 40
• Publication Date: 2017-07
• Subjects: Blunt notch -- Effective fracture toughness -- Notch failure assessment diagram; Pressure vessels -- Periodicals; Pipe -- Periodicals; Récipients sous pression -- Périodiques; Tuyaux -- Périodiques; Pipe; Pressure vessels; Periodicals; 681.76041
• DOI: 10.1016/j.ijpvp.2017.05.012
• Languages: English
• ISSNs: 0308-0161

Abstract

Abstract: This paper uses Weibull stress analysis to investigate whether the effective notch toughness K m a t ρ for cleavage fracture measured using Compact Tension (CT) specimens containing a U-notch is dependent on the size and geometry of the CT specimen. Notched CT specimens are typically used to measure a material's effective notch toughness K m a t ρ and to assess failure of a structure containing a non-sharp defect using the Notch Failure Assessment Diagram (NFAD). The paper concludes that K m a t ρ is dependent on specimen thickness B over and above the microstructural weakest link effect arising from differences in the volume of the plastic zone; K m a t ρ is a function of not only the in-plane effect of the notch radius but also an out-of-plane constraint loss which itself is enhanced by the presence of the notch radius. This out-of-plane constraint loss can be more significant than the in-plane effect of the notch radius. The use of experimentally measured K m a t ρ values in an NFAD assessment of a notched structure may therefore be non-conservative if the out-of-plane constraint loss in the CT specimen is more significant than in the structure. For the material considered in this paper, doubling the thickness B of the CT specimen resulted in plane strain conditions being sufficiently dominant to eliminate out-of-plane constraint loss in the CT specimen. Abstract : Effective notch toughness is dependent on both notch radius and specimen thickness. Thickness effect can be more significant than the in-plane effect of notch radius. Failure predictions may be non-conservative if thickness effects not accounted for.