Papers by Keyword: Brittle Failure

Abstract: This paper presents 25 new experimental results from gray cast iron notched specimens tested under torsion loading. V-notch (with an opening angle of 120°) is considered with a root radius ranging from 0.1 to 2.0 mm. Plots of torque loads versus twist angles are recorded varying the notch root radius. Such results can help in evaluating numerical and theoretical models of the fracture of notched components under mode III loading. The second part of the paper deals with a discussion on the experimental results. A non-conventional application of the strain energy density is carried out showing a good agreement between experimental results and theoretical fracture assessments and it is used to justify the link between nominal and local fracture approaches.

Abstract: The brittle failure finite element method is widely used in arch dam safety evaluation, but it also has some problems, the concrete strength criterion is different, the dam failure range is different. This article first introduces brittle failure constitutive relation and three strength criterions, then takes a high arch dam as an example to compute, obtains some conclusions that the relative failure range of foundation plane corresponds to blaxial strength criterion is slightly bigger than the result of uniaxial strength criterion, is almost the same as the result of triaxial strength criterion. Because the influence of the third principal stress is compressed stress to the dam crack is taken into account under multiaxial strength criterion, therefore using multiaxial strength criterion is more reasonable.

Abstract: The current work is aimed at development of a numerical model able to describe complex damage phenomena that occur during an impact event in a sandwich structure having a honeycomb core. The complex material models employed within the research include linear-elastic and elasto-plastic material models having transverse isotropy as well as damage evolution models for both brittle failure and plastic failure. Within this paper remarks concerning the failure of the skins and core components as well as dissipated impact energy and affected regions are done.

Abstract: A 3D grain-level formulation for the study of brittle failure in polycrystalline microstructures is presented. The microstructure is represented as a Voronoi tessellation and the boundary element method is used to model each crystal of the aggregate. The continuity of the aggregate is enforced through suitable conditions at the intergranular interfaces. The grain-boundary model takes into account the onset and evolution of damage by means of an irreversible linear cohesive law, able to address mixed-mode failure conditions. Upon interface failure, a non-linear frictional contact analysis is introduced for addressing the contact between micro-crack surfaces. An incremental-iterative algorithm is used for tracking the micro-degradation and cracking evolution. A numerical test shows the capability of the formulation.

Abstract: A recent trend in the development of CO2 pipelines is the shift from the predominance of transport of CO2 for enhanced oil recovery (EOR) to the transportation of CO2 as part of the carbon capture and storage (CSS) process for global warming mitigation. Among the processes of capture, transport, and storage, less attention has been paid to transport as it is assumed to be for granted, existing technology. This paper presents a focused analysis of the problem of structural integrity of CO2 pipelines through reviewing the state-of-the-art literature and practice, and highlights the need for a unified code of practice for the modelling of integrity and, due to the potentially hazardous nature of CO2, safety, in these pipelines.

Abstract: It is clear from the former researches on reinforced concrete filled tubular steel (RCFT) structures that RCFT structures have better performance than concrete filled tubular steel (CFT) structures, in other words, because of the existence of reinforcement, the performance of RCFT differed from that of CFT. Therefore, to clarify the effect of axial reinforcement on mechanical properties of RCFT, compression tests of RCFT columns with different ratio of axial reinforcement were carried out, meanwhile, corresponding tests of CFT, reinforced concrete (RC), pure concrete, and steel tube columns were done to compare with RCFT. By a series of comparison and analysis, effect of axial reinforcement on RCFT columns were discussed, and following conclusions were drawn: reinforcement ratio has direct effect on performance of RCFT. Over arranged reinforcement will cause pre-failure of concrete without exerting strength of reinforcement, and not only may cause brittle-failure or lower performance of the structure, but also cause the increase of construction cost. On the contrary, proper ratio of reinforcement can make the RCFT possess better confined effect, improve overall performance of the RCFT structure; furthermore, whatever the ratio of reinforcement, RCFT has better performance than both CFT and RC, especially possesses more brittle-failure resistance than CFT.

Abstract: The use of high-strength composites in the reinforcement of structural timber has been documented to enhance the strength and stiffness of wood structural members. Global reinforcement is applied over the entire surface of the reinforced member. Local reinforcement is a targeted strengthening of highly-stressed zones susceptible to failure. Both types of reinforcement enhance the capacity of the reinforced members and mitigate brittle failure modes. This paper presents an overview of the application of fiber-based composites in the reinforcement of beams, columns and connections of timber structures and discusses the state-of-the-art technologies in reinforcement. The applications are illustrated on the reinforcement of beams, arches, frames and beam-to-column connections.