One of the main requirements of threaded & coupled connections used in oil-producing wells is the ability to resist high tensile loads. In order to ensure integrity under ever-increasing loads, the geometric parameters of the connection can be modified. In this paper, an FEA study of a 4.5 inch casing connection is reported to examine the effects of a modified load angle in combination with high tensile forces. The focus is on two failure mechanisms: jump-out and plastically deformed zones. Furthermore, a relative motion of pin and box at the contact regions is observed. It is concluded that using a negative load flank might be beneficial in order to prevent jump-out. At the same time, the deformations at the roots of the last engaged threads of the pin appear to be larger and relative sliding increases. Despite an optimization against one failure mechanism, the connection might fail as a result of an inevitable reduction of resistance against another.Keywords: threaded connection; casing; modified load angle; failure mechanisms INTRODUCTIONThreaded pipe connections are widely used in the oil and gas industry for well completion, drill strings and risers in offshore applications [1]. When comparing the nature of threaded connections with welded connections, major advantages can be identified. On one hand, the limited time which is required to connect two pipes in the field reduces the time to complete wells drastically. On the other hand, it is possible to break up the threaded joints without causing excessive plastic deformations. The ability to reuse the pipes in other wells is of vital importance for drill pipes.Due to the introduction of high performance connections which are characterized by a unique geometry consisting of a metal-to-metal seal, torque shoulder and thread profile[2], companies are able to build deeper wells in more extreme conditions. When taking into account the increased depths and hostile environmental effects, different failure mechanisms have to be examined in order to optimise the threaded joint.In this study, two frequently occurring types of failure are being examined. Drilling deeper wells results in the use of longer casing and drill strings, which implies an increase of weight leading to higher axial loads. These axial forces can cause the threaded joints to separate due to a phenomenon known as jump-out [3]. In order to reuse the connections when applied in drill strings, one of the prerequisites dictates that plastic deformation is non-existent or very limited. For this reason, the axial plastic strains within the threads can be used as the basis of a criterion to quantify the plasticity occurring in the connection.A numerical study on a 4.5 inch threaded-and-coupled connection (T&C) with standard API buttress threads and one with buttress threads with modified load angle subjected to an axial tensile load is carried out and a comparison is made. As a result, an indication of which failure mechanism is more likely to occur becomes visible.Sustainable Construction and De...

Orthogonal cutting is probably the most studied machining operation for metals. Its simulation with theFinite Element Analysis (FEA) method is of paramount academic interest. 2D models, and to a lesserextent 3D models, have been developed to predict cutting forces, chip formation, heat generation andtemperature fields, residual stress distribution and tool wear. This paper first presents a brief review ofscientific literature with focus on FEA modelling of the orthogonal cutting process for steels. Following,emphasis is put on the building blocks of the simulation model, such as the formulation of the mechanicalproblem, the material constitutive model, the friction models and damage laws