AFRY AB (publ) is a Swedish-Finnish supplier of engineering, design, and advisory services, with a global reach. The company originates from Sweden and it was formed in 1895 under the name of “The Southern Swedish Steam Generator Association” (in Swedish: Södra Sveriges Ångpanneförening). AFRY has today 17,000 experts in infrastructure, industry, energy and digitalisation all around the world..
In this paper we describe the results of a study on the design of open and co-opetitive systems of systems for mobility. A system of systems (SoS) is a set of independent systems (CS – Constituent Systems) that interact to create capabilities that none of the constituent systems can accomplish on their own. A CS can be simultaneously part of several SoS. The independence of the constituent systems is an important and central ingredient in an SoS, and is often divided into managerial and operational independence. We argue that the mobility SoS of the future can benefit from being open and co-opetitive (i.e., simultaneously collaborating and competing) to enable combined mobility (MaaS) for real. If competition between CS is not allowed, new entrants will choose to compete with the SoS instead of becoming part of it. If a new entrant develops much better vehicles or better ways to find transport solutions for users, that entrant must be able to become part of the SoS and take market share from other actors.
Concrete, as a complex and anisotropic material, poses challenges in accurately simulating its behavior in numerical simulations. This paper focuses on selecting an appropriate constitutive model for simulating the behavior of a steel–concrete composite column using finite element analysis under compression and push-out tests. Two models are analyzed and compared, namely, Drucker–Prager and concrete damage plasticity. The results demonstrate that the concrete damage plasticity model outperforms the Drucker–Prager model in all six test cases, indicating its superior accuracy in capturing the composite column’s behavior. This study enhances the reliability of numerical simulations for steel–concrete composite structures by choosing the most suitable constitutive model, parallel with extensive sensitivity analysis and model calibration. The findings emphasize the significance of meticulous model selection and precise parameter definition for achieving accurate predictions of concrete behavior. This research contributes to advancing the understanding and modeling of concrete’s intricate behavior in structural analyses.
Welding of rails in the field is usually associated with a large heat input, which results in a large heat-affected zone (HAZ), which in turn may impair the welded rail head and decrease its service life. An innovative orbital friction welding (OFW) process with an intermediate eccentrically oscillating disk is proposed, and a demonstrator has been constructed. This enables welding of rails, which have a non-symmetric cross-sectional area and must be stationary during welding. The process is characterized by low heat input, creating a narrow HAZ, and low welding deformations. A thermo-mechanical finite element model is developed to determine suitable process parameters to create a narrow HAZ. A phenomenological model for heat generation during friction welding is developed for pearlitic rail steel with parameters calibrated from rotary friction welding experiments on pipes. The temperature dependence of the friction coefficient in the interface is established. Pilot tests with the demonstrator OFW machine on bars with a quadratic cross section showed that preheating will be required to guarantee a fully pearlitic weld zone. This was verified by the simulations of the thermo-mechanical finite element model.
