Mats Näsström

Simulation of multipass welding of a thick plate

Multipass butt welding of a very thick steel plate has been performed. Transient temperatures and residual stresses have been measured. The agreement between calculations and experiments is good. T ...

Finite element simulation and measurement of welding residual stresses

Residual strains and stresses in a hollow steel beam that had been welded to a D-shaped cross-section have been simulated by plane deformation finite element models and compared with experimental measurements obtained using the neutron diffraction strain-scanning technique. Neutron strain scanning, in contrast to other experimental techniques, is capable of measuring, accurately, non-destructively and in detail, the internal strain state at selected locations and directions within a component. This makes it a preferred method for validating model calculations of strain and stress distributions in components. In the finite element simulations a plane deformation model incorporating temperature-dependent material properties was adopted. With the assumptions for material properties that were made, the plane deformation model predicts the overall bending of the beam and the overall residual strains and stresses reasonably well. Locally, in the weld metal the predicted residual strains and stresses depend very much on the values of the thermal strain, which in one simulation include volume changes due to solid-state phase transformations. In the other simulation presented here the volume changes due to solid-state phase transformations were not accounted for.

Simulation of hot isostatic pressing of metal powder components to near net shape

Presents a finite element formulation of hot isostatic pressing (HIP) based on a continuum approach using thermal‐elastoviscoplastic constitutive equations with compressibility. The formulation takes into consideration dependence of the viscoplastic part on the porosity. Also takes into account the thermomechanical response, including nonlinear effects in both the thermal and mechanical analyses. Implements the material model in an implicit finite element code. Presents experimental procedures for evaluating the inelastic behaviour of metal powders during densification and experimental data. Chooses the simulation of the dilatometer measurement of a cylindrical component during HIP and manufacturing simulation of a turbine component to near net shape (NNS) as a demonstrator example. Both components are made of a hot isostatically pressed hot‐working martensitic steel. Compares the result of the simulation in the form of the final geometry of the container with the geometry of a real component produced by HIP. Makes a comparison between the calculated and measured deformations during the HIP process for the cylindrical component. Measures the final geometry of the turbine component by means of a computer controlled measuring machine (CMM). Performs the complete process from design and simulation to geometry verification within a computer‐aided concurrent engineering (CACE) system.

Supporting engineering decisions through contextual, model-oriented communication and knowledge-based engineering in simulation-driven product development: an automotive case study

Modern manufacturers rely increasingly on overlapping activities and frequent, bilateral exchange of preliminary information, adding to the complexity of information exchange and general reuse. The approach presented in this paper relies on a reuse process, embedded in the design environment already used, to avoid disrupting the design process and to increase the foundation upon which decisions are made. The proposed approach relies on knowledge-based extensions to commercial CAE systems and 3D CAE models to enable and ensure simulation-driven design capabilities and contextual communication within the early stages of product development. The approach has been shown to increase the simulation-driven capabilities in a business-to-business scenario, and in extension, increase the foundation upon which decisions are made and the likelihood of reaching a feasible and optimal final design. In conclusion, a simulation-driven design approach to product development has to be more than enabled to truly make a difference in the development process. Investigation and evaluations show that supporting tools and relevant information must be made readily available, intuitive, integrated into the environment where they are needed and, ultimately, be perceived as a natural part of daily development in order for them to be accepted and used.

A PROPOSED METHOD TO PRESERVE KNOWLEDGE AND INFORMATION BY USE OF KNOWLEDGE ENABLED ENGINEERING

Today’s automotive industry produces more new car models in a shorter time than ever before. Every car model comes in many different versions regarding number of doors, engine, transmission etc while being built on a platform strategy. This leads to a lot of different knowledge and information that needs to be tracked for the different components in addition to other information e.g. what function does design features have, why is this radius not smaller etc. Volvo Car Corporation (VCC) is in need of an effective method to save and present all this knowledge and information today. This paper describes a new method, to gather and save knowledge and information about car body parts also called body-in white, which was implemented in a demonstrator and tested and evaluated on VCC.Copyright

Combined Solid and Shell Element Modelling of Welding

Finite element calculations of residual stress distribution in a welded component from a hollow square section inconel tube are presented in this paper, figure 1. Shell element can be successfully used in finite element calculations of thin walled structures [1]. However, in the weld and the heat affected zone (HAZ) shell elements may not be sufficient, since the through thickness stress gradient is high in these regions. In the study presented here a combination of eight-nodes solid elements and four-nodes shell elements is used. The solid elements are used in and near the weld and shell elements are used elsewhere. This combination of solid elements and shell elements reduces the number of degrees of freedom in the problem in comparison with the use of solid elements only.

Accuracy In Thermal Analysis Of Laser Welding

The paper focus on the problem of obtaining accurate thermal fields despite the uncertainty of the thermal heat input and thermal properties at high temperatures. The net heat input is the primary factor for obtaining an accurate temperature field. A good correlation between simulations and experiments is obtained. The net heat input during laser welding a bead on a thin plate made of an austenitic stainless steel is determined using a water calorimeter. Transient temperature is measured by thermocouples. The finite element method is used in the numerical simulation of the process.

Efficient design module capture and representation for product family reuse

New business models and more integrated product development processes require designers to make use of knowledge more efficiently. Capture and reuse are means of coping, but support, techniques, and mechanisms have yet to be sufficiently addressed. This paper consequently explores how computer-aided technologies (CAx) and a computer-aided design (CAD) model-oriented approach can be used to improve the efficiency of design module capture and representation for product family reuse. The first contribution of this paper is the investigation performed at a Swedish manufacturing company and a set of identified challenges related to design capture and representation for reuse in product family development. The second contribution is a demonstrated and evaluated set of systems and tools, which exemplifies how these challenges can be approached. Efficient design capture is achieved by a combination of automated and simplified design capture, derived from the design implementation (CAD model definition) to the extent possible. Different design representations can then be accessed by the designer using the CAD-internal tool interface. A web application is an example of more generalpurpose representation to tailor design content, all of which is managed by a product lifecycle management (PLM) system. Design capture is based on a modular view block definition, stored in formal information models, management by a PLM system, for consistent and reliable design content. It was, however, introduced to support the rich and expressive forms of capture and representation required to facilitate understanding, use, and reuse of varied and increasingly complex designs. A key element in being able to describe a complex design and its implementation has been capture and representation of a set of design states. The solution has been demonstrated to effectively be able to capture and represent significant portions of a step-by-step design training material and the implementation of complex design module through a set of design decisions taken. The validity and relevance of the proposed solution is strengthened by the level of acceptance and perceived value from experienced users, together with the fact that the company is implementing parts of it today.

Integrated Capture and Representation of Product Information In Computer-Aided Product Development

This paper features the implementation and evaluation of a proposed approach for information capture and representation integrated into the existing design environments at two manufacturing companies. A tool has been developed that automatically derives information from the CAD system during design and provides users with the means to capture product information that has previously been documented outside of the CAD system. Product information is managed in a PLM data model and becomes, once stored, the foundation for providing tailored views of information.Feedback from the evaluation shows that the prescribed approach was preferred to the current one and that it would likely provide value to users, both authors and consumers, of product information. This approach can reduce the time required to capture the pertinent product information. However, the primary savings are likely to be indirect as a result of increased consistency, understanding, and the potential (re)use of product information.The approach and tools presented constitute another step toward providing each stakeholder with more efficient, intuitive, contextual, and purposeful support for information capture and representation in computer-aided product development.Copyright

An Empirical Study of Information Exchange and Design Support in Product Family Development

An investigation carried out at a Swedish manufacturing company has focused specifically on information exchange and design support in and between activities in the company’s product family development process. The process allows, within a defined product family, automated generation of 3D models, product specifications, and a complete foundation for subsequent manufacture and verification.The core contributions of this paper are the investigation performed, a set of identified challenges which relate to the complexity of everyday decisions made in product family development, how these challenges can be approached and a set of tools exemplifying that approach.The study indicates that there are limitations in terms of motivation, resources and support for insight, understanding and consequent consideration to downstream implications of design decisions made. The question is whether tools and methods, which are integral aspects of the process already, might serve to further illuminate the process, maximize purposeful support and thereby minimize the efforts required to better consider downstream implications of decisions made. It is the opinion of the authors that it can, and the set of tools for information exchange and design support presented in this paper serves to exemplify how.Copyright