| 1. |
- Johansson, Karl-Axel, et al.
(author)
-
The quality assurance process for the ARTSCAN head and neck study - a practical interactive approach for QA in 3DCRT and IMRT.
- 2008
-
In: Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology. - : Elsevier BV. - 0167-8140 .- 1879-0887. ; 87:2, s. 290-9
-
Journal article (peer-reviewed)abstract
- AIM: This paper describes the quality assurance (QA) work performed in the Swedish multicenter ARTSCAN (Accelerated RadioTherapy of Squamous cell CArcinomas in the head and Neck) trial to guarantee high quality in a multicenter study which involved modern radiotherapy such as 3DCRT or IMRT. MATERIALS AND METHODS: The study was closed in June 2006 with 750 randomised patients. Radiation therapy-related data for every patient were sent by each participating centre to the QA office where all trial data were reviewed, analysed and stored. In case of any deviation from the protocol, an interactive process was started between the QA office and the local responsible clinician and/or physicist to increase the compliance to the protocol for future randomised patients. Meetings and workshops were held on a regular basis for discussions on various trial-related issues and for the QA office to report on updated results. RESULTS AND DISCUSSION: This review covers the 734 patients out of a total of 750 who had entered the study. Deviations early in the study were corrected so that the overall compliance to the protocol was very high. There were only negligible variations in doses and dose distributions to target volumes for each specific site and stage. The quality of the treatments was high. Furthermore, an extensive database of treatment parameters was accumulated for future dose-volume vs. endpoint evaluations. CONCLUSIONS: This comprehensive QA programme increased the probability to draw firm conclusions from our study and may serve as a concept for QA work in future radiotherapy trials where comparatively small effects are searched for in a heterogeneous tumour population.
|
|
| 2. |
- Lundkvist, Axel, et al.
(author)
-
A discrete element analysis of the mechanical behaviour of a lithium-ion battery electrode active layer
- 2023
-
In: Powder Technology. - : Elsevier BV. - 0032-5910 .- 1873-328X. ; 425
-
Journal article (peer-reviewed)abstract
- Lithium-ion batteries experience charge capacity loss during their lifecycle caused by mechanical phenomena. In this study, a discrete element method (DEM) simulation model, to link the local mechanical behaviour in the positive electrode active layer to its global mechanical properties, was developed. DEM is a suitable method to use as the electrode active layer has a granular structure and the model includes contact formulations for the active particles and the binder domain. Simulations of the calendering process and the measurement of the active layer's global mechanical properties is possible with the framework. The model developed can capture the pressure sensitivity of the active layer, which has been observed in experiments.
|
|
| 3. |
|
|
| 4. |
- Lundkvist, Axel, et al.
(author)
-
Discrete element modelling of the elastic-plastic and viscoelastic properties of a lithium-ion battery electrode layer
- 2024
-
In: Powder Technology. - : Elsevier. - 0032-5910 .- 1873-328X. ; 443
-
Journal article (peer-reviewed)abstract
- Mechanical degradation mechanisms are one of the leading causes of charge capacity loss in lithium-ion batteries. This study further develops a discrete element method (DEM) simulation framework, which investigates how the local contact behaviour affect the global mechanical properties of the active layer. The local microstructure consists of active particles held together by a binder domain, making up a granular medium. This study investigates the impact of the layer's global properties from the type of particle contact model. Experiments were also performed to measure size distribution and the material properties of the active material. The time dependency of the active layer, stemming from the viscoelastic binder domain, was studied in relaxation simulations, which were based on experimental measurements.
|
|
| 5. |
- Lundkvist, Axel
(author)
-
Discrete element modelling of the mechanical behaviour of lithium-ion battery electrode layers
- 2024
-
Licentiate thesis (other academic/artistic)abstract
- Since their introduction in the late 20th century, lithium-ion batteries have become the leading battery technology for portable devices and electric vehicles due to their high energy density and rechargeability. However, the increasing demand for a longer battery life span is hindered by the fading of the battery’s charge capacity over prolonged use. This reduction in charge capacity stems from electrochemical and mechanical degradation of the battery cells. The main research focus in the literature has been on the chemical degradation of battery cells. However, the mechanical degradation also substantially contributes to the battery’s capacity degradation. Therefore, it is crucial to understand the mechanical properties of the battery cells to be able to mitigate mechanical degradation. The battery’s mechanical degradation stems from the electrode layers’ constituents. This thesis aims to model the positive electrode’s mechanical properties by recreating its granular microstructure using the discrete element method.In Papers 1 and 2, a discrete element method modelling framework is developed, which can reconstruct a positive electrode layer of a lithium-ion battery, simulate manufacturing processing steps, and determine the mechanical properties of the electrode layer. The framework uses two contact models, representing the positive electrode material in the form of particles and a binder agent, which gives the electrode layer its structural integrity. The framework is used to link the mechanical behaviour of the electrode particles and the binder agent to the mechanical behaviour of the entire electrode layer. The framework is able to capture the layer’s pressure sensitivity and relaxation behaviour, properties which have been displayed in the literature through experimental testing.
|
|
| 6. |
- Lundkvist, Axel, et al.
(author)
-
Geometric and Material Modelling Aspects for Strength Prediction of Riveted Joints
- 2023
-
In: Metals. - : MDPI AG. - 2075-4701. ; 13:3, s. 500-
-
Journal article (peer-reviewed)abstract
- The aim of this study is to develop a methodology for static strength and failure mode simulation of hot-driven riveted joints. The purpose is to be able to accurately estimate a rivet joint's static strength behaviour and its failure mode without relying on experiments, to save both time and resources during the design of joints. The non-linear finite element analysis modelling framework considered the rivet joint configurations and geometry, the material properties of the plate and rivet as well as the clamping force of the hot-driven rivet. A ductile damage model was also implemented to capture the stress softening of the materials and the failure modes of the joints. Using experimental data from literature, the modelling framework is validated, and it is shown that it is able to capture the strength behaviour and failure modes of different configurations of rivet joints markedly well. The effect of the rivet pre-load on the mechanical response of the joint is also studied and it is shown that the strength of the joint increased with the increase in rivet pre-load. The modelling framework is then applied to an industrial component. The modelling framework is used to compare welding and riveting as joining methods in a component built in two grades of high-strength steel. It is found that the welded joint possessed greater strength compared to the proposed riveted joint. However, using the proposed simulation methodology developed, a riveted joint with matching strength to the welded joint could be designed.
|
|
