In this work, understanding the microstructural effects of monotonic and cyclic failure of wrought 7075-T651 and cast A356 aluminum alloys were examined. In particular, the structure-property relations were quantified for the plasticity/damage model and two fatigue crack models. Several types of experiments were employed to adapt an internal state variable plasticity and damage model to the wrought alloy. The damage model was originally developed for cast alloys and thus, the model was modified to account for void nucleation, growth, and coalescence for a wrought alloy. In addition, fatigue experiments were employed to determine structure-property relations for the cast alloy. Based on microstructural analysis of the fracture surfaces, modifications to the microstructurally-based MultiStage fatigue model were implemented. Additionally, experimental fatigue crack results were used to calibrate FASTRAN, a fatigue life prediction code, to small fatigue-crack-growth behavior. Lastly, a set of experiments were employed to explore the damage history effect associated with cast and wrought alloys and to provide motivation for monotonic and fatigue modeling efforts.

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Bakgrund Att drabbas av cancer, oavsett i vilken form, är påfrestande för individen på olika plan. Livet påverkas både fysiskt, psykiskt och socialt. Biverkningarna av sjukdomen och dess behandling kan variera mellan individer. En av de vanligaste biverkningarna är extrem trötthetskänsla, fatigue, och i och med detta kan många gånger den fysiska aktiviteten minska. Tidigare studier har visat att det finns flera positiva effekter av fysisk aktivitet både under och efter cancerbehandling. I denna litteraturöversikt sammanställs studier som har belyst hur patienter med cancerdiagnos har upplevt att deras fatigue har påverkats av fysisk aktivitet. Syfte Syftet med studien är att belysa upplevelser av fysisk aktivitet vid fatigue hos patienter med cancerdiagnos. Metod Denna icke-systematiska litteraturstudie grundar sig på 15 vetenskapliga artiklar, publicerade 2017–2022, som bestod av både kvantitativ och kvalitativ design. Sökningar genomfördes i databaserna PubMed och CINAHL samt genom manuell sökning. Integrerad analys användes för att sammanställa resultatet. Resultat Dataanalysen ledde fram till två huvudkategorier: Underlättar behandlingen och Ökad livskvalitet. Underlättar behandlingen indelades i underkategorierna Mindre biverkningar, Minskning av upplevda symtom och Ökad kunskap. Ökad livskvalitet indelades i underkategorierna Bättre sömn och mindre förekomst av depression, Ökad fysisk styrka och Mindre upplevd trötthet. Slutsats I denna studie framkommer att fysisk aktivitet har en positiv inverkan på fatigue hos patienter med cancer. Slutsatsen blir att vårdpersonal bör rekommendera fysisk aktivitet på en personcentrerad och individanpassad nivå till patienter under och efter cancerbehandling. Mer forskning behövs dock för att frambringa evidens om den fysiska aktivitets inverkan på cancerrelaterad fatigue. Detta kan leda till framtagande av riktlinjer för vårdpersonal om hur de kan öka patienternas kunskap, intresse och medvetenhet om de positiva effekterna fysisk aktivitet har vid cancer. / Background To be affected by cancer, regardless of its form, is very stressful for the individual in different ways. Life is impacted in a major way both physical and psychologically as well as socially. Side effects of the disease and its treatment vary largely between subjects. One of the most common side effects is fatigue, and due to this the individual´s physical activity can become diminished. Previous studies have shown that there are many positive effects of physical activity both during and after cancer treatment. In this literature review we compile studies that have illuminated how patients with a cancer diagnosis have experienced how their fatigue has been affected by physical activity. Aim The aim is to enlighten the experiences of physical activity in patients with fatigue related to cancer diagnoses. Method This non-systematic literature study bases its results on 15 scientific articles, published 2017–2022, amongst these are both quantitative as well as qualitative studies. Article searches were made in the PubMed and CINAHL databases as well as manual searches. Integrated data-analyses were used to analyse the articles. The chosen articles went through a quality assessment with the help of Sophiahemmet university’s assessment tool. Results The data analysis led to two main categories: Facilitates treatment and Increased quality of life. Facilitates treatment was divided into the subcategories Less side effects, Reduction of perceived symptoms and Increased knowledge. Increased quality of life was divided into the subcategories: Better sleep and reduced incidence of depression, Increased muscle strength and Decreased perceived fatigue. Conclusions In this study it became evident that physical activity has a positive effect on fatigue in patients with cancer. The conclusion shows that the healthcare staff should encourage and recommend physical activity in a personified as well as individually appropriated level to patients during and after their cancer treatment. However, more research is needed to produce evidence of the impact of physical activity on cancer-related fatigue. This can lead to the development of guidelines for healthcare professionals on how they can increase patients' knowledge, interest and awareness of physical activity and the positive effects for patients with cancer.

The couple stress theory as presented by Mindlin, Koiter, Stokes and others is reviewed with particular attention being given to stress concentration and size effects. That theory is compared on a qualitative and quantitative basis with Neuber's theory for stress concentration for very small or sharp notches and with observed notch sensitivity effects in aluminum and steel. It is established that, in order to explain observed elastic size effects in these materials, the new material constant ℓ which is characteristic of the couple stress theory must be on the order of magnitude of .02". In order to determine order of magnitude of the constant, a series of experiments was designed based on a thin plate analysis developed here. The plate theory uses the basic assumptions of classical plate theory as well as several, as explained in the text, necessary when couple stress is included. The formulation resulted in a set of equations for plate deflection including classical and couple stress terms in such a way that when the constant ℓ was allowed to be zero, the classical equations resulted. Experimentally, it was found that the couple stress effect in steel and aluminum is at least one order of magnitude too small to account for observed size effects as was suggested by Mindlin. In addition, the magnitude of ℓ was found to be such that its effect would undoubtedly be clouded by inhomogeneity and anisotropy of metals at the microstructural level. The results represent the only known experimental data at the time of publication dealing with couple stress in metals and would seem to be the next obvious step in the development of the theory which has proceeded on a purely mathematical plane. An alternate approach to account for the effects of microstructure in notch sensitivity is discussed. / Ph. D.

Past efforts at implementing Load Spectrum Generation and Neuber Control have centered around minicomputers and analog circuits. The use of a personal computer to implement the tasks is presented. On implementation of the load Spectrum Generation software, the response of the Materials Testing System was investigated for distortion and attenuation. In particular, the effect of the resolution of the waveform on the test system response was noted. There was negligible attenuation for full scale frequencies of up to 20 Hz. Greater waveform resolution was required at lower frequencies than at higher frequencies. On implementation of the Neuber Control program, the accuracy obtained at the Neuber hyperbolas was noted. Better accuracy was obtained at ramp frequencies below 0.1 Hz. Based on the results obtained after implementing the Load Spectrum Generator program and the Neuber Control program, the performance of the personal computer in controlling fatigue tests is evaluated. Cost effectiveness and versatility favor the use of a personal computer for the control of fatigue tests. / Master of Science

Active damage control is a new technique which mimics the self-repairing capability of biological beings and can be used to greatly increase the structural integrity and fatigue life. This thesis describes two approaches used in active damage control: direct stress cancellation and indirect stress cancellation. Direct stress cancellation is illustrated using an example of active crack damage control with embedded shape memory alloy actuators. Both experimental and theoretical investigations have been conducted to analyze the damage control mechanism. The approach of indirect stress cancellation is demonstrated with active fatigue damage control of adhesive joints. The damage and active control mechanisms of the adhesive joints have been experimentally and theoretically investigated. / Master of Science

The response of a flake mat to the mechanical stress applied during consolidation is a function of mat structure, raw material properties and the environmental conditions created during pressing. This research project was aimed at improving the understanding of raw material behavior during the hot-pressing of wood based composites by examining the response of a wood flake mat to the compression encountered during press closure in the flakeboard manufacturing process. The structure of a flakeboard mat can be considered to be that of a cellular material, the properties of which are governed by the cellular geometry, or arrangement of cells, and the properties of the solid cell wall material. A method for quantifying the cellular structure of a wood flake mat was developed and implemented. The structure of thin mat sections and small flake mats was quantified using image analysis techniques. The applicability of theories developed for modelling the compressive behavior of cellular materials to the consolidation of wood flake mats was investigated using thin mat sections. Narrow mat sections and small laboratory mats has similar void sizes but significantly different void shapes. Void size was not significantly affected by flake orientation, but void shape was. / Master of Science