The dissertation thesis deals with the determination of uncertainty of strain measurement and the stress using resistance strain gages. You can find two methods to define the uncertainty in the thesis, GUF and MMC, and both are applied for measurements carried out with resistance strain gages. Definition of the measurement uncertainty was set for the strain measured by uniaxial and biaxial strain gages. The uncertainty of the stress was defined for linear strain gages, T Rosettes and Rosettes. There were universal mathematic-technical models defined to measure strain and stress, these models can be used either for standard and special measurements i.e. high-temperature, or for measurements in radiation field. Each part of the strain uncertainty and stress is analyzed from the point of view of a size of uncertainty and a form of probability of the function that strain and stress can adopt. The maximum focus was dedicated to the mistakes influencing measured strain like strain gage properties, installation and operating influences, external influences, time effects and the influence of the measured object. There are two mistakes influencing the stress described and analyzed in the thesis, the mistake of the Young’s modulus of elasticity and the mistake of the Poisson’s ratio. The thesis is conceived as a complex of information related to the measurement uncertainties using the resistance strain gages and methods of defining the measurement uncertainty in a way that the experimenter can apply the gained info and methods in the required measurements. The final chapters give representative examples to define measurement uncertainties for uniaxial and biaxial stress applying GUF and MMC method. The thesis also includes the experiment that compares measured values of strain, stress and measurement uncertainties, using several different types of strain gages at different temperatures, with theoretical calculation of strain and with stress. The experiment was carried out using the displacement sensor that works on an elementary principle of bending load.

The aim of this thesis is the construction of a diagram of fracture strain for high strength steel OCHN3MFA and its application for the estimation of fracture toughness of this material. The first part of the thesis contains the necessary theoretical framework for numerical modelling of tensile tests of various specimens - smooth specimen, specimen with a notch and specimen with a circumferential crack, it describes the influence of triaxiality on the fracture of bodies and the possibilities of construction of the diagram of fracture strain. Subsequently, a numerical model of these specimens is created using the finite element method (FEM). A non-linear, elastoplastic calculation is performed. Fracture is identified by means of comparing the true stress versus the strain obtained from tests with the finite element analysis results. Stress–strain states of specimens at the moment of fracture are obtained from a numerical model. A diagram of fracture strain is constructed, and it is used to estimate the fracture toughness of a cracked body. Finally, a local approach, which uses the diagram of fracture strain, and a classical approach of fracture mechanics, especially the stress intensity factor, are compared.

A torque transducer or a torque sensor is a device for measuring and recording the torque on a rotating system. Torque transducers usually employ strain gauges to measure the torsional moment applied to a rotating shaft.It is to be noted that for an ideal torque transducer, it should measure only the strain that is caused by a torque. Strain due to bending load should be compensated as per the Wheatstone bridge arrangement. However, because of geometrical tolerances and assembly errors, the compensation doesn’t occur and the measured strain is a resultant of bending loads and axial loads which are undesired to measure the torque associated with the system. An analytical formulation has been developed using Matlab and this thesis gives the generalized indication of the strain due to all the associated loads. The user shall also entire the region where the strain needs to be computed and this knowledge can be useful for placing the strain gauges in the shaft accordingly. Initially, the formulation is based on a standard Torque Transducer used at Atlas Copco and then, a generalized result has been developed. The theoretical formulation is verified using the ProEngineer Mechanica software. The end user shall enter the different loads (if any) along with the geometrical tolerance values and the output will be an indication of the strain at point, strain at a region and sensitivity. The main intention of the thesis is to create a better understanding of the strain associated with the twisting, bending and axial loads and also the geometrical imperfections. The user can also make a decision on the location of strain gauges on a shaft for maximum accuracy. Finally, the differences in error from different possible configurations are compared and a conclusion has been made based on factorial design pertaining to design of experiments. / Momentgivare är små sensorer som används för att mäta och registrera vridmomentet på en roterande axel. Momentgivare baseras vanligtvis på trådtöjningsmätare för att mäta vridmomentetet kring axeln de är fixerade på. Det skall noteras att en ideal momentgivare endast bör mäta den yttöjning som uppkommer på grund av ett vridmoment. Den belastning som uppkommer på grund av axelns böjning kompenseras bort med hjälp av en Wheatstonebrygga. Men på grund av geometriska toleranser och monteringsfel kan kompensationen bli felaktig och då påverkas det uppmätta momentet även av böj och axialbelastningar vilket är oönskat. En analytisk modell har utvecklats med hjälp av Matlab och denna rapport undersöker de olika lastfallens bidrag till momentfelet. Användaren kan ange området där yttöjningen skall beräknas och utifrån de beräkningarna bestämma var trådtöjningsgivarna bör placeras. Inledningsvis är beräkningarna baserade på en av Atlas Copcos momentgivare och sedan har generaliserade resultat utvecklats. De teoretiska beräkningarna verifieras med hjälp av programmet ProEngineer Mechanica. Användaren kan ange vilka belastningar som axeln känner samt de geometriska toleransvärdena och modellen beräknar då ytspänningen för den valda regionen. Det huvudsakliga syftet med denna avhandling är att skapa en bättre förståelse av ytspänningen som uppkommer på grund av vridning, böjning och axiella belastningar och även geometriska imperfektioner. Modellen kan också användas för att göra beräkningar som visar var töjningsgivare bör placeras på axeln för maximal precision. Slutligen har de introducerade felet från de olika möjliga konfigurationerna jämförts och en slutsats har dragits baserat på faktorförsök.

The brain is a complex organ and its response to the mechanical loads at all strain rates has been nonlinear and inelastic in nature. Split-Hopkinson Pressure Bar (SHPB) high strain rate compressive tests conducted on porcine brain samples showed a strain rate dependent inelastic mechanical behavior. Finite Element (FE) modeling of the SHPB setup in ABAQUS/Explicit, using a specific constitutive model (MSU TP Ver. 1.1) for the brain, showed non-uniform stress state during tissue deformation. Song et al.’s assertion of using annular samples for negating inertial effects was also tested. FE simulation results showed that the use of cylindrical or annular did not mitigate the initial hardening. Further uniaxial stress state was not maintained is either case. Experimental studies on hydration effects of the porcine brain on its mechanical response revealed two different phenomenological trends. The wet brain (~80% water wt. /wt.) showed strain rate dependency along with two unique mechanical behavior patterns at quasi-static and high strain rates. The dry brain’s (~0% water wt. /wt.) response was akin to the response of metals. The dry brain’s response also observed to be strain rate insensitivity in its elastic modulus and yield stress variations. Uncertainty analysis of the wet brain high strain rate data revealed large uncertainty bands for the sample-to-sample random variations. This large uncertainty in the brain material should be taken into in the FE modeling and design stages. FE simulations of blast loads to the human head showed that Pressure played a dominant role in causing blast-related Traumatic Brain Injury (bTBI). Further, the analysis of shock waves exposed the deleterious effect of the 3-Dimensional geometry of the skull in pinning the location of bTBI. The effects of peak negative Pressure at injury sites have been attributed to bTBI pathologies such as Diffuse Axonal Injury (DAI), subdural hemorrhage and cerebral contusion.

Friction stir welding (FSW) of HSLA steel commonly produces a hard zone (HZ) on the advancing side (AS) of the weld. Despite its detrimental effects on weld toughness, the mechanisms of its formation have not been thoroughly investigated and are not well understood. This paper investigates the various mechanisms in FSW believed to affect the weld HZ, namely: strain, strain-rate, peak temperature and cooling rate. Gleeble tests indicate that strain and strain rate have negligible effects on weld HZ with cooling rate and peak temperature as dominant effects. Jominy tests resulted in cooling rate having 270% greater influence than peak temperature on the formation of lath ferrite microstructures similar to what is observed in the HZ of FSW X65. Comparing weld HZ microstructures to Jominy tests, it is estimated that cooling rates on the AS of the weld are at least 150°C/s higher than the retreating side. Reducing the cooling rate on the AS will likely lead to an improved microstructure at the weld HZ.

High hydrodynamic pressure (HDP) treatment is a novel non-thermal technology that improves tenderness in foods by subjecting foods to underwater shock waves. In this study non-destructive and destructive testing methods, along with two mathematical models were explored to predict biomechanical behavior of beef loins subjected to HDP-treament. The first study involved utilizing ultrasound and imaging techniques to predict textural changes in beef loins subjected to HDP-treatment using Warner-Braztler shear force (WBS) scores and texture profile analysis (TPA) features for correlation. Ultrasound velocity correlated very poorly with the WBS scores and TPA features, whereas the imaging features correlated better with higher r-values. The effect of HDP-treatment variables on WBS and TPA features indicated that amount of charge had no significant effects when compared to location of sample and container size during treatment. Two mathematical models were used to simulate deformational behavior in beef loins. The first study used a rheological based modeling of protein gel as a preliminary study. Results from the first modeling study indicated no viscous interactions in the model and complete deformation failure at pressures exceeding 50 kPa, which was contrary to the real-life process conditions which use pressures in the order of MPa. The second modeling study used a finite element method approach to model elastic behavior. Shock wave was modeled as a non-linear and linear propagating wave. The non-linear model indicated no deformation response, whereas the linear model indicated realistic deformation response assuming transverse isotropy of the model beef loin. The last study correlated small- and large-strain measurements using stress relaxation and elastic coefficients of the stiffness matrix as small-strain measures and results of the study indicated very high correlation between elastic coefficients c11, c22, and c44 with TPA cohesiveness (r > 0.9), and springiness (r > 0.85). Overall results of this study indicated a need for further research in estimating mechanical properties of beef loins in order to understand the dynamics of HDP-treatment process better. / Ph. D.

Networks of crosslinked keratin filaments are abundant in epithelial cells and tissues, providing resilience against mechanical forces and ensuring cellular integrity. Although studies of in vitro models of reconstituted keratin networks have revealed important mechanical aspects, the mechanical properties of crosslinked keratin structures remain poorly understood. Here, we exploited the power of electron beam irradiation (EBI) to crosslink in vitro networks of soft epithelial keratins 8 and 18 (k8–k18) filaments with different irradiation doses (30 kGy, 50 kGy, 80 kGy, 100 kGy, and 150 kGy). We combined bulk shear rheology with confocal microscopy to investigate the impact of crosslinking on the mechanical and structural properties of the resultant keratin gels. We found that irradiated keratin gels display higher linear elastic modulus than the unirradiated, entangled networks at all doses tested. However, at the high doses (80 kGy, 100 kGy, and 150 kGy), we observed a remarkable drop in the elastic modulus compared to 50 kGy. Intriguingly, the irradiation drastically changed the behavior for large, nonlinear deformations. While untreated keratin networks displayed a strong strain stiffening, increasing irradiation doses shifted the system to a strain softening behavior. In agreement with the rheological behavior in the linear regime, the confocal microscopy images revealed fully isotropic networks with high percolation in 30 kGy and 50 kGy-treated keratin samples, while irradiation with 100 kGy induced the formation of thick bundles and clusters. Our results demonstrate the impact of permanent crosslinking on k8–k18 mechanics and provide new insights into the potential contribution of intracellular covalent crosslinking to the loss of mechanical resilience in some human keratin diseases. These insights will also provide inspiration for the synthesis of new keratin-based biomaterials.

Syftet med vårt examensarbete är att få mer kunskap kring varför kriminalitet har blivit ett alternativ för unga pojkar i vårt samhälle. Vi har valt att använda oss av självbiografier och teorierna strain och anomi för att förstå vilka sociala riskfaktorer som kan leda till ett kriminellt beteende. Genom att få en förståelse för riskfaktorer som inkluderar familj, vänner och miljö kan vi också nå en ökad förståelse varför kriminalitet blir ett alternativ. Det vi funnit är att det inte är enskilda riskfaktorer som bidrar till att unga pojkar väljer kriminalitet som ett alternativ. Det är först när flera riskfaktorer i kombination med varandra som unga människor når en ökad risk att bli involverade i ungdomskriminalitet och kriminellt beteende. De riskfaktorer som självbiografierna hade gemensamt var att samtliga växte upp i socioekonomiskt utsatta bostadsområden, med ensamstående mammor, låg inkomst och svaga skolresultat. Vad gäller riskfaktorerna så fann vi även att många av dessa pojkar hade vänt sig till droganvändning eller försäljning av droger som ett led in i kriminalitet. Vissa unga människor som utsätts för samma riskfaktorer kan likt huvudkaraktärerna i självbiografierna vända sig till kriminalitet. Det gäller dock inte alla eftersom de flesta människor som utsätts för liknande riskfaktorer inte vänder sig till kriminalitet som ett alternativ. Trots att vi inte fokuserade på individuella faktorer såsom karaktärsdrag fick vi en förståelse för att impulsivitet, risktagande och låg självkänsla kunde agera som riskfaktorer för att yngre pojkar rättfärdigar kriminella beteenden. Vår slutsats är att man behöver arbeta med riskfaktorerna för att ha en chans att förebygga att unga pojkar blir involverade i kriminella aktivitet och kriminellt beteende. / The aim of this study is to gain more knowledge about why crime has become an option for young boys in our society. We have chosen to use autobiographies and the theories of strain and anomi to understand which social risk factors can lead to a criminal behavior. By understanding these risk factors that include family, friends, and environment, we also gain an increased understanding of why crime becomes an alternative. What we found is that it is not individual risk factors that contribute to young boys choosing crime as an alternative. It is only when several risk factors are combined with each other that there is an increased risk for young people to be involved in juvenile delinquency or criminal behavior. The risk factors that the autobiographies had in common was that they grew up in a socio-economically vulnerable residential area, with single mothers, low income and with poor school results. As for the risk factors, we also found that many of these boys had turned to drug use or selling drugs as a way into crime. Some young people who are exposed to the same risk factors can, like the main characters in the autobiographies, turn to crime. However, this is not the case for everyone as most people exposed to similar risk factors do not turn to crime as an alternative. Although we did not focus on individual factors such as character traits, we gained an understanding that impulsivity, risk-taking and low self-esteem could act as risk factors for younger boys justifying criminal behavior. Our conclusion is that you need to work with the risk factors to have a chance of preventing young boys from becoming involved in criminal activity and criminal behavior.

This study aims to investigate the individual's experience of conscious consumption reduction in relation to society's consumption norms. By not focusing on motives or causes behind the change, but instead illustrating the subjective and social consequences, the study provides a deeper understanding of how the individual's self-perception and social relationships are affected. This will be studied based on the following questions “How does a conscious reduction in consumption affect the individual's self-perception and identity in relation to society's consumption norms?” and “What social and cultural effects do individuals experience when they reduce their consumption on purpose, and how does this affect relationships within the individual's immediate circle?” Previous research has been interested in understanding why individuals change their consumption behaviour. Social resistance from society and the surrounding community has also been a broad area of research. A significant focus has also been to study consumption patterns from a sustainability perspective, where research identifies challenges and how today's society can be treated. This study aims to contribute with an in-depth understanding of how conscious consumption reduction affects the individual's life aspects and relationships, which may have far-reaching implications for our understanding of society's changing consumption patterns. The theoretical framework of the study consists of Emilé Durkheim's social coercion consisting of the normative coercion, the cultural coercion, the material coercion and the structural coercion. In combination with this, Robert K. Merton's social tensions, taken from his strain theory, are also applied. The study is based on qualitative semi-structured interviews, where we study 8 individuals' perceived effects of consumption reductions. The results suggest that a reduction in consumption strengthens the individual's empowerment and promotes self-reflection. Through reduced emphasis on external factors, individuals shape their self-perception beyond materialism. Even though their consumption reduction violates norms, they are met with curiosity. These individuals appear to act as agents of normative change by raising awareness of the impact of consumption and promoting a transformation towards a more sustainable way of living. / Denna studie ämnar undersöka individens upplevelse av medveten konsumtionsminskning i förhållande till samhällets konsumtionsnormer. Genom att inte rikta in sig på motiv eller orsaker bakom förändringen, utan i stället åskådliggöra de subjektiva och sociala konsekvenserna, ger studien en djupare förståelse för hur individens självuppfattning och sociala relationer påverkas. Detta kommer studeras utifrån frågeställningarna ”Hur påverkar en medveten minskning av konsumtion individens självuppfattning och identitet i förhållande till samhällets konsumtionsnormer?” och “Vilka sociala och kulturella effekter upplever individer som minskar sin konsumtion med avsikt, och hur påverkar detta relationer inom individens närmaste krets?” Tidigare forskning har intresserat sig för att förstå varför individer ändrar sitt konsumtionsbeteende. Även det sociala motståndet från samhälle och omgivning har varit ett vida forskningsområde. Ett betydande fokus har även varit att studera konsumtionsmönster ur ett hållbarhetsperspektiv, där forskningen identifierar utmaningar och hur dagens samhälle. Denna studie avser bidra med en ingående förståelse för hur medveten konsumtionsminskning påverkar individens livsaspekter och relationer, vilket kan ha långtgående implikationer för vår förståelse av samhällets föränderliga konsumtionsmönster. Studiens teoretiska ramverk består av Emilé Durkheims sociala tvång bestående av det normativa tvånget, det kulturella tvånget, det materiella tvånget och det strukturella tvånget. I kombination med detta tillämpas även Robert K Mertons samhälleliga spänningar, taget från hans strainteori. Studien baseras på kvalitativa semistrukturerade intervjuer, där vi studerar 8 individers upplevda effekter av konsumtionsminskningar. Resultatet tyder på att en minskning av konsumtion stärker individens egenmakt och främjar självreflektion. Genom minskad betoning på yttre faktorer, formar individer sin självuppfattning bortom materialism. Trots att deras konsumtionsminskning bryter mot normer, möts de av nyfikenhet. Dessa individer tycks agera som agenter för normativ förändring genom att öka medvetenheten om konsumtionens påverkan och främjar en omvandling mot ett mer hållbart levnadssätt.

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