No description available.

This study aims to improve the design of the feeding system of industrial horizontal rubber injection moulding machines. There are many ways to implement this research. Still, the suitable design is to implement such a mechanism that will help reduce the operator intervention in the feeding system of the injection moulding machine. The FEM analysis is used to understand the real-world situation on the feed part or assembly. This analysis also provides the ability to detect the potential issues in the design, including the tension area of design and the weak spots. In the industrial horizontal rubber injection moulding machine, the same technique is used to evaluate the feeding system and based on it, the roller conveyor is designed. The 3D model is implemented using Cad software. The selection of motor for the roller conveyor and the power transmission system is also extracted to maintain the quality and enhance the feeding system's productivity. In the research, a design is presented to improve the feeding system in which the conveyor belt is designed, which provides complete support for the feeding system.

The hyoid apparatus in laryngeally echolocating bats is unique as it forms a mechanical connection between the larynx and auditory bullae which has been hypothesized to transfer the outgoing echolocation call to the middle ear during call emission. Previous finite element modeling (FEM) found that hyoid-borne sound can reach the bulla at an amplitude likely heard by echolocating bats; however, that study did not model how or if the signal could reach the inner ear (or cochlea). One route that sound could take is via stimulation of the eardrum – similarly to that of air-conducted sound. We used µCT data to build models of the hyoid apparatus and middle ear from six species of bats with variable morphology. Using FEM, we ran harmonic response analyses to measure the vibroacoustic response of the tympanic membrane to hyoid-borne sound generated during echolocation and found that hyoid-borne sound in all six species stimulated the eardrum within a range likely heard by bats. Although there was variation in the efficiency between models at higher frequencies, there are no obvious morphological patterns to account for it. This suggests that hyoid morphology in laryngeal echolocators is likely driven by other associated functions and warrants further inquiry. Note: This work was published open access in the Journal of Integrative Organismal Biology (https://doi.org/10.1093/iob/obad004)

Material flow in friction stir welding is largely uncharacterized due to the difficulty in material flow measurement and visualization in metals. This study investigates plasticine for use as an analog for modeling material flow in friction stir welding (FSW) of metals. Qualitative comparisons between welded plasticine and metal sections exhibit many similarities. The transient temperature response of the plasticine also shows the same qualitative behavior as welds conducted in metal. To quantify its similarity to metal, the plasticine is further analyzed through compression tests to characterize its strain, strain-rate, and temperature sensitivities. A detailed analysis is presented which defines the criteria for rigorous mechanical and thermal similarity between metals and analog materials. The mechanical response of the plasticine is quantitatively similar to many aluminum and steel alloys. In addition to the mechanical properties of the plasticine, thermal properties are measured and thermal similarity is investigated. Generally, complete thermal similarity cannot be achieved in FSW. However, given the similarities between other critical parameters, and observed qualitatively similarity, it is possible to satisfy similarity approximately, such that information can be obtained from the physical model and extrapolated to metals. Using plasticine, material flow behavior in FSW is investigated under various operating conditions. The physical model permits visualization and characterization of material flow around a suspended welding tool. Depending on operating conditions, several material flow regimes are observed, including simple extrusion with substantial tool/material slip, defect formation, a region of rotating material adjacent to the tool, and vertical deformation. Material flow and frictional heating in FSW are also investigated using a three-dimensional numerical model. Two mechanical boundary conditions are investigated, including 1) a sticking constant velocity, and 2) a slipping variable shear stress model. The constant velocity model generally over-predicts the extent of material flow in the weld region. The variable shear model predicts simple extrusion of material around the tool, and substantial tool/material slip. Additionally, the variable shear model exhibits a region of diminishing shear stress, velocity, and pressure at the back advancing side of the pin, suggesting formation of an internal void. The limited deformation, low velocities, and indication of void formation agree well with flow visualization studies using plasticine under identical operating parameters.

This master thesis studied the possibilities of implementing new handbook methodologies for sizing of corner and bathtub attachments with respect to static strength.  Parametric studies of corner and bathtub attachments were performed in order to examine the effect of boundary conditions and vital dimensions with respect to static strength. The parametric studies were performed by solving FE-models of attachments with different dimensions. Variables such as flange thickness, end-plate thickness, end-plate length and total attachment width were varied in order to identify geometric trends for prediction of cross-sectional loads.  The FE-models consisted of a bolt, washer and attachment assembly. The bolt was subjected to pre-tension and contact conditions were applied in between each part. The parametric study examined the cross-sectional loads of critical cross sections of the end-plate, bolt, flanges and back.  The parametric study of the bathtub attachment resulted in verification of critical failure modes from earlier handbook methodology, as well as a foundation for a new handbook methodology for sizing with respect to static strength. The parametric study of the corner attachment resulted in an identification of critical failure modes. The non-symmetric configuration of a corner attachment was found to result in larger load distribution in the bolt shank cross section.

No description available.

Vi har jämfört elevers resultat på matematiska problem på en traditionell skola och en montessoriskola. Vi har även jämfört flickornas resultat med pojkarnas.

The aim of this thesis was to investigate the effect of clearance and tolerance in bolted joints when there is a mismatch between the bolt holes. A parametric study with seven different cases was analyzed in this project; four double bolt configuration and three triple bolt configuration, with variation of the size of the bolt hole misalignment, the diameter of the bolt and the thickness of the plates. All analyses were performed with the aid of the FEM commercial software Abaqus, all the models were modelled with 3D brick elements. Despite bolted connections being subject of several investigations, no study about this matter for structural engineering purposes had been performed before. The results indicate that for connections with a low number of bolts a misalignment of the bolt clearance can cause a serious reduction in the ultimate bearing capacity of a joint and it indicates that the Eurocode 1993 1-8 might be overestimating the ultimate bearing capacity for some cases.

Infrastrukturen i Sverige åldras, uppskattningsvis finns det drygt 2000 broar i landet som är 70 år eller äldre. Det finns flera aspekter att titta på för att utvärdera äldre broars kondition och FE modellering är ett vanligt verktyg som används vid utvärdering. För stålbroar är det ofta utmattning som sätter gränsen för hur länge de kan hållas i drift under säkra förhållanden. Syftet med arbetet var att utvärdera nyttan av FE modeller med olika precision med hänsyn till noggrannheten i deras genererade resultat och kostnad. En stålbro har studerats i detalj, Gamla Lidingöbron och specifikt två punkter på dess bågspann. Ritningar av bron och mätdata från forskningsprojektet \textit{Smart tillståndsbedömning, övervakning och förvaltning av kritiska broar} har legat till grund för arbetet. Mätdata utgjordes av tidshistorier över spänningsvariationer i de två studerade punkterna vid flertalet tågpassager över bron. Punkterna finns på bågspannets sekundära bärverk. Fyra modeller har skapats i BRIGADE/Plus med olika precisionsgrad och spänningshistorier för de studerade punkterna har genererats. Spänningshistorierna har sedan utvärderas med Palmgren-Miners delskadeteori för utmattning. Den förväntade ekonomiska nyttan för varje modell har uppskattats beroende av analyskostnad, sannolikheten för utmattningsbrott samt kostnad för ett eventuellt brott. På grund av brons strukturella verkningssätt blev de förenklade modellernas utmattningsresultat mycket lika resultaten från modellen med hög precisionsgrad. De verkliga axellasterna var mindre än de dimensionerande som användes i modellerna. Detta ledde till att de uppkomna spänningarna i stålet från modellerna blev större än de verkliga, men visade ett liknande beteende. Resultatet blev att modellernas utmattningskapacitet enbart utgjorde ca en femtedel av kapaciteten enligt mätningarna. Resultatet från beräkningen av den förväntade nyttan visade att det inte är ekonomiskt motiverat att använda en modell med hög precision framför en eller flera förenklade modeller. Slutsatsen blev att hög precision i en teoretisk modell inte entydigt är bättre än en förenklad modell. Arbetet har utförts vid institutionen för bro och stålbyggnad på KTH i samarbete med Sweco Civil AB. / The infrastructure in Sweden is aging. More than 2 000 bridges in the country are 70 years or older. When assessing the condition of older bridges, several aspects should be taken into account. FE modeling is one common tool to use in a bridge assessment. Fatigue is generally what limits the service life of steel bridges. The aim of this work was to evaluate the utility of higher precision in FE models, regarding the accuracy of their generated results and costs. One steel bridge has been studied in detail, Old Lidingö Bridge and specifically two points on its arc span. Drawings of the bridge and measurement data from the research project \textit{Smart Condition Assessment, Surveillance and Management of Critical Bridges} has provided the basis of this work. Measurement data has been collected from the two selected points on the bridge with strain gauges, registering the time history of the variations in tension during train passages on the bridge. Four models with different levels of precision have been created in BRIGADE/Plus. These models have generated time histories of the varying tension during  train passages. The time histories have been evaluated with Palmgren-Miner's cumulative damage model for fatigue. The expected economic utility of each set of models has been estimated based on the cost of the analysis, the likelihood failure caused by fatigue and the cost of failure. Because of the structural behavior of the bridge, the results of the simplified models became very similar to the results of the high precision model. The actual axle loads were less than the design loads used in the models. Because of this, the calculated tensions in the models became larger than the actual tensions. This also resulted in the fatigue capacity of the models only being about one fifth of the capacity according to the measurements. The calculation of the expected utility showed that it is not economically justified to use a model with higher precision over models with less precision. High precision in a theoretical model is not unambiguously better than a simplified model. The work has been carried out at the Department of Structural engineering and bridges at KTH in cooperation with Sweco Civil AB.

In the past few decades, on-board electronic devices have been developingtremendously in automotive industry, and it is believed that the trendof electrication and autonomous driving will sustain in the near future.Thus, passenger cars are going to suer from more severe electromagneticenvironment, especially from an EMC's perspective.This thesis is an investigation and overview on a possible simulationmethod applied to vehicle radiated immunity test in accordance withISO 11451-2 standard. The preliminary work of geometry clean-up onthe model obtained from structural dynamics department and the overallmethod development have been discussed. The main contribution of thisthesis is to build up a feasible workow that is suitable for vehicle EMCsimulations based on FEM electromagnetic simulation software ANSYSHFSS. In addition, some potential future work within this area is alsosuggested by the author. / Under de senaste decenniernas gång har elektroniken inom bilindustrinsett en kraftig utveckling, och att trenden pekar på batteridrivna och självkörande bilar som en trolig verklighet inom en snar framtid. Den utvecklingen kan också leda till att personbilar kan drabbas i en alltmer elektro-magnetisk omgivning, speciellt från EMC’s perspektiv.Denna uppsats har som syfte att undersöka och skapa en överblick genom en simulering som utfärdar ett strålningsimmunitets-test på ett fordon i enlighet med standarden ISO 11451-2. Det preliminära arbetet med geometri rening på modellen som erhållits från avdelningen för strukturdynamik och den övergripande metodutvecklingen har diskuterats. Det som med denna uppsats avser att bidra med i huvud-del är att bygga upp ett möjlig arbetsflöde som lämpar sig för EMC-simuleringar för fordon med FEM elektro-magnetiska simulations-mjukvaran ANSYS HFSS. Vidareställs frågor för ytterligare arbete och forskning av uppsats-författaren.