<p> A set of scales was created, the "Modified Conibear Scales" which can be used as a basis of comparison to rate the performance of other traps in the areas of impact energy, closing time and clamping force. Further, a detailed set of secondary non quantitative characteristics was presented.</p> <p> Using the above information, several promising traps were rated in order to assess these scales, give some immediate results and indicate promising traps or trap features. Further work in the field was facilitated by providing a detailed experimental procedure, complete lists of data and a calibrated trap for animal research.</p> / Thesis / Master of Engineering (MEngr)

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The heated flow within the silencers of heavy transport vehicles can easily reach temperatures of hundreds of degrees Celsius. The thermal loads can cause problems for certain components on a silencer. In this case it has been seen in previous testing that screw joints attaching suspension brackets onto the silencer tend to lose pretension when heat is applied. The goal with this project is to investigate possible causes of the pretension losses and gain a deeper understanding of the joint’sbehavior. The project starts with a pre study with the purpose of obtaining knowledge of what is usually taken into consideration when designing joints for heated applications thatcould cause pretension losses. This was followed by an experimental part. Two main tests are made, firstly a friction test to ensure that the friction properties ofthe studs used in previous clamping force measurements were up to specification. Comparisons to a second batch of studs is also conducted. The second test is an oven test were test specimens of the joint is heat cycled in different temperatures for different assembly torques. This, in order to gain a deeper understanding of the joints´plastic behavior. The test pieces are cycled a total of five cycles and clamping force measurements are made after the first and fifth cycle. Measurements of clamping force are conducted through both ultrasonic and micrometer measurements of screw elongation. The results of the oven test are compared to the results of a finite element simulation. The finite element model is a model of the same test piece as in the tests, it captures the clamping force losses due to plastic deformation of components at heat up. However, the finite element model has its´ limitations, especially in the way the threads are modelled. This is to be taken into consideration and possibly utilized when interpreting the results. The takeaways from the pre study are that creep and stress relaxation, as well asembedding is highly unlikely primary causes for the pretension losses. More instant effects like plasticity due to the applied load is deemed more likely. The friction tests concluded that both of the batches´ friction properties are up to specification, but onethe batches thread friction is on the lower side.The results from oven test shows a temperature dependency in the losses and clea rsigns pointing towards a plastic collapse. All of the clamping force seems to be lost at initial heat up, no further signs of losses after 5 cycles. In comparison with the finite element model the plastic tendencies shows yet again, but most of the losses is not captured in the simulation. By taking into account the known weaknesses of the model, the two threaded components, weld nut and flange nut, are considered to be possible subjects of plastic deformation causing the pretension losses. The two measurement techniques show big deviations between them. It is therefore hard to interpret the absolute results of the pretension losses. In order to that a furtherstudy of how to value the two techniques should be conducted.

Threaded fasteners tend to break and loosen when exposed to cyclic loads or potent temperature variations. Additionally, if the joint is held tightly to the structure, distortion will occur under thermal expansion issues. These complications can be prevented by identifying and regulating the clamping force to an appropriate degree – adapted to the properties of the joint. Torque-controlled tightening is a way of monitoring the clamping force, but it assumes constant friction and therefore has low accuracy, with an error of around 17% - 43%.This thesis investigates if the friction and clamping force can be estimated using the Extended and Unscented Kalman filters to increase the precision of the torque-controlled methodology. Before the investigation, data were collected for two widely used tightening strategies. The first tightening strategy is called Continuous Drive, where the angular velocity is kept at a constant speed while torque is increased. The second strategy is TurboTight, where the angular velocity starts at a very high speed and decreases with increased torque. The collected data were noisy and had to be filtered. A hybrid between a Butterworth lowpass filter and a Sliding Window was developed and exploited for noise cancellation.The investigations revealed that it was possible to use both the Extended and Unscented Kalman filers to estimate friction and clamping force in threaded fasteners. In Continuous Drive tightening, both the EKF and UKF performed well - with an averagequality factor of 81.87% and 88.38%, and with an average error (at max torque) of 3.54% and 4.09%, respectively. However, the TurboTight strategy was much more complex and had a higher order of statistical moments to account for. Thus, the UKF outperformed the EKF with an average quality factor of 93.02% relative to 24.49%, and with an average error (at max torque) of 3.50% compared to 4.19%

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It is common to use different construction materials in combination such as concrete, steel, wood and glass in order to optimize buildings. The purpose of this is to reduce weight and increase load capacity, but it also facilitates assembly and reduces construction time. Steel column bases anchored in concrete foundations are an example of a combination of interaction nodes between steel and concrete elements. This report studies the friction between the lower edge of the base plate and the grout, which is a function of the normal force of the column. The friction that occurs between the square washer and the foot plate has also been examined as a result of the tightening moment. The work has placed great focus on discussing the advantages and disadvantages of the different methods for transverse force absorption in column bases. Delimitations have been made, the attachment of the column to the base plate has not been taken into account in this report, as this depends on which column cross section is selected and must be checked for the specific case. To arrive at the results, an in-depth literature study was conducted to gather information on the various issues and a calculation model in Excel was created. The calculation model was used to check how large the design load-bearing capacity is for transverse force absorption in a column base, but the checks were only made for non-prestressed joints. This is because prestressed joints also have other factors that affect the transverse resistance, outside the purpose and issue of the work. The Excel model is based on producing the results from calculation with nominal clamping force and comparing it with clamping force calculated with tightening torque. The results will be reported in the form of graphs and tables, where it will be possible to read the difference in the dimensioning load-bearing capacity for transverse force absorption in non-prestressed joints at nominal clamping force and clamping force calculated with tightening torque. The report shows a clear difference in results, where the nominal clamping force became significantly larger and this is supported by handbook on screw joints, as it is mentioned that “it is not possible to give an exact value of the coefficient of friction due to the large number of factors that affect ”, this means that the impact on the clamping force will be large. / Det är vanligt förekommande att man använder sig av olika konstruktionsmaterial i kombination med varandra såsom betong, stål, trä och glas för att på så sätt kunna optimera byggnader. Syftet med detta är att minska vikt och öka belastningskapacitet, men det underlättar även montaget och minskar byggtiden. Pelarfötter av stål förankrade i betongfundament är ett exempel på en kombination av samverkansknutpunkter mellan stål och betongelement. I denna rapport studeras friktionen mellan underkant fotplatta och undergjutning, som är en funktion av pelarens normalkraft. Även friktionen som uppstår mellan fyrkantsbrickan och fotplattan kommer att undersökas som ett resultat av åtdragningsmomentet. Arbetet har lagt stor fokus på att diskutera för- och nackdelar med de olika metoderna för tvärkraftsupptagning i pelarfötter. Avgränsningar har gjorts, pelarens infästning till fotplåten har inte beaktats i denna rapport, eftersom detta är beroende av vilket pelartvärsnitt som är valt och måste kontrolleras för det specifika fallet. För att komma fram till resultaten utfördes en fördjupad litteraturstudie för att samla ihop information om de olika frågeställningarna och en beräkningsmodell i Excel skapades. Beräkningsmodellen användes för att kontrollera hur stor den dimensionerande bärförmågan är för tvärkraftsupptagning i en pelarfot, men kontrollerna görs endast för icke förspända förband. Detta eftersom förspända förband även har andra faktorer som påverkar tvärkraftskapaciteten, utanför arbetets syfte och frågeställning. Excel-modellen går ut på att ta fram resultaten ur beräkning med nominell spännkraft och jämföra den med spännkraft beräknad med åtdragningsmoment. Resultaten redovisas i form av grafer och tabeller, där man kan läsa av skillnaden i den dimensionerande bärförmågan för tvärkraftupptagning i icke förspända förband vid nominell spännkraft och spännkraft beräknad med åtdragningsmoment. Rapporten visar en tydlig skillnad i resultat, där den nominella spännkraften blev betydligt större och detta stöds av handbok om skruvförband, då det nämns att “det är inte möjligt att ge ett exakt värde på friktionskoefficienten på grund av det stora antalet faktorer som påverkar”, detta medför att inverkan på klämkraften blir stor.