Problemformulering: Bakgrunden till vår uppsats startade när vi själva började söka extrajobb vid sidan av studierna och upptäckte ganska snart att de flesta jobb av intresse som var vakanta på arbetsmarknaden gick att söka via bemanningsföretag. Därför blev vi intresserade av att få veta varför företag väljer att gå via bemanningsföretag istället för att anställa själva. Syfte: Syftet med denna studie är att få reda på hur företag ser på de kostnader som uppstår vid inhyrning av personal. Metod: I det här avsnittet kommer vi att presentera vårt val av metod. Vi kommer att berätta utförligt hur vi ska gå tillväga för att genomföra vår undersökning. Även förhållningssättet kommer att presenteras som utmynnar i senare delen av uppsatsen i analys och slutsats. Teori: I teoriavsnittet presenterar vi de teorier som vi valt att använda oss av, bland annat "Det Intellektuella kapitalet" och "Porters fem konkurrenskrafter". Även här presenteras de vetenskapliga artiklar som vi har funnit intressanta att studera inför arbetet. Empiri: I det här avsnittet presenteras våra intervjufrågor respektive svar. Analys: Här analyserar vi de svar vi har fått vid intervjuerna med hjälp av de teorier som vi presenterar i teorikapitlet. Slutsats: Slutsatsen är den väsentligt viktiga delen i vår uppsats. Här drar vi slutsatser med hjälp av de nya perspektiv vilka vi har fått vid intervjuerna. Källkritik: Här presenterar vi vår egen åsikt om de artiklar, böcker och svar som vi fått vid intervjuerna. Nyckelord: Intellektuellt kapital, Porters fem krafter, Bemanningsföretag, Bemanningsbranschen.

Bionischer Leichtbau realisiert mit Applikationen an gängige FEM-Programme nach dem Vorbild der Natur

Dry adhesion systems adhere via physical bonds without any significant contribution from a liquid medium. In nature, these systems are found among the footpads of spiders, lizards and many other small animals, with high adhesion force, low detachment force and elfcleaning properties. These features are highly interesting for biomimetic man-made adhesives. Heavy animals have an adhesion force much higher than its muscle force, and to enable detachment, they have evolved a functional surface with hair-like structures called setae. Each seta branches into numerous microcontact elements that interact with the contacting area. This thesis continue on previous work, analyzing the functional surface in terms of contact geometries and stress distribution, and considers, for the first time, the effect of thermal fluctuations. Numerical and analytical results show how the muscle force is concentrated to a small fraction of the adhesion area, where each microcontact element is trapped in a potential well. The rate of detachment depends on the maximal concentration of stress across the crocontacts. When a seta is axially loaded, the concentration of stress is minimized, whereas radial loading amplifies the concentration of stress by a factor of maximum 68 and enable detachment with the animal’s limited muscle force. The results give theoretical insight in the adhesion and detachment of a functional surface. This knowledge is valuable and can be considered when constructing man-made adhesives with inspiration from nature’s dry adhesion solutions.

A request of material change when performing repairs on composite parts of SAABs JAS 39 Gripen has lead to the initiation of this project. The aim is to create a quicker and more robust repair method. The requested method of repair is to use a direct-cured repair patch made of CFRP fabric instead of CFRP tape and to mount the patch with a scarf joint, see Figure 1.1. The fabric patch should then provide a robust quasi-isotropic repair, where the operator not is dependent of complete design data such as ply-directions etc. Today tape repairs are made on tape laminate and fabric repairs made on fabric laminate. The new method is to repair tape laminate with a fabric patch. This project will evaluate the possibility of implementing this method. The work started with a literature study to find out how repairs in composite parts of the airframe are being performed today. SAABs in-house analytical tools were then used to try to predict the results and examine some of the details in the questions at issue. Finite element models were then constructed to simulate a previous physical test program conducted to validate a repair method using a step joint and a direct-cured repair patch. If the FE models could show similar results as the physical tests the results from the FE models then can be assumed to be credible. The results of this project indicate that the change from fabric to tape in the repair patch can be done without disturbing the load path of a quasi isotropic composite laminate. Fabric repairs in orthotropic composite plates results in a knock-down of about 40%. The use of a scarf joint instead of a step joint should also work well as the repair patches show similar strains in the centre of the patches. The difference between step joint and scarf joint is the strain near the edge of the patch. It increases with scarf joint and it may lead to an earlier fibre failure in the repair patch. Results from the analysis of the bonded joint indicate that a scarf joint yields in a lower and more evenly distributed shear stress than the step joint. This indicates that the bonded joint in the step joint will reach failure earlier then the scarf joint.

No description available.

In order to be competitive in the markets of today, more and more companies try to make their production more effective by automation. Consequently more money is invested in robots and the operability of the robots becomes increasingly important. Undetected faults may result in damages, both to the robot itself and to the operator, which make detection and prediction of faults important. The gearboxes responsible for controlling the motions of the robots are essential for their functionality. In order to increase the understanding about them this project focuses on creating a model of the stress distribution inside a gearbox. First, the geometry of the gearbox is measured and digitalized using a vernier caliper, a protractor, a ruler and the CAD-program Solid Works. Then the geometry is imported into the finite element program Samcef. In Samcef, the interaction between the parts in the gearbox is modeled and a dynamic simulation of the stresses inside the gearbox during a robot cycle performed. Since there are almost no experience about Samcef at ABB SECRC, part of the project is to evaluate the program and comment the experiences received when using it. Two main power transmission steps are identified, modeled and simulated. They are merged together into a big model where both steps are present. This model consists of all the essential power transmission inside the gearbox, from input to output. The load applied is a rotational movement on the input axle during a robot cycle.

This report is the result of a thesis as been implemented during the spring term 2009 at the University of Gävle. The company Bruks produces mobile chippers which are used for chipping logging slash, roundwood and parts of trees. The chipper is powered by a separate diesel engine and the chipper can be assembled on trucks, trailers or some other carrier vehicles. When the chip has passed the chipper drum, the chip is collected in an integrated bin which is mounted on the vehicles frame with dumping yokes. When these dumping yokes were designed they were probably created with large material dimensions. The aim with the degree project is hence to study the strengths of materials and, if possible, to suggest an arrangement that can decrease the total weight on the dumping yoke on Bruks´ mobile chippers 805 CT. The CAD-program Pro/ENGINEER was used during the project for outlining the 2Ddrawings, as distributed of constructors on Bruks, to solid 3D-parts. The three-dimensional assembly from Pro/ENGINEER was transferred to Pro/MECHANICA. The construction is complex and contains many components, and therefore the model has been divided into two different parts, the external and the internal dumping yoke. The conclusion of the degree project is that the product generally is not over dimensioned. However there are many options for optimizing, mainly on the external dumping yokes.

This thesis describes the work process and the results for the development of a newkind of ergonomic cleaning mop, ranging from basic concept to a virtually productionready digital prototype. The project was made in cooperation with, Ömer Altun, whowas also the project supervisor, and whose plan it is to launch this new product onthe market in a foreseeable future. The mop is meant to be used by both professionalcleaning staff and ordinary home users. What makes this product unique is that it hasa movable center piece that simplifies the cleaning under low furniture.The work began with the establishment of a product requirements specification andlater a study of similar products and existing functional models was conducted. Afterthese surveys the work began with refining the existing concepts in order to makethem more complete. In consultation with Ömer, further refining of one of these newconcepts was conducted, but was split into seven smaller steps.After the initial refining process, effort shifted into the investigation and selection ofappropriate materials and manufacturing methods. At this stage, two experimentswere also conducted and subsequently used to support the final decisions concerningthe choice of materials and design.When the materials and methods were adopted, a detailed CAD model of the wholeproduct and related technical drawings was made and also a number of FEM-analyseson all critical details, to ensure that performance requirements were met, wasconducted. These CAD models are closer described in detail in the chapter“Detaljkonstruktion”.In the final sections of discussion and evaluation are suggestions for furtherimprovements. And also some evaluation of the work process and the problems andsolutions encountered during the project execution.

Tractors of today come equipped with a CAN-system. A CAN-system sends information from sensors to electronic control units who process the signals. The sensors measure several interesting parameters such as force, pressure and speed for various components of the tractor. This thesis discuss a force sensor which is placed in the pivot of the tractors three point linkage, the sensor measure the horizontal reaction force from the load that the tractor is exposed to. Signals from this sensor can be used to measure the force from any implement that the tractor is exposed to during an operation. The results from this thesis can be used for research purposes, for example, to compare implements from different manufacturer or to optimize the implement settings during an operation. However, there is a problem that this thesis aimed to solve by developing a method which can be put into practice. When a constant force from an implement is acting on the three point linkage, the reaction force in the pivot of the three point linkage (where the force sensor is attached) is going to vary depending on the angel of the lower lift arm. It is not uncommon that the angel of the lower lift arm is varying, because different implement and soil require different settings on the linkage. This means that the force which is measured by the sensor may vary in size even though the actual force does not vary. To solve this problem, theoretical calculations have been performed and equations to describe the variation of the reaction force depending on the geometry have been created. The theory has also been verified by a finite element analysis and a practical verification test. The conclusions from these three parts correspond to each other. Theoretically that means by knowing the horizontal reaction force (measured by the force sensor) and the angles of the geometry on the three point linkage (can be measured with a position sensor) you can calculate the force an implement influence the tractor with. However, there is a problem which prevents this method from being completely reliable. It is only working when the impact force is completely parallel to the horizontal plane. Since many implements are being pulled to the soil (plow, cultivator, etc.) in practice there are also vertical forces affecting the tractor. This is no problem to solve in theory, but in practice this method does not compensate for the vertical force. This vertical force should be examined more carefully before the method can be used reliably in full scale.

Our project consists of two parts (A and B). In part A we solve a linear elasticity problem with implementing a rotated  approximation method and simulating the problem in commercial softwares (COMSOL and SolidWorks). To evaluate the results we implement an analytical eigenvalue solver. As a simple case, we use a cube with side length of L = 1m made of Alloy steel with density of 7850 Kg/m^3.  In part B we implement a time dependent linear elasticity problem on a beam made of Alloy steel with density of 7850 Kg/m^3 with size of 1x0.1x0.01m. We use the implicit method to solve our problem. The frequency results in part A show that the rotated Q1 approximation method works more accurate than the commercial software.