This master thesis was conducted at Volvo Construction Equipment at the cabs department in Eskilstuna, Sweden. The work comprises 30 credits and was carried out by Dennis Björnberg from Mälardalen University during the fall 2015. Volvo Construction Equipment is one of the largest manufacturers of construction equipment and among their products are wheel loaders. The assignment involves an investigation and evaluation of today’s windshield and wiper system for large wheel loader which is in need of improvements as today’s solution has reliability issues. As a result the cab department wants new concepts and solution for next generation of wheel loader that considers the current solution issues. This project aims to develop new concepts which answer the research questions developed to guide the project. The executed development process consists of three phases; problem formulation, concept development and finally product development. The first phase, problem formulation involves literature studies, project definition and demand specifications to formulate and guide the project in the right direction. The second phase develops primary concepts and comparisons with competitors and other solutions in a benchmarking leading to a development of the final concept in phase three. The development process resulted in a wide concept solution consisting of a new shaped windshield, a wiper system adjusted to the new windshield and with new frameless wiper blades, a conceptual pneumatic air system to investigate if an air barrier can keep the windshield clean and a recommendation regarding hydrophobic coatings for windshield´s. The development process resulted in a concept proposing a new shaped windshield system where the side sections is curved for a smooth transition between the sections and a modified wiper system with a wider wiping angle and more square The conclusion drawn from the project it that it is possible to improve today’s solution to develop new conceptual solutions but almost all the performance originates from the windshield´s shape and curvature. The recommendations include among others to further investigate the windshield´s shape and it effects in the wiper system, develop prototypes to further investigates the efficiency of a pneumatic system in dry environments as a replacement for wiping without fluids and to watch the development of new hydrophobic materials and coatings with better durability and lifetime.

Dirt ingress in hydraulic cylinders is one of the sources that leads to pollution of hydraulic systems. There are already several test rigs to investigate external contamination mechanisms. However, until now only the behavior of the whole sealing system was analyzed. A new testing method to understand the dirt particle transport between a reciprocating motioned rod and a wiper is presented. The new approach aims to avoid known issues such as limited reproducibility and long duration. The paper describes the test rig design and operating principle. First measurement results are shown.

Ce mémoire présente une étude expérimentale et numérique sur le crissement du contact verre/élastomère lubrifié à l’eau, avec pour application le bruit des essuie-glaces. Le crissement provient d’une vibration auto-entretenue de l’échantillon d’élastomère sur l’un de ses modes. Des expériences menées à vitesse stabilisée montrent qu’il existe trois régimes de frottement. À basses vitesses, le frottement est constant et élevé malgré le lubrifiant : c’est le régime limite. À hautes vitesses, la formation d’un film hydrodynamique assure un frottement faible. La transition a lieu à des vitesses intermédiaires où le frottement décroît fortement avec la vitesse de glissement : c’est le régime mixte. On observe que la vibration auto-entretenue n’apparaît que durant le régime mixte. Un modèle masse-ressort-amortisseur à un degré de liberté permet de rendre compte de ces observations : le système est instable lorsque la pente du coefficient de frottement avec la vitesse est négative et supérieure à un seuil relié à l’amortissement interne de l’élastomère. L’instabilité est de type stick-slip et son apparition est bien prédite quantitativement par ce critère de stabilité. Le mécanisme générant l’instabilité est donc d’origine tribologique et sa compréhension requiert un examen approfondi du contact au cours de la transition. Les observations directes du contact par microscopie montrent que le contact élastomère/verre lubrifié est hétérogène et composé d’une multitude de spots. On divise le contact en trois familles : les spots de contact sec (sans aucun film d’eau entre l’élastomère et le verre), le contact intermédiaire caractérisé par un mince film d’eau entre l’élastomère et le verre, et une zone totalement lubrifiée. On propose une loi de frottement de type additive prenant en compte la contribution de ces trois familles. La composante de frottement sec est proportionnelle à l’aire des spots secs. Une composante d’origine capillaire, causée par la présence de ponts capillaires dans le contact, est proportionnelle au périmètre du contact intermédiaire. La composante hydrodynamique est toujours négligeable. / This thesis presents a study about the squeal noise induced by a lubricated elastomer/glass contact. The industrial application of this work, based on experimental and numerical approaches, is the wiper blade squeal noise. The hearing squeal noise is caused by a self-induced vibration of the elastomer sampled on one of its mode. Experiments produced for different sliding speeds reveal three regimes of friction. At low speeds, friction coefficient is constant and high : this is the boundary regime. For high speeds, the forming of an hydrodynamic film between the elastomer and the glass induces a low friction coefficient. The transition occurs for intermediate speeds for which the friction strongly decreases with the sliding speed : this is the mixed regime. One observes that the self-induced vibration is present only during the mixed regime. A model, based on a single degree-of-freedom mass-spring-damper oscillator submitted to a velocity-dependent frictional force, allows to understand these observations : the system is unstable when the variation of the friction coefficient according to the sliding velocity is negative and higher than a threshold depending on the elastomer intrinsic material damping. The instability is stick-slip kind, and its occurrence is well predicted using this stability criterion. Thus the origin of the instability is tribological and its full understanding needs the consideration of the contact evolution during the transition. Direct contact observations by microscope show that the lubricated elastomer/glass contact is heterogenous and composed of a multitude of spots. The contact is divided in three families : dry contact spots (without any lubricated water film between elastomer and glass), the intermediate contact defined by a thin film layer between elastomer and glass, and a totally lubricated zone. Using these three kinds of contact spots, an additive friction law is established. Friction component associated with dry contact depends on dry spots area. Intermediate contact generates capillary force, caused by the presence of capillary bridges in the contact. The associated force depends on the intermediate contact perimeter. The hydrodynamic component is always negligible.

The diploma thesis deals with construction design mechanically rake screens with hydraulic drive. The diploma thesis is composet of several parts, in a first past is an overwiew of mechanical method of cleaning screams. The second part deals of diploma thesis deals with product design rakes raking mechanism. The third part is an analysis of machine parts and describe their functions. It is then carried out stress analysis using fine element methods (FEM) in the program I-deas.

Dirt ingress in hydraulic cylinders is one of the sources that leads to pollution of hydraulic systems. There are already several test rigs to investigate external contamination mechanisms. However, until now only the behavior of the whole sealing system was analyzed. A new testing method to understand the dirt particle transport between a reciprocating motioned rod and a wiper is presented. The new approach aims to avoid known issues such as limited reproducibility and long duration. The paper describes the test rig design and operating principle. First measurement results are shown.

Automotive parts may be the cause of very annoying friction-induced noise and the source of many customer complaints. Indeed, when a wiper operates on a windshield, vibratory phenomena may appear due to flutter instabilities and may generate squeal noise. As squeal noise generated by wiper system is a random and complex phenomenon, there are only few studies dealing with the wiper noise. The complexity of this phenomenon is due to the cinematic of the movement and to the various environmental parameters which have an influence on the appearance of the noise. This master thesis is a research and development project and presents a numerical simulation methodology used in the aim to reduce and eradicate squeal noise of wiper systems.  In the first part, the finite element model representing a wiper system and the numerical simulation methodology will be presented in detail. In the second part, stability analysis will be carried out in nominal studies and in designs of experiments. Parametric studies will also be achieved to understand the behavior and the influence of each considered input parameters. Two wiper blades, with the same geometry but with different material, will be considered for the different studies. These two wiper blades will be examined to figure out when squeal noises appear.

La conduite à grande vitesse d’une voiture dans des conditions dangereuses, tel un environnement très poussiéreux, est une des situations auxquelles sont confrontés les conducteurs. Dans ce cas, les essuie-glaces doivent fonctionner correctement et nettoyer efficacement le pare-brise sale pour à la fois assurer la sécurité des passagers et le bon fonctionnement des différents organes du véhicule. La mise en route des essuie-glaces entraîne l’activation des buses d’injection du liquide nettoyant qui s’atomise et qui se dépose sur les essuie-glaces et le pare-brise. Une fine couche du liquide se développe sur les surfaces des balais d’essuie-glace. Lorsque l’injection s’arrête et que les essuie-glaces continuent leur mouvement, la fine couche de liquide interagit avec le champ d’écoulement d’air extérieur. Il en résulte une génération de gouttelettes qui sont emportées par l’air en s’éloignant des balais d’essuie-glace. Une partie de ces gouttelettes impacte le pare-brise avec pour conséquence un nettoyage insuffisant et une mauvaise visibilité pour le conducteur. Dans cet exemple, les essuie-glaces peuvent à la fois enlever la poussière du pare-brise mais aussi être à l’origine de la formation des gouttelettes et de leur impact sur le pare-brise. Le phénomène d’interaction air-liquide sur les essuie-glaces produisant une génération de gouttelettes, leur transport et leur impact sur le pare-brise est connu sous le vocable ‘Overspray’ dans le domaine de l’automobile. Il est important de tenir compte du phénomène d’Overspray pour la conception et laréalisation des essuie-glaces. Bien que ce phénomène ait été mis en évidence depuis longtemps, les mécanismes qui le régissent demeurent encore peu connus. C’est pour cette raison que les essuie-glaces ne parviennent pas à satisfaire tous les critères de qualité liée à leur fonction. Cette thèse vise à une meilleure compréhension du phénomène de l’Overspray en mettant l’accent sur les interactions air-liquide pour la génération des gouttelettes, et plus particulièrement sur les conditions critiques où le film commence à s’atomiser. Cette étude a été réalisée essentiellement par voie expérimentale à partir de laquelle un modèle a été proposé. / Driving the car in hazard conditions, like an environment with a lot of dust, is a case which is encountered often by the drivers. The wiper blades have to work successfully and clean the dirty windshield for both the safety of the passengers and the functionality of the car. Activating the car nozzle jets, washer is ejected from the nozzles towards the wiper blades and the windshield. A thin layer of liquid is developed on the surfaces of the wiper blades. When the nozzle jets stop and the wiper blades continue to move, the thin layer of liquid interacts with the strong external air flow field. The result of the interaction is the generation of droplets which are transported by the air flow far from the wiper blades. However, a part of those droplets impact on the windshield resulting in an insufficient cleaning of the screen and the deterioration of the driver’s sight. The wiper blades may remove the dust from the screen but they will cause the droplet impact on it. The phenomenon of the air-liquid interaction on the wiper blades involving the droplet generation, transport and impact on the screen is known as Overspray in the automotive domain. The Overspray is an important parameter for the design and development of the wiper blades. Although Overspray has been observed quite early, little is known for the mechanisms involved in. Thus, the wiper blades still suffer to clean the windshield adequately in such conditions. The current thesis aims to give a deep insight in the Overspray focusing more on the air-liquid interactions for the droplet generation, especially, the investigation of the critical conditions for the onset of the film atomization from the blade surfaces. For that reason mainly experimental and theoretical work has been conducted.

Denna rapport beskriver ett examensarbete inom integrerad produktutveckling vid Högskolan i Skövde. Arbetet utfördes i samarbete med företaget The Best of Sweden AB där uppdraget var att utveckla ett fäste och skyltar för bakrutetorkare på personbilar. Utvecklingsprocessen för produkten började med en förstudie där bland annat kundbehov undersöktes. Under förstudien undersöktes även olika faktorer som kan komma att påverka produkten i dess användningsmiljö, exempelvis bilars aerodynamik och kraften i bakrutetorkarens motor. En fältstudie genomfördes på existerande torkararmar som fästets och skyltarnas mått grundas på. Resultatet från förstudien var en kravspecifikation som det slutliga konceptet ska kunna ställas mot. Olika strukturerade designmetoder användes under konceptgenerering samt konceptutvärdering som följdes upp av detaljutveckling. Förslag på material och tillverkningsmetod samt ett kostnadsförslag togs fram. Resultatet blev en fästanordning och skyltar för bakrutetorkaren på personbilar vilket gör det möjligt för användaren att montera personifierade skyltar i olika format. Fästanordningen består av ett fäste och en rem, där remmen spänns åt runt torkararmen och håller fästet på plats. Produktens symmetri medför att den kan placeras på torkararmar oavsett om torkararmen går vänster- eller högervarv. / This thesis discloses a bachelor degree project in Product Design Engineering at the University of Skövde. The project was performed in collaboration with a company called The Best of Sweden AB where the assignment was to develop a universal mount and signs for rear window wipers on cars. The development process started with a prestudy where customer needs where analyzed. Different factors which affect the product in the environment of use, such as the aerodynamics of cars and the force in the rear window wiper engine, were examined as well during the prestudy. A field study was carried out on existing rear window wipers which became the basis of the dimensions of the signs as well as the mount. The result of the pilot study ended in a list of requirements that the final concept was to be compared to. Different structured design methods was used during concept generation as well as concept evaluation which was followed by a development of the details of the final concept. A proposition of material selection and manufacturing method was determined as well as an estimation of manufacturing cost. The result was a fastening device and signs for rear window wipers on cars which makes it possible for the user to mount personalized signs if various different formats. The fastening device consists of a base mount and a strap, where the strap is tightened around the rear window wiper and keeps the base mount in place. The symmetry of the product enables it to be mounted to a rear window wiper that either rotates clockwise or counter-clockwise.

This study investigated methods to reduce herbicide application through improved targeting of weeds, thereby also reducing damage to pastures. The focus was to evaluate and improve wiper and spot-spraying application techniques for pasture herbicides as they reduce chemical use by treating just the weed. Wiper application of herbicides was shown to be a useful technique for controlling Californian thistles. In one trial, a stem reduction of over 90% when assessed 10 months post application was achieved with a double pass of clopyralid, metsulfuron and glyphosate when the plants were treated at the post-flowering stage and were vigorously growing. A double pass was superior to a single pass for glyphosate and triclopyr/picloram, but not for clopyralid and metsulfuron. Subsequent trials produced poor results possibly because of the stressed condition of the thistles and their growth stage as well as lack of consistency in wiper output and operator differences. Despite wiper applicators usually being selective, some damage to pastures was observed in the field, and from a series of experiments it was concluded that rain falling soon after wiper application was the likely cause of pasture damage. An innovative and highly sensitive technique using a spectrophotometer was developed to measure herbicide output from wiper applicators. A spectrophotometer could accurately measure clopyralid concentrations as low as 0.02 g active ingredient in a litre of water. The Eliminator and Rotowiper outputs were found to be highly variable while the Weedswiper was more consistent although it applied less herbicide than the other two wipers. Spot spraying experiments confirmed that glyphosate and metsulfuron create bare patches by damaging both grass and clover while clopyralid and triclopyr/picloram only eliminate clover. However, metsulfuron patches stayed bare for much longer while glyphosate ones quickly filled up with weeds and clover. Ingress of clover stolons appeared to be more important than re-establishment from seed in the recovery of patches. The bigger the damaged patch, the higher the likelihood of recolonisation by opportunistic weeds. Bioassay studies found that over-application of clopyralid and triclopyr/picloram provided residual activity up to 18 and 30 weeks, respectively, thereby potentially preventing re-establishment of white clover. The negative effects on clover seedlings from metsulfuron ranged from 3 to 6 weeks for standard and high rates, respectively, with a stimulatory effect on seedlings thereafter for up to 18 weeks. Dose-response curves for the application of metsulfuron and triclopyr/picloram into the centre 5% versus full plant coverage of Scotch thistle and ragwort rosettes showed that application of herbicide to the centre 5% was as effective at the same concentration and greatly reduced the risk of damage to pasture.

Diplomová práca, ktorá vznikla v spolupráci so spoločnosťou AUFEER DESIGN (AFD), sa zaoberá analýzou konkrétneho stieračového mechanizmu automobilu. Najprv je uvedená stručná história stieračov. Stieracie sústavy sú potom rozdelené podľa ich usporiadania a spôsobu pohonu. V nasledujúcej kapitole je formulovaná problémová situácia, problém a systém podstatných veličín. Kinematické veličiny kľúčových bodov mechanizmu sú určené analytickým aj numerickým prístupom. Výpočtový model pre kinematickú analýzu je vyvinutý v Matlabe a SimMechanics. Ďalšia časť je venovaná vytváraniu konečno-prvkového modelu v programe ANSA. Všetky deformačne-napäťové analýzy sú vykonané v programe Abaqus. Prvá z nich je parametrická štúdia, ktorá odhaľuje kritické polohy mechanizmu z hľadiska tlakového namáhania určitých súčastí. Mechanizmus v kritických polohách je potom zaťažovaný so zablokovanými ramenami stieračov. Nakoniec sú urobené lineárne analýzy straty vzpernej stability súčastí, u ktorých môže nastať, nasledované nelineárnymi analýzami so zahrnutými imperfekciami.