The focus of this diploma thesis is the design of a travel trailer. The work consists of two parts—analytical, which deals with the formal description of the travel trailer, its historical development, technical part, and the design analysis. The second part, drawing on the research, then provides the actual design solution along with its styling solution, technical solution, the ergonomic solution, colour as well as graphic solution.

This thesis deals with stress analysis of tandem platform trailer TVL10. The first part is devoted to description of trailers and their parts. The second part presents and evaluates the results of measuring acceleration and vibration of the trailer, and it describes the concrete chassis of a tandem trailer. There is included an analysis of the existing structure, design modifications and stress calculation and evaluation of newly designed chassis structure. The thesis is developed in cooperation with PANAV, a.s.

The purpose of this thesis is to calculate strenght of materials used in bale trailer and it's construction modifications. This work presents the design of new frame construction. After that the frame is checked via the finite elements method.

The aim of this study is to investigate the use of multi-body vehicle simulation models to predict the suspension forces acting on the chassis of the vehicle, in order to perform durability analyses. Traditionally, durability of vehicles is evaluated with proving ground tests. This implies that a physical prototype of the vehicle is required before its durability can be evaluated. If we were able to evaluate the durability of the vehicle without any physical part or a full prototype of the vehicle available, great cost and time savings may be gained. These possible gains have lead to the use of computer aided engineering (CAE) tools. These tools have supplemented the proving ground durability test by using historical measured data and/or predicted data from vehicle simulation models, as input to the durability analyses i.e. Finite Element Analyses (FEA). The usefulness of the historical test data is limited and many of the vehicle simulation models that are used to predict the input data, have not been validated. In this study a validated mathematical model of a 40 ton flat bed tri-axle semi-trailer, able to predict the suspension forces, is created. The validation of the full vehicle model includes correlations for displacements, velocities, accelerations and forces of various vehicle parameters. A validated mathematical model of the air springs, that includes mass transfer and flow effects for use in full vehicle dynamic simulations, is also developed. The results obtained indicate that the air spring model, integrated into the full vehicle model, is able to give relative accurate predictions of displacements, velocities, accelerations and forces of various vehicle parameters, over a discrete road event and over a rough road. / Dissertation (MEng)--University of Pretoria, 2009. / Mechanical and Aeronautical Engineering / Unrestricted

This thesis investigates the design of a local planning method for a reversing single joint tractor-trailer system that can be used in a sampling-based motion planner. The motion planner used is a Rapidly-exploring Random Tree (RRT) developed by Scania. The main objective of a local planning method is to generate a feasible path between two poses, which is needed when expanding the search tree in an RRT. The local planning method described in this thesis uses a set of curves, similar to Reeds-Shepp curves, feasible for a single joint tractor-trailer system. The curves are found by solving a constrained optimization problem that adheres to the kinematic model of the system. The reference for the tractor is generated by discretizing the path between curves. The reference for the trailer is generated by simulating the mission backwards where the curve radiuses are used as input. Simulating the mission backwards circumvents the instability of the system when reversing. The generated references are then compared to references generated by a lattice-based motion planner. The length of the references generated by the RRT are smaller than those generated by the lattice-based motion planner in simple open environments. The RRT had issues finding a path in cases where the environment was complex while the lattice-based motion planner found a path in every scenario. The computational time was significantly lower for the RRT in all simulations. The RRT generates all references between any two given poses while the lattice-based motion planner approximate the start and goal poses to the closest vertex in the search-space.  The references generated by the RRT did not perform optimally when small turns were needed along the curves due to the distance needed for maneuvering the tractor. Therefore, a new optimization problem has to be defined for which the small turns are considered.

Effectively communicating climate change issues to the public have been proven to be a complicated task. Increasing scientific research explaining how humans have caused changes on climate, have led to a decreasing concern, contributing to the Psychological Climate Paradox. The aim of this study is to analyze how the issue of climate change is communicated in the documentary trailers of Anthropocene: The human epoch (Baichwal, Burtynsky & de Pencier, 2018) and Kiss the Ground (Tickell & Tickell, 2020), and whether these contribute to the Psychological Climate Paradox or not. To do so, the presence of three out of five barriers to effective climate communications, which help uphold the Psychological Climate Paradox were taken into consideration. The method of the research consisted of a modified Multimodal Critical Discourse Analysis (MCDA), focusing on the semiotic aspects of denotation and connotation, visual codes, and the linguistic aspect of vocabular choice The study concludes that the three psychological barriers which contribute to climate communication were clearly present in the Anthropocene trailer. However, the Kiss the Ground trailer rather presented the audience with the solutions to the barriers, known as the new Psychological Strategies, which Stoknes (2015) argues contribute to more effective climate change communication.

Commodity hauling of bulk goods is a growing enterprise that has expanded from hauling agricultural products to hauling many other bulk products. Commodity trailers are used to haul agricultural products from storage facilities to processing plants. These trailers are designed for highway use but are frequently required to work in field conditions as well. In many cases this environment overstresses these trailers and results in permanent irreparable damage. In addition to the structural problems of these trailers, the current systems for unloading the bulk produce from these trailers have serious inadequacies. While functional, the currently used chain and non-chain driven belt discharge devices are expensive and often problematic, requiring frequent maintenance and replacement. Furthermore, the discharge device also causes damage to the produce. This thesis provides innovative solutions to these two key problems and introduces a completely new trailer design that can be used for both field and road conditions. The main chassis of the trailer has a framework of ribs supported by two I-beams. This unique rib design combined with the main I beams act as large vertebra, which results in a rigid underbody that maintains flexibility and strength. Special consideration was taken while creating this design to account for dynamic loading on soft muddy soils or uneven surfaces while still maintaining the desired lightweight trailer characteristics. In addition to the improved trailer frame and body design, a simple and effective device for unloading bulk products was constructed. The new design-a belt-over-chain system-is actually two separate systems performing one job in unison with different characteristics and speeds. The system works by means of a hydraulic orbit motor that actuates the drive chains into motion. The weight of bulk commodities on the chain presses the unattached conveyor belt against the chain and cross-members, creating friction, which advances the conveyor belt. This thesis solves two of the problems associated with hauling bulk produce from the field to the storage facility and sets the groundwork for improving the hauling capabilities used to move commodities from the field. Finally, this thesis introduces a new commodity self-unloading trailer for hauling produce, which has a belt system that preserves quality and a body design that provides trailer longevity.

Both commuting to work and long-distance travelling with one's own bicycle have been intrend for years and a large market has emerged. While the reasons on the customer side aremainly sustainability and sporting activity, the companies offer customised products for manydifferent use-cases.In this master's thesis, a transport box for bicycles is being developed that can be taken on aplane, for example, and converted into a cargo trailer at the destination. A market researchshows that such a product is already available for certain folding bikes, whereas the goal is auniversal solution for utility bikes as well as mountain bikes.The methodological development follows a standard that divides the process into four phases.After the market research, main functions of the product are identified, which are "Transport abicycle as luggage" and "Carry goods during the bicycle ride". These are then divided intosub-functions in order to find different design variants for each function, combine them intodifferent drafts with the help of a morphological box and finally evaluate according totechnical and economic criteria, so that a final draft is determined at the end of this phase. It isa hard case providing enough space for different types of bicycles, that can be converted intoa trailer by mounting two wheels on the sides and a tow bar.In phase 3, the wheel size is set at 12 inches due to small space requirements and weight, andthe material is set to ABS-plastic for reasons of sustainability and mechanical properties.The final phase involves 3D design using Fusion360 with drawing derivation and validationof the model. The model shows that the requirements regarding geometry and weight havebeen implemented and that a practical transport option for bicycles has been found. In order topotentially launch the product on the market, further investigations such as FEM analysis ordynamic simulations are necessary. / Både pendling till arbetet och långväga resor med egen cykel har varit trendigt i flera år ochen stor marknad har vuxit fram. Medan anledningarna på kundsidan främst är hållbarhet ochsportaktivitet, erbjuder företagen kundanpassade produkter för många olika användningsfall.I detta examensarbete utvecklas en transportlåda för cyklar som till exempel kan tas med påett flygplan och omvandlas till en lasttrailer på destinationen. En marknadsundersökning visaratt en sådan produkt redan finns tillgänglig för vissa hopfällbara cyklar, medan målet är enuniversell lösning för både vanliga cyklar och mountainbikes.Metodutvecklingen följer en standard som delar in processen i fyra steg. Eftermarknadsundersökningen identifieras produktens huvudfunktioner, vilka är "Transportera encykel som bagage" och "Bära varor under cykelturen". Dessa delas sedan in i underfunktionerför att hitta olika designvarianter för varje funktion, kombinera dem till olika utkast med hjälpav en morfologisk box och slutligen bedöma enligt tekniska och ekonomiska kriterier, så attett slutligt utkast bestäms i slutet av denna steg. Det är en hård väska som ger tillräckligt medutrymme för olika typer av cyklar, och som kan omvandlas till en cycelkärra genom att manmonterar två hjul på sidorna och en dragkrok.I steg 3 sätts hjulstorleken till 12 tum på grund av små utrymmesbehov och vikt, ochmaterialet sätts till ABS-plast av hållbarhetsskäl och på grund av mekaniska egenskaper.Den sista steget innebär 3D-konstruktionen i Fusion360 med ritningsframtagning ochvalidering av modellen. Modellen visar att kraven på geometri och vikt har uppfyllts och attman har hittat ett praktiskt transportalternativ för cyklar. För att potentiellt kunna introduceraprodukten på marknaden krävs ytterligare undersökningar som FEM-analys eller dynamiskasimuleringar.

The less-than-truckload (LTL) transportation industry is highly competitive with low profit margins. Carriers in this industry strive to reduce costs and improve customer service to remain profitable. LTL carriers rely on a network of hubs and service centers to transfer freight. A hub is typically a cross docking terminal in which shipments from inbound trailers are unloaded and reassigned and consolidated onto outbound trailers going to the correct destinations. Freight handling in a hub is labor intensive, and workers must quickly transfer freight during a short time period to support customer service levels. Reducing shipment transfer time in hubs offers the opportunity to reduce labor costs, improve customer service, and increase competitive advantages for carriers. This research focuses on improving the efficiency of hub operations in order to decrease the handling costs and increase service levels for LTL carriers. Specifically, the following two decision problems are investigated: (1) assigning trailers to dock doors to minimize the total time required to transfer shipments from inbound trailers to destination trailers and (2) sequencing unloading and loading of freight to minimize the time required by dock employees. The trailer-to-door assignment problem is modeled as a Quadratic Assignment Problem (QAP). Both semi-permanent and dynamic layouts for the trailer-to-door assignment problem are evaluated. Improvement based heuristics, including pair-wise exchange, simulated annealing, and genetic algorithms, are explored to solve the trailer-to-door assignment problem. The freight sequencing problem is modeled as a Rural Postman Problem (RPP). A Balance and Connect Algorithm (BCA) and an Assign First and Route Second Algorithm (AFRSA) are investigated and compared to Balanced Trailer-at-a-Time (BTAAT), Balanced Trailer-at-a-Time with Offloading (BTAATWO), and Nearest Neighbor (NN). The heuristics are evaluated using data from two LTL carriers. For these data sets, both the total travel distance and the transfer time of hub operations are reduced using a dynamic layout with efficient freight sequencing approaches, such as the Balance and Connect Algorithm (BCA), the Balanced Trailer-at-a-Time with Offloading (BTAATWO), and the Nearest Neighbor (NN). Specifically, with a dynamic layout, the BCA reduces travel distance by 10% to 27% over BTAAT and reduces the transfer time by 17% to 68% over BTAAT. A simulation study is also conducted for hub operations in a dynamic and stochastic environment. The solutions from the door assignment and freight sequencing approaches are evaluated in a simulation model to determine their effectiveness in this environment. The simulation results further demonstrate that the performance measures of hub operations are improved using a dynamic layout and efficient freight sequencing approaches. The main contributions of this research are the integer programming models developed for the freight sequencing problem (FSP), based on the Rural Postman Problem (RPP). This is the first known application of the RPP for the FSP. Efficient heuristics are developed for the FSP for a single worker and for multiple workers. These heuristics are analyzed and compared to previous research using industry data. / Ph. D.

Some of the results of an extensive track testing program at the Center for Vehicle Systems and Safety (CVeSS) at Virginia Tech for evaluating the roll stability of commercial trucks with 33-ft A-double trailers are evaluated. The study includes straight-rail trailers with heavy and light loading conditions. Commercial trucks are more susceptible to rollovers than passenger cars because of their higher center of gravity relative to their track width. Multi-trailer articulated heavy vehicles, such as A-doubles, are particularly prone to rollovers because of their articulation and rearward amplification. Electronic stability control (ESC) has been mandated by the National Highway Safety Administration (NHSTA) for Class 8 trucks and busses since 2017. When detecting oversteer or understeer, ESC automatically activates the brakes at the correct side of the steer and/or drive axle(s) to regain steering stability. ESC, however, often cannot sense the likelihood of trailer rollover in multi-trailer articulated heavy vehicles because of the articulation between the trailers and tractors. As a result of this, trailers are often equipped with roll stability control (RSC) systems to mitigate speed-induced rollovers. Sensing the trailer lateral acceleration, RSC activates the trailer brakes to reduce speed and lower the likelihood of rollover. However, a limited number of past studies have shown that the trailer roll angle may provide an earlier indication of a pending rollover than the lateral acceleration. This study intends to provide further analysis in this regard in an effort to improve the effectiveness of RSC systems for trailers. An extensive amount of data from track testing with a 33-ft A-double under heavy and light loading is evaluated. Particular attention is given to lateral accelerations and trailer roll angles prior to rollover and relative to RSC activation time. The study's results indicate that the trailer roll angle provides a slightly earlier indication of rollover than lateral acceleration during dynamic driving conditions, potentially resulting in a timelier activation of RSC. Of course, detecting the roll angle is often more challenging than lateral acceleration, which can be detected with an accelerometer. Additionally, the roll angle measurement may be subjected to errors and possibly unwanted RSC engagement. The study's results further indicate that the trailer-based RSC systems effectively mitigate rollovers in both quasi-steady-state and dynamic driving conditions. / Master of Science / Some of the results of an extensive track testing program at the Center for Vehicle Systems and Safety (CVeSS) at Virginia Tech for evaluating the roll stability of commercial trucks with 33-ft A-double trailers are evaluated. "33-ft A-doubles" commonly refer to a commercial truck that has a tractor with two trailers (in this case 33-ft in length) that are connected by an A-dolly. Their modularity and ease of connecting and disconnecting at various drop stations have made such commercial vehicles a common scene on U.S. highways due to the proliferation of e-commerce cargo. Compared to a single-unit or tractor semi-trailer combination, the double- or triple-trailer configurations offer several logistical benefits that make them more advantageous. The multi-trailer vehicles can carry more cargo per driver, lowering driver, fuel, and equipment costs significantly. There are, however, some challenges to operating multi-trailer articulated vehicles. On average, their accidents are more expensive than single-trailer or single-unit trucks. Additionally, they are more susceptible to rolling over and causing property damage, injuries, and at times fatalities. To reduce rollovers, systems with automated braking, called roll stability control (RSC), are often installed on the trailers. RSC applies the trailer brakes if it senses that the vehicle speed — the primary cause of most commercial vehicle accidents — exceeds the safe limit for negotiating a turn. In this study, we intend to evaluate the effectiveness of roll stability control (RSC) systems for reducing the likelihood of speed-induced rollovers. We will also explore ways of improving their performance. Namely, we will evaluate whether sensing the lateral acceleration of the trailer or its roll angle would provide a better means for timely activation of RSC. The study's results indicate that, although more challenging to measure, the trailer roll angle provides a slightly sooner indication of a pending rollover than lateral acceleration. The results also suggest that RSC systems vastly reduce the number of speed-induced rollovers in trucks with 33-ft A-double trailers under different trailer configurations and cargo weights.