Dissertations / Theses on the topic 'Bolted joints – Design'

A new approach is developed for the analysis and design of mechanically fastened composite lap joints under mechanical and thermal loading. Based on the combined complex potential and variational formulation, the solution method satisfies the equilibrium equations exactly while the boundary conditions are satisfied by minimizing the total potential. This approach is capable of modeling finite laminate planform dimensions, uniform and variable laminate thickness, laminate lay-up, interaction among bolts, bolt torque, bolt flexibility, bolt size, bolt-hole clearance and interference, insert dimensions and insert material properties. Comparing to the finite element analysis, the robustness of the method does not decrease when modeling the interaction of many bolts; also, the method is more suitable for parametric study and design optimization. The Genetic Algorithm (GA), a powerful optimization technique for multiple extrema functions in multiple dimensions search spaces, is applied in conjunction with the complex potential and variational formulation to achieve optimum designs of bolted composite lap joints. The objective of the optimization is to acquire such a design that ensures the highest strength of the joint. The fitness function for the GA optimization is based on the average stress failure criterion predicting net-section, shear-out, and bearing failure modes in bolted lap joints. The criterion accounts for the stress distribution in the thickness direction at the bolt location by applying an approach utilizing a beam on an elastic foundation formulation.

Bolted connections where used from the beginning of vehicle construction for joining two or more parts. The reliability of bolted connections is still a major problem. The objective of this research thesis is focused on an advanced monitoring system for bolted connections in vehicle construction. A mechanical “vibrating test bench”, which was developed by the aeronautical engineer Mr. Junkers, is being adapted, to suite the requirements of the automotive industry. It is designed according to DIN 65151 standards. The bolted connection is tightened to a specific torque to achieve the required preload forces and then exposed to an oscillating elastic shear force. The preload force and their loss are measured in relation to the number of load cycles. The ideal locking mechanism would be, if no settling occurs. Realistic in practice is the remaining of a sufficient preload force which doesn’t decry with time. The aim of this thesis is, to gain knowledge that will assist in the future control of the bolt locking procedure. The test bench can be used to verify the clamping capability of a bolted connection. With the dynamic computer-aided test system it will also be possible to test critical bolted joints and their safety, which reduces the probability of costly product recalls, or even severe cases of failure.

Includes bibliographical references (p. 185-189) Aims to determine the effect of partial interaction on the behaviour of the concrete beam, plate and bolt connector components of the composite plated beam. Develops design rules for the determination of the ultimate capacity for bolted plate reinforced composite beams.

Atualmente, a utilização do aço inoxidável em elementos estruturais ainda é por muitos engenheiros e arquitetos, considerada uma solução extravagante para os problemas da engenharia. Todavia, mudanças de atitudes dentro da construção civil e uma transição global para um desenvolvimento sustentável e redução em impactos ambientais tem seguramente provocado um aumento no uso do aço inoxidável. A maioria das normas de projeto de aço inoxidável atuais ainda são baseadas em analogias assumidas com o comportamento de estruturas de aço carbono. Todavia, o aço inoxidável apresenta quatro curvas tensão versus deformação não-lineares sem patamar de escoamento e região de encruamento claramente definidos (tração e compressão, paralela e perpendicular a direção de laminação), modificando assim, seu o comportamento global. Na presente investigação foram utilizados o aço inoxidável austenítico 304, e o aço carbono USI 300, ambos com tensão de escoamento similares, mas com tensões últimas e ductilidades distintos. Em elementos estruturais submetidos a tensões normais de tração, usualmente a ruptura da seção líquida representa um dos estados limites últimos a serem verificados. Com o objetivo de se avaliar a resistência a tração de elementos estruturais aparafusados em aço inoxidável, este trabalho executou um programa experimental inovador envolvendo ligações aparafusadas defasadas sob tração. O programa experimental foi executado em peças de aço carbono e aço inoxidável de forma a comparar as principais semelhanças e diferenças entre estes dois tipos de aços estruturais. O programa experimental possibilitou que conclusões significativas no comportamento a tração destas ligações pudessem ser observadas. Dentre outras variáveis que controlam estes estados limites últimos foi verificada a influência significativa da espessura da placa de aplicação do carregamento, disposição, configuração e número de parafusos da ligação e propriedades do aço inoxidável como ductilidade e razão entre suas tensões de escoamento e de ruptura.
The use of stainless steel in structural engineering applications is still seen by many architects and engineers as an extravagant solution. However attitude changes in the construction market and the natural transition to a sustainable development reducing environment impacts have boosted the use of stainless steel structures. A substantial majority of stainless steel structural design codes is still based on carbon steel analogies. Despite this fact the stainless steel presents four non-linear tension versus strain curves (tension and compression, parallel and perpendicular to the rolling direction) without a defined yield plateau snf strain hardening zones substantially altering its global structural response. The present investigation adopted the austenitic stainless steel grade 304 and the carbon steel USI300, both with similar yield stresses but with different tension stresses and ductility capacities. Structural elements subjected to tension axial forces usually presents the net section rupture as one of its controlling ultimate limit states. The present study performed an innovative experimental programme to evaluate and investigate the tension capacity of staggered bolted members. The experiments were made with carbon and stainless steels to compare and access their similarities and differences in terms of structural performance. The experimental results enable the observation of significant conclusion concerning the tension response of the investigated bolted staggered members. The controlling ultimate limit states were significantly influenced by various parameters like: the loading plate thickness, the layout, configuration and number of bolts adopted in the joint, and stainless steel properties like ductility capacity and the ratio between the yield and ultimate stresses.

As a valuable asset in human augmentation and medical rehabilitation, exoskeletons have become a major area for research and development. They have shown themselves to be effective tools for training and rehabilitation of individuals suffering from limited mobility. However, most exoskeletons are not capable of balancing without the assistance of crutches from the user. Leveraging technology and techniques developed for force controlled humanoid robots, a project was undertaken to develop a fully self-balancing, compliant lower-body robotic exoskeleton. Due to their many beneficial features, series elastic actuators were utilized to power the joints on the exoskeleton. This thesis details the development of four linear series elastic actuators (LSEA) as part of this project. All 12-degrees of freedom will be powered by one of these four LSEA's. Actuator requirements were developed by examining human gait data and three robot-walking simulations. These four walking scenarios were synthesized into one set of power requirements for actuator development. Using these requirements, analytical models were developed to perform component trade studies and predict the performance of the actuator. These actuators utilize high-efficacy components, parallel electric motors, and liquid cooling to attain high power-to-weight ratios, while maintaining a small lightweight design. These analyses and trade studies have resulted in the design of a dual-motor liquid-cooled actuator capable of producing a peak force 8500N with a maximum travel speed of 0.267m/s, and three different single-motor actuators capable of producing forces up to 2450N continuously, with a maximum travel speeds up to 0.767m/s.
Master of Science

The thesis contains the design and assessment of three-aisled steel building for small metal production. Supporting span of construction hall is 9, 18 and 9 m. In the middle wing is situated bridge crane with capacity of 2 tons. The estimated location of the object is Luhačovice. The initial design concept was specified by supervisor (as the idea of the investor/architect), for which was did static and structural solution and assembly details. For selected option was made a calculation of supporting structures and selected assembly details. The hall has a rectangular floor plan of 36x36m and ridge height is 9 m. The central wing is made of steel and side extensions are made of glued laminated timber.

The diploma thesis describes the design and assessment of steel structure of the roofing of the military museum in Králíky. The supporting structure of hall is 40.00 meters span. The total layout are 55.93 x 72.04 m, building height 11.43 m, 16.11 m pylon height. Main construction material is steel, grade S355, secondary constructions are made from steel grade S235, rods are made from steel grade S460. I did optimization of steel structure and chose the best option. For this option I made detailed structural analysis. It is prepared by static analysis of the main load-bearing parts of the structure, including joints and details. The supporting structure of hall consists in the transverse direction from the curved spatial lattice structure made of steel circular tubes which hang on rods on a sloped pylon. Part of the report is open-air roofing.

Etude d'un robot avec un prehenseur tridigital. Le manipulateur possede six degres de liberte et est dote d'un capteur tactile d'efforts a six composantes. Conception d'une commande gardee avec retour d'efforts. Etude d'un logiciel de strategie d'assemblage. Experimentation dans le cas de taches d'assemblage de haute precision

Problemes d'optimisation en conception assistee par ordinateur. Utilisation de la methode des elements finis. Application au contact entre deux dents d'engrenages, aux assemblages boulonnes et aux guidages en rotation (paliers)

The subject of the master´s thesis is the design and assessment of the static load-bearing steel structure office building. It is an eight-storey building with a floor plan and dimensions 54x15m. The proposal has three variants. In one of them a steel frame with a hinge attached elements. These are the pillars, beams, trusses, joists and purlins, which are coupled with trapeze plate and thereby secure the stability of the position in the horizontal direction. The steel structure is placed between the reinforced concrete towers.

Design of load bearing steel structure of a curling building. Examination of main load bearing building blocks. Examination of selected details. Drawing of disposition and selected details. Elaboration of manufactory drawings of chosen segments.

he master’s thesis consists of a case study of an observation tower design made of glue laminated timber and steel. There are two different tower shapes of anchored or free standing tower and these towers are compared. One of the design is chosen and elaborated into final detailing. A short review of main issues bound with the observation towers is given. The review deals mainly with loading (mainly priniples wind loads are analised) and evaluating of towers (ultimate limit states, service limit states and acceleration comfort). The height of final construction is up to 60m. The design is formed by a space lattice structure made of glue laminated timber and steel members of different class. The members are fastened mainly by means of dowel joints with slotted-in-plates . There is a light steel stairway inserted into the main structure.

The subject of master’s thesis is design and assessment of steel load-bearing construction of atypical family house in Vrchlabí. Structure is designed as multi-storey steel structure, cooperating with stiff concrete core. The design was considered in four different options which combines possibility of using steel, steel and timber with different way of stiffness for whole structure. There is also composite steel-concrete alternative floor trimmer for selected option. Design and assessment was conducted in accordance with the applicable standards and by using software Scia Engineer.

Aviation is known to have some of the most stringent structural health monitoring standards in the world. An example of this would be the fact that certain bolts in the aircraft assembly must be periodically removed and inspected for fatigue damage. This can be a very costly endeavour: a case in point being the Hercules C130 aircraft, which requires approximately 200 man hours of down-time for the inspection of the bolts that attach the wings to the fuselage. The substitution of TRIP (Transformation Induced Plasticity) steel bolts for the current HSLA steel (AISI 4340) from which the bolts are manufactured, allows the bolt to act in the capacity of load bearing member as well as damage detector. This unique feature is a consequence of the transformation characteristic exhibited by TRIP steels when they are strained: an irreversible change within their microstructure from paramagnetic austenite parent phase to permanent ferromagnetic state occurs in direct proportion to the peak strain. This property allows us to establish a relationship from which the service life of the component can be determined. A prototype of a smart aircraft bolt and washer system has been developed, where the bolt acts as damage detector and the washer effectively examines the health of the bolt by reading the changing magnetic susceptibility of the bolt. This study presents both material development and product development phases of the Smart Aircraft Bolt prototype. A prediction of transformation characteristic due to deformation is carried out using finite element analysis (mechanical model) and a constitutive model (strain induced martensitic transformation kinetics) to predict the best situation for the smart washer. In addition, experimental work is performed in the form of cyclic temperature testing (with and without external loading) and tension-tension fatigue testing. For both sets of experimental testing, two positions of washer placement are tested. A correlation between volume fraction of martensite present and remaining life, is therefore possible.
Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2008.

The investigation contained herein is a part of a larger, long-term project: The Development of SMART Aircraft Bolts. Structural failures, at highly stressed components, arc common in some of the aircraft used by the South African Air force. The strength of one such component, the wing bolts on the C-130 aircraft, is analysed and compared to the stress distribution in a bolt which has a small hole drilled through the centre of the bolt (which will be used to insert a sensing device). The results of this analysis will be used as input into further phases of the project, e.g., SMART material selection and the development of sensing devices. Due to the complex physics of a bolted joint, advanced analysis of the bolt under conservative loading was performed, after conducting thorough research into bolted joint design and analysis methods, in order to provoke the final recommendations.
Thesis (M.Sc.)-University of Natal, Durban, 2000.