The space environment presents various challenges when designing systems and selecting materials for applications beyond Earth’s atmosphere. For mission success, these challenges must be considered. One of the detrimental aspects of the space en- vironment is Atomic Oxygen, AO. Only present in harmful quantities in Lower Earth Orbit, LEO, AO causes significant damage to materials by breaking molecular bonds. California Polytechnic State University’s, Cal Poly’s, space environments laboratory features an apparatus capable of simulating this environment. Very thin or short samples were tested to observe the mass loss due to erosion of the sample material. Recent modifications to the system allow it to expose surfaces of three dimensional objects to AO rather than only those two dimensional objects. Simulating this effect on taller samples makes available the opportunity to test coupons that are then used in additional testing to measure the effect of that erosion on other properties. Challenges in adapting the AO system are explored and addressed, as well as some possible use cases for future work. As a use case, bending moment specimens were exposed to AO prior to testing in four point bending. Multiple regression models were constructed to determine variables contributing to slope changes between specimen pairs’ linear-elastic regions of force-displacement graphs. Results show that AO exposed specimens had significantly gentler slopes in the linear elastic region of the force-displacement curve, meaning that AO exposure reduced structural rigidity of the coupons.

Present day composite sandwich panels provide incredible strength. Their largest problem, however, is early bonding failure between the core and the skin. This is due to the low bonding surface area of present cores like honeycomb. Corrugated structures could provide a remedy for this with their much larger bonding surface area. Corrugated structures have extreme mechanical properties deeming them particularly useful in aerospace and automotive applications. However, previous research has shown that the stiffness of carbon fiber causes debonding and drastic failure when used as both a core and a skin. Bio-composites have properties that could strengthen the corrugated sandwich panel against such debonding and increase the strength of the structure while making it cheaper and more environmentally friendly. This thesis presents the optimum design, manufacturing, and testing of corrugated sandwich panel structures with integrated bio-composites under edgewise compression loading. To do this, optimum corrugation geometry was identified using theoretical analysis of the moment and bonding area of the shape. Control tests with carbon fiber and hemp were conducted. The bio-composite was integrated in both the core and the skin individually in corrugated sandwich panels. The cases tested were all-carbon fiber, hemp skin with carbon fiber core, carbon fiber skin with hemp core, and all-hemp. These corrugated structures were analyzed by conducting compression loading tests on varying lengths of single-ligament panels utilizing trapezoidal corrugation as the core and a flat plate as the skin. The lengths tested were 1, 2, 3, and 4 inches. As many samples as possible were manufactured out of limited material with heavier focus on creating the shorter samples. The goal of this testing was, first, to determine if hemp fibers were viable as a substitute for certain sections of the traditional composite structure, and second, to see if integrating hemp fibers would solve the problems of debonding seen in the all-carbon fiber samples seen in previous research. To determine mechanical property viability, the ultimate load and stiffness were investigated for each sample, as well as investigation of the failure modes seen in the test. Secondary goals were to see at what length buckling behavior became an issue and to see if this corrugated structure and all its failure modes could be simulated in finite element analysis. At the 1-inch and 2-inch lengths where minimal buckling was encountered, the hemp core-carbon skin samples showed better results than both the all-carbon fiber and the all-hemp samples with a 4% and 6% increase in average ultimate load and a 11% and 47% increase in stiffness, respectively. From these results, it was concluded that hybrid bio-composite structures can have comparable mechanical properties to traditional composites and can solve bonding failure.

This work deals with composite sandwich panels, which are currently used as supporting structures for satellites. This type of panel contains an aluminum honeycomb core and two thin laminate coatings, reinforced with carbon fibers. Laminate sandwich panel coatings offer an alternative to conventional aluminum coatings, which is advantageous mainly due to the reduction of weight and increase of the flexural stiffness of the panels. The work is a parametric study of mechanical properties for several variants of the coating of sandwich panels. These are laminate coatings, differing in the orientation of the fibers in the individual layers, as well as an aluminum alloy coating. The study is divided into two parts. The first part examines the deformation-stress response of a sandwich panel, which is simply supported at the edges and loaded with pressure. The response calculation is performed using FEM and verified by the method of sum of an infinite series. The second part investigates the deformation-stress response of the joint, (node) of two sandwich panels, which is loaded by random vibrations, aimed at simulating the mechanical environment of the rocket carrier during the takeoff of the launch vehicle. The response is calculated using FEM and verified by an experiment on a vibrating stool for a selected variant of the laminate coating of sandwich panels. The results of the work can be used for the design of baffle of the X-ray imaging device (SXI), which is part of the equipment of the space satellite of the SMILE project.

Cílem práce bylo vyvinout vložku se speciálními mechanickými vlastnostmi pro satelitní strukturu ze sendvičových panelů. Problém byl analyzován a byla navržena inovativní konstrukce vložky založená na existující aplikaci, přičemž byla brána v potaz proveditelnost výroby. Návrh byl ověřen pomocí metody konečných prvků. Práce se také zabývá technologickým návrhem výroby vložky. Nakonec byla představena metodologie zkoušky pro ověření návrhu vložky.

This diploma thesis deals with an alternative frame design of Formula Student which is made of aluminium honeycomb sandwich. First part describes the current options analysis, the property of aluminium panel and its loading behaviour. Next part provides a frame design and computational model for stress analysis by FEM and the main part is contains the calculation of torsional rigidity including its procedure. Finally, the thesis provides the comparison with tubular space frame of the 3th generation formula Dragon.

Master thesis is focused on proposal of improved manufacturing process of assembly named "sandwich" produced in Iveco bus company. There is solved new fixation of assembly bench, replacement of currently used glues and material of ledge as well. In the first part there is company introduction Iveco Bus. Second part consist of construction analysis and description of present manufacturing process. Further there is introduction, solving out of thesis topics and proposal of new manufacturing process is written. At the end of thesis are attached comparison between present and proposed manufacturing process.

A parametrical study is performed of coolant dump gas ejectors for a sandwich rocket nozzle design. Five geometrical variations are simulated in four ambient conditions (static, subsonic, supersonic, vacuum) using an in-house CFD solver. The test cases are compared with a baseline case and the resulting thrust and ISP are evaluated on a local and global level. A longer dump wall is found to give the best performance in all ambient cases, with a second possibility of reducing the circumference of the nozzle end stiffener. The possibility of post-ejection coolant gas combustion is encountered for high ambient pressure, high subsonic velocity flight.

Drywall board-based structures, a competent and cost-effective method of providing flexible partitioning assemblies in commercial and residential houses, are now widely used as walls or ceilings. However, the gypsum-based drywall that has been used in construction is not water-resistant and can create problems such as mold growth and structural defects. The aim of this study is 1) to develop a new sandwich panel with better physical and mechanical properties using locally sourced materials 2) to investigate the long-term hygrothermal performance of the new sandwich panel through using a numerical simulation. The sandwich panel is composed of two different thicknesses of kraft-paper honeycomb core bonded to two cementitious panels with silicone-based adhesive. The experimental results show that the sandwich panel with a thicker core has lower thermal conductivity and higher flexural strength compared to the gypsum-based drywall. The heat and moisture performance of two wall structures were performed using the WUFI Pro simulation program. The results of the modeling analysis present that wall assembly with gypsum-based drywall has higher water content than multilayer sandwich panel. In addition, the multilayer sandwich panel shows a 4.6% lower annual heat flow compared to the reference wall.

In this thesis project a concrete sandwich wall element of 250 mm insulation of Kooltherm has been resulted to have U-values and ψ-values closer to the passive housing recommendations. However, by using 180 mm thick insulation, no significant difference in the annual energy consumption is observed. Using a metal sheet in the window connection and small concrete brackets, low thermal bridge values are achieved. Low thermal bridge coefficient values were also observed with thick insulation in the foundation and the roof structure, although, it is impossible to achieve values below 0,01 W/mK in the corner connections. Airtightness of the building envelope is more important than the thickness of the wall in the energy consumption simulations. Therefore, the thermal bridging and the U-values of the wall are, in most cases, dependent on the thickness of the element. No conclusions on the structural reliability of the solutions can be extracted from this thesis project. In order to conclude the statements above, this thesis project has been focused on the evaluation and design of a concrete sandwich wall panel. The design of the wall element, including its reinforcement and connectors, while achieving values according to passive housing regulations, is the initial goal of this project. Subsequently, connections between the building components and the wall element are analyzed and designed through several simulations according to the passive housing regulations respectively. Simulation tests took place in Sweco Structures AB offices with the valuable contribution of experts. An existing building project was used and evaluated in order to present the simulation results in a more realistic manner. Several insulation materials have been tested for the thermal and moisture reliability. Using the existing building as a base for information, energy simulations generated the energy consumption results in order to compare different wall thicknesses, and thermal bridging effects. This project is inspired by the needs of building sustainability and efficiency, which has become a significant part of the worldwide effort on reducing the energy consumption on the planet. Regulations regarding building technology have been completely changed and adjusted in the passive housing design. Particular effort has been put on the commercial and multi-residential buildings, in which the energy consumption is usually higher than in small family houses. Concrete sandwich wall panels have been introduced in the building market as an alternative and more efficient way of constructing. Prefabrication has been proved to be less time consuming, although issues on the thermal behavior appear in this kind of structure. The evaluation of the thermal efficiency of the concrete sandwich wall elements has been a significant issue in the civil engineering society and research.

Over the past century, the automobile has become an integral part of modern industrializedsociety. Consumer demands, regulatory legislation, and the corporate need togenerate a profit, have been the most influential factors in driving forward the evolutionof the automobile. As the comfort, safety, and reliability of the automobile haveincreased, so has its complexity, and most definitely its mass.The work within this thesis addresses the twofold problem of economy and ecologywith respect to sustainable development of automobiles. Specifically, the conflictingproblems of reducing weight, and maintaining or improving noise, vibration, andharshness behaviour are addressed. Potential solutions to these problems must also beexecutable at the same, or preferably lower production costs. The hypothesis is that byreplacing acoustic treatments, aesthetic details, and complex systems of structural componentsboth on the interior and exterior of the vehicle with a single multi-functionalbody panel, functionality can be retained at a reduced mass (i.e. reduced consumptionof raw materials) and reduced fiscal cost.A case study is performed focusing on the roof structure of a production vehicle. Fullvehicle and component level acoustic testing is performed to acquire acoustic functionalrequirements. Vibro-mechanical testing at the component level is performedto acquire structural functional requirements complimentary to those in the vehiclesdesign specifications. Finite element modelling and analysis is employed to createa model representative of the as-tested component and evaluate its acoustic and mechanicalbehaviour numerically. Results of numerical simulations are compared withthe measured results for both acoustic and mechanical response in order to verify themodel and firmly establish a set of acoustic and mechanical constraints for future work.A new, multi-layered, multi-functional sandwich panel concept is proposed which replacesthe outer sheet metal, damping treatments, transverse beams, and interior trimof the existing structure. The new panel is weight optimized to a set of structural constraintsand its acoustic properties are evaluated. Results show a significant reductionin mass compared to the existing system with no degradation of the acoustic environment.A discussion of the results is presented, as is a suggestion for future research.