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Recent studies showed the need for timber connections with high fire performance. Connections of members in timber structures commonly comprise steel connectors, such as dowels, screws, nails and toothed plates. However, multiple studies have shown that the presence of exposed metal in timber connections leads to a poor performance under fire conditions. Replacing metallic fasteners with non-metallic fasteners potentially enhances the fire performance of timber connections. Previous studies showed that Glass Fibre Reinforced Polymer (GFRP) dowels can be a viable replacement for steel dowels and that Densified Veneer Wood functions well as a flitch plate material. However, as the resin matrix of GFRP dowels is viscoelastic, connection creep, which is not studied before, can be of concern. Also no research has been carried out on the fire performance of these connections. Therefore, a study of the creep behaviour and the fire performance of non-metallic timber connections comprising GFRP dowels and a Densified Veneer Wood flitch plate was performed, as is discussed in this thesis. Predictive models were proposed to determine the connection slip and load bearing capacity at ambient and elevated temperatures and in a fire. The material properties and heat transfer properties required for these models were determined experimentally and predictions of these models were experimentally validated. Furthermore, an adjustment of the predictive model of connection slip at ambient temperature allowed approximating the creep of the connection. The material properties, required for the creep model, were determined experimentally and predictions of the model were compared to results of longterm connection tests. The study confirmed that timber members jointed with non-metallic connectors have a significantly improved fire performance to timber joints using metallic connections. Models developed and proposed to predict fire performance gave accurate predictions of time to failure. It was concluded that non-metallic connections showed more creep per load per connector, than metallic connections. However, the ratio between initial deflection and creep (relative creep) and the ratio between load level and creep were shown to be similar for metallic and non-metallic connections.

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The diploma thesis deals with the study of Inter-Laminar Shear Strength (ILSS) of polymer composites, based on unsaturated polyester resin with unidirectionally oriented basalt or glass fibers. The basis of the experimental part is the preparation of composite samples with different types of surface treatment of a fibers (a reinforcement) as well as the surface treatment itself. The untreated, the commercially treated fibers and the plasmatreated fibers used as reinforcement in the polymer composites were analysed by a short beam shear test and their ILSS was determined. The effect of various deposition conditions during Plasma-Enhanced Chemical Vapour Deposition (PECVD) on the value of ILSS of the composite with originally unsized glass or basalt fibers was studied. The impact of aging on the interlaminar shear strength of the composites was investigated for commercially treated glass fibers. The Scanning Electron Microscopy (SEM) is also used in the thesis together with the Energy Dispersive Spectroscopy (EDS). Based on all the results a proposal was made to correct and improve the deposition conditions and thus improve the interphase to achieve the required shear properties of polymer composites.

Diploma thesis is aimed at deposition of thin films on glass fibers using plasma-enhanced chemical vapor deposition from tetravinylsilane as a monomer. Such surface modified glass fibers were used as reinforcements for fabrication of polymer composites with unsaturated polyester resin as a matrix. Chemical and optical properties of prepared thin films were characterized using infared spectroscopy and spectroscopic ellipsometry. An influence of deposited thin films on the shear strength of composite material was observed using short-beam shear test.

Packages are the means of preservation, distribution and convenience of use for food, medicine and other consumer products. Package opening is becoming complicated in many cases because of cutting cost in design and production of opening techniques. Introduction of new package opening technique, material or geometry for better opening experience, forces new design measurements which require a large number of prototype developments and physical testing. In order to achieve more rapid and accurate design, Finite Element Method (FEM) Simulations are widely used in packaging industries to compliment and reduce the number of physical testing. The goal of this work is to develop the building blocks towards complete package opening simulation. The study focuses on testing and simulation of shear fracture and shear delamination of packaging materials. A modified shear test specimen was developed and optimized by finite element simulation. Test method was validated for High-density polyethylene (HDPE) and Polypropylene (PP). The developed method has been accepted by international standards organization ASTM. Based on linear elastic fracture mechanics, a geometry correction factor of shear fracture toughness for the proposed specimen was derived. The study concluded that, for ease of opening, HDPE is a more favorable material for screw caps than PP. When performing the experiment with the shear specimen to find essential work of fracture, the ligament length should be varied between twice of the thickness and half of the width of the specimen ligament. Multi-layered thin laminate of Low-density polyethylene (LDPE) and aluminum (Al), also known as Al/LDPE laminate, is another key object addressed in this study. Continuum and fracture testing of individual layers provided the base information and input for numerical modeling. The propagation of an interfacial pre-crack in lamination in Al-LDPE laminate was simulated using several numerical techniques available in the commercial FEM solver ABAQUS, and it was concluded that using the combination of VCCT technique to model the interfacial delamination and coupled elasto-plastic damage constitutive for Al and LDPE substrates can describe interfacial delamination and failure due to necking. It was also concluded that the delamination mode in a pre-crack tip is influenced by the ratio of fracture energy release rate of mode I and II. To address the challenge in quantifying shear energy release rate of laminate with very thin substrate, a convenient test technique is proposed. Additionally, scanning electron microscopic study provided useful information on fractured and delaminated surfaces and provided evidence that strengthened the conclusions of this work. The proposed test methods in this work will be crucial to measure the shear mechanical properties in bulk material and thin substrates. Laminates of Al and LDPE or similar material can be studied using the developed simulation technique which can be effectively used for decision support in early package development.

Cieľom diplomovej práce je príprava polymerných kompozitov vyztužených sklenenými vláknami s riadenou medzifázou za použitia metódy plazmochemickej depozície z plynnej fáze a monomeru tetravinylsilanu. Teoretická časť je zameraná na literárnu rešerš o plazme, plazmovej polymerácií, tenkých vrstvách a kompozitoch. Experimentálna časť popisuje použité materiály a aparaturu použitú na povrchovú modifikáciu sklenených vlákien a prípravu vláknom vyztužených kompozitov. Povrchová úprava sklenených vlákien prebiehala za rôznych depozičných podmienok. Chemické a mechanické analýzy vytvorenej medzivrstvy prebiehali za použitia FTIR spektrometrie a vrypového testu. Vliv povrchovej úpravy bol zistený pomocou získanej interlaminárnej šmykovej sily použítím testu krátkych trámečkov.

Experimentation exploring the movement of voids within carbon fiber reinforced plastics was performed using fluorescent dye infused into the laminates observed through a transparent mold under ultraviolet light. In situ photography was used as an inspection method for void content during Resin Transfer Molding for these laminates. This in situ inspection method for determining the void content of composite laminates was compared to more common ex-situ quality inspection methods i.e. ultrasonic inspection and cross-section microscopy. Results for localized and total void count in each of these methods were directly compared to test samples and linear correlations between the three test methods were sought. Test coupons were then cut from these laminates and were used to calculate the interlaminar shear strength at certain locations throughout the laminates. Although this research did not adequately observe correlations between results obtained from ultrasonic C-scans, cross-sectional microscopy and in situ photography of the surface, it was seen that the fluid dynamics of the thermosetting epoxy used in this experimentation correlated to results obtained from previous experimentation performed by students at Brigham Young University using vegetable oil as a substitute for resin.

[pt] Materiais compósitos pultrudados poliméricos reforçados com fibra de vidro (PRFV) são aplicados em diversos setores da indústria por apresentarem boas resistências mecânicas, baixo peso específico e alta resistência à corrosão. A exposição a ambientes agressivos tais como imersão em água, condicionamento sob alta umidade relativa, temperatura baixa e elevada, ciclos térmicos e úmidos, bem como a combinação desses efeitos, tornou-se cada vez mais objeto de estudo para esses tipos de materiais. A compreensão dos efeitos das condições ambientais no comportamento do material é essencial para avaliar seu desempenho e, desta forma, garantir a segurança necessária ao projeto estrutural. Com o objetivo de compreender melhor a influência de diferentes condições ambientais nas propriedades do material compósito PRFV, foram estudados os efeitos da temperatura e umidade, além da ação combinada dessas duas condições, nas suas propriedades físicas, químicas, térmicas e mecânicas. Neste estudo, foram levados em conta aspectos importantes que influenciam o comportamento do material, como a resina utilizada, o grau de cura, e características químicas e físicas do material. Os ensaios experimentais foram conduzidos em quatro condições ambientais: (i) exposição a temperaturas moderadas/elevadas (70 graus C à 330 graus C), (ii) imersão em água deionizada (25 graus C, 55 graus C e 70 graus C), (iii) exposição à névoa salina em câmaras de envelhecimento higrotérmico (35 graus C, 55 graus C e 70 graus C), e (iv) exposição a ambiente externo real. Além disso, foram aplicados modelos teóricos para avaliação dos resultados. Foi observado que a temperatura, o tempo de condicionamento e a umidade são fatores preponderantes no comportamento do material. Adicionalmente, uma questão importante para o estudo de pultrudados reside na compreensão das propriedades interlaminares do material. Nesse contexto, a fratura interlaminar, associada às fissuras no plano longitudinal entre as camadas do material, é uma das principais causas de falha em compósitos pultrudados. Consequentemente, a análise da fratura em modo II, que avalia o mecanismo da propagação da fissura no plano interlaminar, vem ganhando espaço no estudo de materiais compósitos. A análise de fratura em modo II não é trivial ou normatizada para compósitos pultrudados PRFV, de forma que poucos dados e conclusões efetivas foram obtidos até o momento a esse respeito. Com o objetivo de suprir essa lacuna, realizou-se uma extensa investigação experimental, culminando na proposição de uma nova metodologia para avaliação da fratura em modo II em materiais compósitos poliméricos pultrudados reforçados com fibra de vidro (PRFV). / [en] Pultruded glass-fiber reinforced polymer (GFRP) composites are applied in various industrial sectors due to their good mechanical strength, low specific weight, and high resistance to corrosion. Exposure to aggressive environments has become an increasingly studied topic for these materials, such as immersion in water, conditioning under high relative humidity, low and high temperatures, thermal and humid cycles, as well as the combination of these effects. Understanding the effects of environment condition on material behavior is essential to evaluate its performance and ensure the necessary safety for structural design. In order to better understand the influence of environmental conditions on the properties of GFRPs, the effects of temperature and humidity, as well as the combined action of these two effects, on their physical, chemical, thermal, and mechanical properties were studied. Important aspects that influence the material s behavior were considered, such as the resin used, the degree of curing, and the chemical and physical characteristics of the material. Experimental tests were conducted under four environmental conditions: (i) exposure to moderate/high temperatures (70 degrees C to 330 degrees C), (ii) immersion in deionized water (25 degrees C, 55 degrees C, and 70 degrees C), (iii) exposure to salt spray in hygrothermal aging chambers (35 degrees C, 55 degrees C, and 70 degrees C), and (iv) exposure to real outdoor environment. In addition, theoretical models were applied to evaluate the results. It was observed that temperature, conditioning time, and moisture are predominant factors in material behavior. Additionally, a important issue for the study of pultruded composites lies in understanding the interlaminar properties of the material. In this context, interlaminar fracture, associated with longitudinal cracks between the layers of the material, is one of the main causes of failure in pultruded composites. Consequently, mode II fracture analysis, which evaluates the mechanism of crack propagation in the interlaminar plane, has been gaining ground in the study of composite materials. Mode II fracture analysis is not trivial or standardized for pultruded GFRP composites, so few data and effective conclusions have been obtained in this regard so far. In order to fill this gap, an extensive experimental investigation was carried out, culminating in the proposal of a new methodology for evaluating mode II fracture in pultruded GFRPs.