Контролируемые прочностные показатели для различных видов мебели

Методические указания по курсам «Расчет конструкций изделий из древесины и испытания мебели», «Технология изделий из древесины» для выполнения практических и лабораторных работ обучающимися по направлениям 35.03.02, 35.04.02 «Технология лесозаготовительных и деревоперерабатывающих производств», профиль «Технология деревообработки

Sustainable and multifunctional composites of graphene-based natural jute fibers

Smart and sustainable natural fiber‐based composites are of great interest due to their biodegradability, recyclability, and environmental benefits over synthetic fiber composites. In addition, the environmental impact of plastics and synthetic fibers are widespread and substantial, as they can stay in the environment for hundreds of years and contribute significantly to global carbon emissions. Natural fibers such as jute can potentially replace synthetic fibers to manufacture environmentally sustainable, biodegradable, and lightweight composites with improved properties, good thermal and acoustic insulation, and a smaller carbon footprint. However, natural jute fiber‐based composites suffer not only from poor mechanical properties but also being inherently electrically insulating, which limits their applications as multifunctional composites. Here multi‐functional and environmentally sustainable smart composites of graphene‐based natural jute fibers with excellent tensile and interfacial properties are reported. The reduced graphene oxide‐based natural jute fiber enhance the Young's modulus of the composites by ≈450%, and tensile strength by ≈183% after physical and chemical treatment. Such high‐performance composites can also be used as multifunctional smart composites, as demonstrated by effective electro‐magnetic interference shielding performance. This may lead to manufacturing of next generation smart, strong, and sustainable natural fiber composites for high performance engineering applications without conferring environmental problems

Thermal protection of carbon fiber-reinforced composites by ceramic particles

The thermal barrier efficiency of two types of ceramic particle, glass flakes and aluminum titanate, dispersed on the surface of carbon-fiber epoxy composites, has been evaluated using a cone calorimeter at 35 and 50 kW/m2, in addition to temperature gradients through the samples’ thicknesses, measured by inserting thermocouples on the exposed and back surfaces during the cone tests. Two techniques of dispersing ceramic particles on the surface have been employed, one where particles were dispersed on semi-cured laminate and the other where their dispersion in a phenolic resin was applied on the laminate surface, using the same method as used previously for glass fiber composites. The morphology and durability of the coatings to water absorption, peeling, impact and flexural tension were also studied and compared with those previously reported for glass-fiber epoxy composites. With both methods, uniform coatings could be achieved, which were durable to peeling or water absorption with a minimal adverse effect on the mechanical properties of composites. While all these properties were comparable to those previously observed for glass fiber composites, the ceramic particles have seen to be more effective on this less flammable, carbon fiber composite substrate

Vibration Measurement for Rotatory Machines : Importance of maintenance practices

This thesis work was done in cooperation with Hi-Tekno Engineering and consulting office. The purpose of this thesis was to demonstrate the importance of vibration measurements in modern day production systems. The aim was to explain how vibration measurements are performed in the field and what kind of machinery diagnosis can be achieved. Effective maintenance services in the production systems of today are vital for any company as to the profitability figures. Vibration measurements give the user a clear picture of the machines condition, by this is easier to plan the maintenance schedule, focusing the resources only on those machines that have signs of failures. A vibration analysis is about the art of looking for changes in the vibration pattern, and then relating those changes back to the machines mechanical design. The level of vibration and the pattern of the vibration tell us something about the internal condition of the rotating component. The vibration pattern can tell us if the machine is out of balance or out of alignment. Also faults with the rolling elements and coupling problems can be detected. The practical work in this project was conducted in Karkkila at the heating system plant of the municipality. I measured the vibration levels for the flue gas fan. The flue gas fan removes the gases generated in the combustion boilers, after which they have passed through a filter and are directed back into the atmosphere. The outcome demonstrated that there was a bearing problem in the flue gas fan and it was starting to develop

Reprocessed Materials Used in Rotationally Moulded Sandwich Structures for Enhancing Environmental Sustainability: Low-Velocity Impact and Flexure-after-Impact Responses

In the rotational moulding industry, non-used, scrap, and waste purge materials have tremendous potential to be reprocessed and applied in skin-foam-skin sandwich structures to replace and reduce the use of virgin polymers. This approach not only encourages the re-use of these waste materials but also significantly contributes to reduce environmental impacts associated with the use of virgin polymers in this sector. The demand of rotationally moulded sandwich structures is rapidly increasing in automotive, marine, and storage tanks, where investigating their impact and after-impact responses are crucial. Hence, this study investigated the low-velocity impact (LVI) and flexure-after-impact (FAI) responses of rotationally moulded sandwich structures manufactured using reprocessed materials. Results obtained from LVI induced damage at two different incident energy levels (15 J, 30 J), and the residual flexural strength of impacted structures evaluated by three-points bending tests were compared with non-reprocessed sandwich structures (virgin materials). The impact damage progression mechanism was characterized using the X-ray micro-computer-tomography technique. Reprocessed sandwiches demonstrated 91% and 66% post-impact residual strength at 15 J and 30 J respectively, while for non-reprocessed sandwiches, these values were calculated as 93% and 88%. Although reprocessed sandwich structures showed a lower performance over non-reprocessed sandwiches, they have a strong potential to be used in sandwich structures for various applications

Improved mechanical properties of environmentally friendly jute fibre reinforced metal laminate sandwich composite through enhanced interface

Natural plant based fibres are being increasingly used in sustainable fibre reinforced composite applications in order to meet the demand of using environmentally friendly materials for composites. Fibre metal laminates (FMLs) are used in aerospace, automobile, marine and civil engineering applications, due to their excellent mechanical behaviors compared to traditional metals and their alloys. This study describes a novel fabrication of jute fibre reinforced aluminum metal laminates, using different jute fibre architectures (plain and twill fabric structures), wherein jute fibres were used in the skins and aluminum in the core layers. Jute fibres and aluminum sheets were chemically treated to enhance the compatibility and interfacial bonding at fibre-metals-matrix interfaces. FMLs were manufactured by hot pressing technique, after the application of wet lay-up process for the resin impregnation and they were further tested under tensile, flexural and impact loading conditions. While comparing results, the twill architecture showed improved tensile and flexural properties compared to plain fabric based FMLs. Chemical treatments on twill jute fibres and metal sheets further exceptionally enhanced the flexural properties (151 MPa flexural strength and 21.3 GPa modulus and they were increased by 186.5 % and 722.7 % respectively compared to the untreated jute fibre counterparts) of the laminates due to a significant improvement in the adhesion between the jute fibre and aluminum sheet after alkali treatment applied. Therefore, with these enhanced properties, jute based FML laminates can be used as sustainable composite materials in many structural applications