Restoration of Structural Timber Elements Using Epoxy Resin: Analysis of Mechanical Properties

2013 ◽  
Vol 778 ◽  
pp. 582-587 ◽  
Author(s):  
Marília da Silva Bertolini ◽  
Laurenn Borges de Macedo ◽  
Diego Henrique de Almeida ◽  
Felipe Hideyoshi Icimoto ◽  
Francisco Antonio Rocco Lahr
Keyword(s):  
Cultural Heritage ◽  
Epoxy Resin ◽  
Structural Integrity ◽  
Mechanical Performance ◽  
Structural Characteristics ◽  
Conservation Status ◽  
Wood Properties ◽  
Structural Timber ◽  
Structural Elements ◽  
Structural Shocks

Brazil cultural heritage is composed by numerous constructions that describe the various historical periods lived by country. Constructions arent in good conservation status, showing systematically some deterioration level of their structural elements, among them those of wood. Restoration process aims to preserve the identity of original cultural heritage. It is essential maintain structural characteristics related to mechanical loads response which are closely dependent on wood properties avoiding possible structural shocks. Wood deterioration can be characterized by fungi decay or termite attack. Depending on level and position of the deteriorated area in structural set, local interventions are enough to maintain structural integrity. Polymeric resins are material options that can be used when removed these deteriorated regions, requiring compatibility with wood to maintain structural elements properties. This paper aims use of a technical for restoring structural timber from historic buildings, based on removal of decayed regions and filling them with epoxy resin. To analyze restoration effectiveness, properties in static bending, according to Brazilian standard, were determined. Samples were produced containing one and three restorations along the specimens (105 cm in length and nominal square cross section of 4.5 cm side), on the same side. Samples of Pinus taeda with gaps generated in the specimens with dimensions of 1.10 cm in depth and 8 cm in length were tested, with restorations placed in central region. For grafting of these gaps bicomponent epoxy resin was employed, prepared by mixing components in 1:1.5 proportions. Resin was injected into splices and its cure occurred in a seven days period, using methodology restoration to simulate a situation in which these structural elements have been used. Samples were requested in static bending to obtaining the product of inertia, analyzing the amendment under the aspect of tractioned and as well under compressed edge. It is observed the viability of restoration using filling epoxy resin in timber samples, considering the mechanical performance and practicality of the methodology for local keeping.

scholarly journals The Plaka Bridge in Epirus: An Evaluation of New Building Materials for Its Restoration

Heritage ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 1136-1159
Author(s):  
Maria Apostolopoulou ◽  
Ioannis Nikolaidis ◽  
Iakovos Grillakis ◽  
Myrto Kalofonou ◽  
Vasileios Keramidas ◽  
...  
Keyword(s):  
Cultural Heritage ◽  
Heavy Rainfall ◽  
Building Materials ◽  
Structural Integrity ◽  
Mechanical Performance ◽  
Building Stone ◽  
Historical Building ◽  
Historical Materials ◽  
Important Landmark

The sustainable preservation of monuments requires the use of performing materials which are at the same time compatible with the monument’s historical building materials to ensure structural integrity, adequate performance of the structure in earthquake stresses, and resilience of both restoration and historical materials. This is especially true for cultural heritage assets that have experienced major destruction, demanding extensive reconstruction. The Plaka Bridge in Epirus, Greece, partially collapsed after a heavy rainfall in 2015. It was a supreme example of traditional stone bridge architecture of the region and an important landmark. In the present study, a potential restoration stone from a nearby quarry was examined in terms of compatibility in relation to the dominant historical building stone of the bridge, as well as in terms of mechanical performance, through a variety of in lab techniques. In addition, criteria were set for restoration mortars, taking into account the characteristics of the historical materials, as well as the environment of the bridge. The results of the study regarding the restoration stone and mortars are presented and assessed, in order to select the most appropriate restoration materials for Plaka Bridge in its upcoming restoration, aiming to enhance the overall resilience of the structure.

scholarly journals SMA-Coated Aluminum Structural Elements with Enhanced-Thermo-Mechanical Performance

2018 ◽  
Vol 27 (4) ◽  
pp. 096369351802700
Author(s):  
D.A. Exarchos ◽  
P.T. Dalla ◽  
I.K. Tragazikis ◽  
K.G. Dassios ◽  
C. De Crescenzo ◽  
...  
Keyword(s):  
Stress Field ◽  
Shape Memory ◽  
Structural Integrity ◽  
Mechanical Performance ◽  
Thermomechanical Properties ◽  
Structural Elements ◽  
Two Phase ◽  
Treatment Conditions ◽  
Local Reduction ◽  
Box Structure

This work presents the development of novel multifunctional Shape Memory Alloy (SMA) coatings aiming to improve the mechanical behavior of structural components, as well as their corrosion resistance. The groundbreaking concept of the new coating material is described briefly as follows: Upon heating, the SMA coating tends to recover its experienced deformation and return to its original shape. At that point, shear forces developing at the interface between coating and structure are expected to mitigate the deformation of the structure and reduce its overall stress field level. The latter is a great benefit for regions where cracks exist, since the local reduction of the stress field will delay the crack propagation and hence the structural failure. Numerical analysis is performed to gain understanding of the expected thermomechanical response of the entire SMA-coated composite structure. The influence of the alloy composition and precipitates on the thermomechanical properties are also examined. The SMA coating is subjected to appropriate processing conditions and deposited on metallic substrates of proper geometry following a custom-designed two-phase process, which enables beneficial shape recovery enabling the efficient mitigation of the structure's deformation. Processing consists of aging heat treatments, which are of paramount importance for endowing the coating with the shape memory effect. The effect of heat treatment conditions on the thermo-mechanical fatigue response of the material was also characterized. The developed SMA coatings on aluminum structural elements can find significant application in aeronautical engineering, as for example in the aircraft wing box structure reinforcement and the fuselage structure to enhance their structural integrity.

scholarly journals Impulsive Tests on Historical Structures: The Dome of Teatro Massimo in Palermo

2016 ◽  
Vol 10 (1) ◽  
pp. 122-135 ◽  
Author(s):  
Mario Di Paola ◽  
Francesco Lo Iacono ◽  
Giacomo Navarra ◽  
Antonina Pirrotta
Keyword(s):  
Structural Characteristics ◽  
Historical Memory ◽  
Conservation Status ◽  
Dynamic Monitoring ◽  
Structural Elements ◽  
Historical Building ◽  
Structural Dynamic ◽  
Historical Structures ◽  
Material State ◽  
Historical Past

Cultural heritage is the set of things, that having particular historical cultural and aesthetic are of public interest and constitute the wealth and civilization of a place and its people. Sharpen up methodologies aimed at safeguarding of monuments is crucial because the future may have in mind the historical past. Italy is a country that has invested heavily on its historical memory returned in large part by the historical building or the monuments. Furthermore, culture represents a fundamental indicator of the growth of the culture of a country. Consider a monitoring project of one of the most Impressive theater in the world, like “Teatro Massimo” in Palermo (Italy), means to add value to both of the issues mentioned above. Among several methods providing useful information about the conservation status of the structures, dynamic monitoring techniques are suitable to check and restore the global behavior of the buildings. The anomalous features diagnosis of the structural dynamic response is an index of alterations of the material state and, in the worst cases, is related to the presence of damaged structural elements. The present paper assesses, through a real investigation, the importance of dynamic tests on historical buildings. In particular impulsive tests return the main structural characteristics describing the current behaviour. Such tests are then crucial for updating numerical evaluation and check the need of restoring original main features or not, suggesting a strategy of restoration as well.

scholarly journals Enhanced Tensile Strength of Monolithic Epoxy with Highly Dispersed TiO2-Graphene Nanocomposites

2021 ◽  
Vol 5 (7) ◽  
pp. 191
Author(s):  
Yanshuai Wang ◽  
Siyao Guo ◽  
Biqin Dong ◽  
Feng Xing
Keyword(s):  
Tensile Strength ◽  
Epoxy Resin ◽  
Mechanical Performance ◽  
Chemical Properties ◽  
High Mechanical Property ◽  
Graphene Nanocomposites ◽  
Highly Dispersed ◽  
Dispersion State ◽  
Physical And Chemical

The functionalization of graphene has been reported widely, showing special physical and chemical properties. However, due to the lack of surface functional groups, the poor dispersibility of graphene in solvents strongly limits its engineering applications. This paper develops a novel green “in-situ titania intercalation” method to prepare a highly dispersed graphene, which is enabled by the generation of the titania precursor between the layer of graphene at room temperature to yield titania-graphene nanocomposites (TiO2-RGO). The precursor of titania will produce amounts of nano titania between the graphene interlayers, which can effectively resist the interfacial van der Waals force of the interlamination in graphene for improved dispersion state. Such highly dispersed TiO2-RGO nanocomposites were used to modify epoxy resin. Surprisingly, significant enhancement of the mechanical performance of epoxy resin was observed when incorporating the titania-graphene nanocomposites, especially the improvements in tensile strength and elongation at break, with 75.54% and 176.61% increases at optimal usage compared to the pure epoxy, respectively. The approach presented herein is easy and economical for industry production, which can be potentially applied to the research of high mechanical property graphene/epoxy composite system.

scholarly journals Computational and experimental mechanical performance of a new everolimus-eluting stent purpose-built for left main interventions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Saurabhi Samant ◽  
Wei Wu ◽  
Shijia Zhao ◽  
Behram Khan ◽  
Mohammadali Sharzehee ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Mechanical Performance ◽  
Experimental Studies ◽  
Patient Specific ◽  
Wall Structure ◽  
Left Main ◽  
Element Analysis ◽  
Stent Expansion ◽  
Radial Strength ◽  
Different Diameters

AbstractLeft main (LM) coronary artery bifurcation stenting is a challenging topic due to the distinct anatomy and wall structure of LM. In this work, we investigated computationally and experimentally the mechanical performance of a novel everolimus-eluting stent (SYNERGY MEGATRON) purpose-built for interventions to large proximal coronary segments, including LM. MEGATRON stent has been purposefully designed to sustain its structural integrity at higher expansion diameters and to provide optimal lumen coverage. Four patient-specific LM geometries were 3D reconstructed and stented computationally with finite element analysis in a well-validated computational stent simulation platform under different homogeneous and heterogeneous plaque conditions. Four different everolimus-eluting stent designs (9-peak prototype MEGATRON, 10-peak prototype MEGATRON, 12-peak MEGATRON, and SYNERGY) were deployed computationally in all bifurcation geometries at three different diameters (i.e., 3.5, 4.5, and 5.0 mm). The stent designs were also expanded experimentally from 3.5 to 5.0 mm (blind analysis). Stent morphometric and biomechanical indices were calculated in the computational and experimental studies. In the computational studies the 12-peak MEGATRON exhibited significantly greater expansion, better scaffolding, smaller vessel prolapse, and greater radial strength (expressed as normalized hoop force) than the 9-peak MEGATRON, 10-peak MEGATRON, or SYNERGY (p < 0.05). Larger stent expansion diameters had significantly better radial strength and worse scaffolding than smaller stent diameters (p < 0.001). Computational stenting showed comparable scaffolding and radial strength with experimental stenting. 12-peak MEGATRON exhibited better mechanical performance than the 9-peak MEGATRON, 10-peak MEGATRON, or SYNERGY. Patient-specific computational LM stenting simulations can accurately reproduce experimental stent testing, providing an attractive framework for cost- and time-effective stent research and development.

Current Design Rules for Welding of Wind Energy Structures for Arctic Conditions

2019 ◽  
Vol 822 ◽  
pp. 452-458
Author(s):  
Sergey Lopaev ◽  
Pavel Layus ◽  
Paul Kah ◽  
Sergey Parshin
Keyword(s):  
Wind Energy ◽  
Structural Integrity ◽  
Structural Characteristics ◽  
Welding Process ◽  
Climatic Conditions ◽  
Welding Parameters ◽  
Reliable Operation ◽  
Arctic Conditions ◽  
Current Design ◽  
Standards And Guidelines

An article presents a review of current standards and guidelines in the field welding fabrication requirements for wind energy structures in arctic conditions. Extreme climatic conditions, such as Arctic, have a strong influence on the requirements for wind turbines structural characteristics, materials and fabrication methods. Special attention has to be paid for selecting steels with suitable mechanical properties, processing methods and delivery conditions. Additionally, it is highly important to select proper welding process and welding parameters, so that the structural integrity and reliable operation can be achieved.

scholarly journals Preparation and properties of hybrid materials for high-rise constructions

2018 ◽  
Vol 33 ◽  
pp. 02075 ◽  
Author(s):  
Tatyana Matseevich
Keyword(s):  
Stress Relaxation ◽  
Epoxy Resin ◽  
Relaxation Process ◽  
Hybrid Materials ◽  
Mechanical Performance ◽  
Mechanical Relaxation ◽  
Physical Parameters ◽  
Quasi Equilibrium ◽  
High Rise ◽  
Long Time

The theme of the research is important because it allows to use hybrid materials as finishing in the high-rise constructions. The aim of the study was the development of producing coloured hybrid materials based on liquid glass, a polyisocyanate, epoxy resin and 2.4-toluylenediisocyanate. The detailed study of the process of stress relaxation at different temperatures in the range of 20-100°C was provided. The study found that the obtained materials are subject to the simplified technology. The materials easy to turn different colors, and dyes (e.g. Sudan blue G) are the catalysts for the curing process of the polymeric precursors. The materials have improved mechanical relaxation properties, possess different color and presentable, can be easily combined with inorganic base (concrete, metal). The limit of compressive strength varies from 32 to 17.5 MPa at a temperature of 20 to 100°C. The values σ∞ are from 20.4 to 7.7 MPa within the temperature range from 20 to 100°C. The physical parameters of materials were evaluated basing on the data of stress relaxation: the initial stress σ0, which occurs at the end of the deformation to a predetermined value; quasi-equilibrium stress σ∞, which persists for a long time relaxation process. Obtained master curves provide prediction relaxation behavior for large durations of relaxation. The study obtained new results. So, the addition of epoxy resin in the composition of the precursor improves the properties of hybrid materials. By the method of IR spectroscopy identified chemical transformations in the course of obtaining the hybrid material. Evaluated mechanical performance of these materials is long-time. Applied modern physically-based memory functions, which perfectly describe the stress relaxation process.

scholarly journals Mechanical Strength Study of a Cranial Implant Using Computational Tools

2022 ◽  
Vol 12 (2) ◽  
pp. 878
Author(s):  
Pedro O. Santos ◽  
Gustavo P. Carmo ◽  
Ricardo J. Alves de Sousa ◽  
Fábio A. O. Fernandes ◽  
Mariusz Ptak
Keyword(s):  
Structural Integrity ◽  
Mechanical Performance ◽  
Skull Fracture ◽  
Human Head ◽  
Element Model ◽  
Von Mises Stress ◽  
Cranial Implant ◽  
Von Mises ◽  
Two Parameters ◽  
The Brain

The human head is sometimes subjected to impact loads that lead to skull fracture or other injuries that require the removal of part of the skull, which is called craniectomy. Consequently, the removed portion is replaced using autologous bone or alloplastic material. The aim of this work is to develop a cranial implant to fulfil a defect created on the skull and then study its mechanical performance by integrating it on a human head finite element model. The material chosen for the implant was PEEK, a thermoplastic polymer that has been recently used in cranioplasty. A6 numerical model head coupled with an implant was subjected to analysis to evaluate two parameters: the number of fixation screws that enhance the performance and ensure the structural integrity of the implant, and the implant’s capacity to protect the brain compared to the integral skull. The main findings point to the fact that, among all tested configurations of screws, the model with eight screws presents better performance when considering the von Mises stress field and the displacement field on the interface between the implant and the skull. Additionally, under the specific analyzed conditions, it is observable that the model with the implant offers more efficient brain protection when compared with the model with the integral skull.

Chopinian Particularities in Piano’s Sonata op. 58

2021 ◽  
Vol 13 (62) (SI) ◽  
pp. 69-78
Author(s):  
Lioara FRĂȚILĂ
Keyword(s):  
Structural Integrity ◽  
Classical Type ◽  
Late Period ◽  
Structural Elements ◽  
Piano Sonata ◽  
Strong Connection ◽  
Sonata Cycle ◽  
Aesthetic Results ◽  
The Postponement

The paper herein highlights those aspects of Chopin’s Piano Sonata Op.58 that demonstrate the strong connection with the classical-type sonata, its significance and the evolution of expression. Chopin’s Third Piano Sonata, Op.58 is the largest solo work of his late period. Chopin’s successful combination of the Classical and the Romantic aesthetic, results in an effective balancing of structural integrity and emotional fulfilment. Every moment of Op.58 possesses qualities of movements in a traditional sonata cycle; however, the tendency to blend structural elements, the expansion of thematic material and the postponement of climaxes contribute to Chopin’s distinctive treatment of the sonata genre style include blurring of genres, complex use of chromaticism, intricacy of counterpoint, textural and thematic variety

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