scholarly journals Durability Assessment of Composite Structural Element Reinforced with Fabric due to Delamination

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Jerzy Marszałek ◽  
Jacek Stadnicki
Keyword(s):  
Computational Model ◽  
Carbon Fibers ◽  
Construction Materials ◽  
Calculation Model ◽  
Structural Element ◽  
Plain Weave ◽  
Construction Element ◽  
Experimental Stand ◽  
Durability Assessment ◽  
Multi Phase

AbstractLayer composites reinforced with fabrics – laminates are construction materials in which mechanical properties can be shaped by designing their microstructure appropriately. However, the multi-phase microstructure of laminates makes it difficult to calculate the strength of the laminate constructions, especially when the reinforcement is a fabric. The article presents a special calculation model for determining the strength of an exemplary construction element made of laminate reinforced with a roving fabric with a plain weave made of carbon fibers. The computational model reflected in a simplified way the laminate microstructure, i.e. the number and orientation of the reinforcement fabric layers and its weave, and enabled a simulation of the behavior of the construction element under load up to fracture, which occurred as a result of breaking the reinforcement and interlayer crack – delamination. The simulation results were compared with the results of experimental stand tests. A method of modifying the computational model for laminates reinforced with non-plain weave was also suggested.

scholarly journals Selection of Novel Geopolymeric Mortars for Sustainable Construction Applications Using Fuzzy Topsis Approach

2020 ◽  
Vol 12 (15) ◽  
pp. 5987 ◽  
Author(s):  
Manfredi Saeli ◽  
Rosa Micale ◽  
Maria Paula Seabra ◽  
João A. Labrincha ◽  
Giada La Scalia
Keyword(s):  
Fly Ash ◽  
Construction Materials ◽  
Fuzzy Topsis ◽  
Industrial Wastes ◽  
Engineering Properties ◽  
Structural Element ◽  
Structural Applications ◽  
Multi Criteria Analysis ◽  
Biomass Fly Ash ◽  
Topsis Approach

Construction is recognized as one of the most polluting and energy consuming industries worldwide, especially in developing countries. Therefore, Research and Development (R&D) of novel manufacturing technologies and green construction materials is becoming extremely compelling. This study aims at evaluating the reuse of various wastes, originated in the Kraft pulp-paper industry, as raw materials in the manufacture of novel geopolymeric (GP) mortars whose properties fundamentally depend on the target application (e.g., insulating panel, partition wall, structural element, furnishing, etc.). Five different wastes were reused as filler: Two typologies of Biomass Fly Ash, calcareous sludge, grits, and dregs. The produced samples were characterized and a multi criteria analysis, able to take into account not only the engineering properties, but also the environmental and economic aspects, has been implemented. The criteria weights were evaluated using the Delphi methodology. The fuzzy Topsis approach has been used to consider the intrinsic uncertainty related to unconventional materials, as the produced GP-mortars. The computational analysis showed that adding the considered industrial wastes as filler is strongly recommended to improve the performance of materials intended for structural applications in construction. The results revealed that the formulations containing 5 wt.% of calcareous sludge, grits, and dregs and the one containing 7.5 wt.% of calcareous sludge, grits, dregs, and Biomass Fly Ash-1 have emerged as the best alternatives. Furthermore, it resulted that the Biomass Fly Ash-2 negatively influences the structural performance and relative rank of the material. Finally, this case study clearly shows that the fuzzy Topsis multi-criteria analysis represents a valuable and easy tool to investigate construction materials (either traditional and unconventional) when an intrinsic uncertainty is related to the measurement of the quantitative and qualitative characteristics.

scholarly journals DISPLACEMENT MONITORING AND SENSITIVITY ANALYSIS IN THE OBSERVATIONAL METHOD

2013 ◽  
Vol 35 (3) ◽  
pp. 25-43 ◽  
Author(s):  
Karolina Górska ◽  
Zbigniew Muszyński ◽  
Jarosław Rybak
Keyword(s):  
Sensitivity Analysis ◽  
Computational Model ◽  
Cohesive Soil ◽  
Calculation Model ◽  
Observational Method ◽  
Deep Excavation ◽  
Sheet Pile ◽  
Displacement Monitoring ◽  
Excavation Support ◽  
Construction Works

Abstract This work discusses the fundamentals of designing deep excavation support by means of observational method. The effective tools for optimum designing with the use of the observational method are both inclinometric and geodetic monitoring, which provide data for the systematically updated calibration of the numerical computational model. The analysis included methods for selecting data for the design (by choosing the basic random variables), as well as methods for an on-going verification of the results of numeric calculations (e.g., MES) by way of measuring the structure displacement using geodetic and inclinometric techniques. The presented example shows the sensitivity analysis of the calculation model for a cantilever wall in non-cohesive soil; that analysis makes it possible to select the data to be later subject to calibration. The paper presents the results of measurements of a sheet pile wall displacement, carried out by means of inclinometric method and, simultaneously, two geodetic methods, successively with the deepening of the excavation. This work includes also critical comments regarding the usefulness of the obtained data, as well as practical aspects of taking measurement in the conditions of on-going construction works.

scholarly journals Valorization of Lignin as a Sustainable Component of Structural Materials and Composites: Advances from 2011 to 2019

2020 ◽  
Vol 12 (2) ◽  
pp. 734 ◽  
Author(s):  
Menisha S. Karunarathna ◽  
Rhett C. Smith
Keyword(s):  
Chemical Modification ◽  
Functional Groups ◽  
Carbon Fibers ◽  
Network Structure ◽  
Phenol Formaldehyde ◽  
Construction Materials ◽  
Structural Elements ◽  
Automotive Components ◽  
Future Developments ◽  
Technical Issues

Lignin is the most abundant aromatic biopolymer and is the sustainable feedstock most likely to supplant petroleum-derived aromatics and downstream products. Rich in functional groups, lignin is largely peerless in its potential for chemical modification towards attaining target properties. Lignin’s crosslinked network structure can be exploited in composites to endow them with remarkable strength, as exemplified in timber and other structural elements of plants. Yet lignin may also be depolymerized, modified, or blended with other polymers. This review focuses on substituting petrochemicals with lignin derivatives, with a particular focus on applications more significant in terms of potential commercialization volume, including polyurethane, phenol-formaldehyde resins, lignin-based carbon fibers, and emergent melt-processable waste-derived materials. This review will illuminate advances from the last eight years in the prospective utilization of such lignin-derived products in a range of application such as adhesives, plastics, automotive components, construction materials, and composites. Particular technical issues associated with lignin processing and emerging alternatives for future developments are discussed.

Experimental Verification of the Properties of Fibres for the Mechanisms Based on Parallel Kinematic Structures

2013 ◽  
Vol 486 ◽  
pp. 195-200
Author(s):  
Jaroslav Václavík ◽  
Pavel Polach
Keyword(s):  
Computational Model ◽  
Experimental Verification ◽  
Mechanical Systems ◽  
Inclined Plane ◽  
Fibre Properties ◽  
Plane Vibration ◽  
Experimental Stand ◽  
Axial Forces ◽  
Parallel Kinematic

The paper was written in the framework of research in mechanisms of the increased mobility on the basis of parallel kinematic structures, for which a fibre control instead of rigid elements is designed. The experiment is focused on the verification of the fibre properties in simplified mechanical systems such as motion on an inclined plane, vibration of a moving weight hanging on a fibre and fibre interaction with two types of pulley. The arrangement and instrumentation of the experimental stand and of the system for the measurement of position and axial forces in a fibre are described. The results should serve for tuning the computational model, the results of which are also presented in the framework of specific experiments.

scholarly journals Shear Behavior of Fiber Reinforced Concrete Beams with Basalt FRP Reinforcing Bars and Glass FRP Stirrups

2020 ◽  
Author(s):  
Abathar AL-Hamrani ◽  
Wael Alnahhal
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fibers ◽  
Glass Fibers ◽  
Construction Materials ◽  
Steel Reinforcement ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced ◽  
Reinforcing Bars ◽  
Frp Bars

The State of Qatar suffers from a harsh environment in the form of high temperature that prevails almost all year round in addition to severe humidity and coastal conditions. This exposure leads to the rapid deterioration and the reduction of the life span of reinforced concrete (RC) infrastructure. The full functionality and safe use of the infrastructure in such environments can only be maintained by holistic approaches including the use of advanced materials for new construction.With the developments in materials science, the advanced composites, especially fiber reinforced polymer (FRP) materials are becoming viable alternatives to the traditional construction materials. Having superior durability against corrosion, versatility for easy in-situ applications and enhanced weight-to-strength ratios compared to their counterpart conventional materials, FRPs are promising to be the future of construction materials. More recently, FRP composites made of basalt FRP (BFRP) have been introduced as an alternative to traditional steel reinforcement at a price comparable to glass fibers of about $2.5–5.0 per kg, which is significantly lower than carbon fibers. BFRP bars are characterized by their corrosion resistance, greater strain at failure than carbon fibers, and better chemical resistant than glass fibers, particularly in a strongly alkaline environment. Knowing that FRP bars are anisotropic materials with weaker strength in the transverse direction compared with the longitudinal direction, and having a relatively low modulus of elasticity compared with steel reinforcement, it is important to investigate the concrete contribution to shear strength for beams reinforced with BFRP bars. In addition, due to the elastic performance of the FRP reinforcing bars compared with steel bars, FRP bars fail in a brittle manner. Moreover, concrete itself is a brittle material. Previous investigations have shown that using discrete fibers in concrete increases its ductility due to the large compressive strains exhibited at failure. Therefore, basalt macro-fibers is proposed in this study. A total of 14 concrete beam specimens were tested under four point loading until failure. The parameters investigated included the reinforcement ratio (2rb, 3.1rb, and 4.53rb, where rb is the balanced reinforcement ratio), the span to depth ratio (a/d=2.5, and a/d=3.3), the spacing between stirrups (S1=170mm, and S2=250mm) and the basalt fiber volume fraction (0%, 0.75% and 1.5%). Test results clearly showed that both BFRP bars and basalt macro-fibers can be used as sustainable and eco-friendly alternative materials in Concrete Structures in Qatar.

scholarly journals Validation of the mean systemic filling pressure assessment with preserved arterial blood flow by comparing two methods of calculation 

2021 ◽  
Author(s):  
Roberto Alberto De Blasi ◽  
Stefano Finazzi
Keyword(s):  
Near Infrared ◽  
Venous Occlusion ◽  
Calculation Model ◽  
Arterial Blood Flow ◽  
Venous Compliance ◽  
Model Method ◽  
Arterial Blood ◽  
Methods Of Calculation ◽  
Multi Phase

Abstract Significance: We developed a method for measuring in vivo venular volumes and pressures in the limbs using near-infrared spectroscopy (NIRS).Aim: 36 We aimed to validate the NIRS methodology by comparing two independent methods of calculation based on different physiological approaches.Approach: Pressure-volumes curves were recorded following graded venous occlusion on the forearm. Values from a multi-phase model (method 1) were compared with data derived from a resistor-capacitance calculation model (method 2) based on arterial pressure and venous compliance. We tested these methods on 10 healthy participants at rest and during exercise and on 6 severely ill patients.Results: Pressure-volume curves measured by method 1 were comparable with those calculated by method 2. Venular volumes calculated using method 1 correlated linearly with those calculated using method 2 both in participants (R2 = 0.98, p < 0.001) and in patients (R2 = 0.94, p < 0.001). The Bland-Altman test showed a good agreement between methods with few values out of the range of ± 1.96 SD.Conclusions: Our findings showed that the NIRS methodology may be valid for the assessment of venular bed with no flow interruption. Further research will be required to confirm the relevance of methodology in the clinical setting.

scholarly journals MACLOCYCLE FATIGUE OF STRUCTURAL ELEMENT UNDER SOFT LOADING.

2021 ◽  
Vol 7 (3(84)) ◽  
pp. 4-7
Author(s):  
A. Penkin ◽  
К. Savinova
Keyword(s):  
Plastic Deformation ◽  
Structural Element ◽  
Method Of Calculation ◽  
Construction Element ◽  
Soft Loading ◽  
Deformation Diagrams

In the article the method of calculation of capacity for work construction element of low – cycle deformation diagrams with considering of cyclic instability and unilateral accommodation of plastic deformation.

scholarly journals Fatigue Prediction of Aluminum Alloys Considering Critical Plane Orientation under Complex Stress States

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3877
Author(s):  
Marta Kurek
Keyword(s):  
Fatigue Life ◽  
Experimental Studies ◽  
Construction Materials ◽  
Estimation Algorithm ◽  
Complex Stress ◽  
Calculation Model ◽  
Graphical Form ◽  
Critical Plane ◽  
Plane Orientation ◽  
Stress States

This publication is intended to present a new way of estimating the fatigue life of various construction materials. Carpinteri’s proposal was modified by replacing the fatigue limits ratio with the value of the normal to shear stress ratio for a given number of cycles. In this study, the proposed criterion and calculation model was verified for the selected group of aluminium alloys. The purpose of the analysis of the experimental studies was to check the effectiveness of the proposed method of estimating fatigue life under the applied bending and torsional load conditions. The results of the fatigue calculations are presented in graphical form by means of diagrams showing the comparison of design and experimental strength. Before fatigue life was calculated, the critical plane orientation according to Carpinteri’s model and the proposed model were determined. After analyzing the results of the comparison of design and experimental durability, it can be stated that the proposed fatigue life estimation algorithm gives satisfactory results for multiaxial cyclic loads.

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