Search results
1 – 10 of 696Chiara Bedon and Christian Louter
Glass material is largely used for load-bearing components in buildings. For this reason, standardized calculation methods can be used in support of safe structural design in…
Abstract
Purpose
Glass material is largely used for load-bearing components in buildings. For this reason, standardized calculation methods can be used in support of safe structural design in common loading and boundary conditions. Differing from earlier literature efforts, the present study elaborates on the load-bearing capacity, failure time and fire endurance of ordinary glass elements under fire exposure and sustained mechanical loads, with evidence of major trends in terms of loading condition and cross-sectional layout. Traditional verification approaches for glass in cold conditions (i.e. stress peak check) and fire endurance of load-bearing members (i.e. deflection and deflection rate limits) are assessed based on parametric numerical simulations.
Design/methodology/approach
The mechanical performance of structural glass elements in fire still represents an open challenge for design and vulnerability assessment. Often, special fire-resisting glass solutions are used for limited practical applications only, and ordinary soda-lime silica glass prevails in design applications for load-bearing members. Moreover, conventional recommendations and testing protocols in use for load-bearing members composed of traditional constructional materials are not already addressed for glass members. This paper elaborates on the fire endurance and failure detection methods for structural glass beams that are subjected to standard ISO time–temperature for fire exposure and in-plane bending mechanical loads. Fire endurance assessment methods are discussed with the support of Finite Element (FE) numerical analyses.
Findings
Based on extended parametric FE analyses, multiple loading, geometrical and thermo-mechanical configurations are taken into account for the analysis of simple glass elements under in-plane bending setup and fire exposure. The comparative results show that – in most of cases – thermal effects due to fire exposure have major effects on the actual load-bearing capacity of these members. Moreover, the conventional stress peak verification approach needs specific elaborations, compared to traditional calculations carried out in cold conditions.
Originality/value
The presented numerical results confirm that the fire endurance analysis of ordinary structural glass elements is a rather complex issue, due to combination of multiple aspects and influencing parameters. Besides, FE simulations can provide useful support for a local and global analysis of major degradation and damage phenomena, and thus support the definition of simple and realistic verification procedures for fire exposed glass members.
Details
Keywords
Royal Madan and Shubhankar Bhowmick
The purpose of this study is to investigate Thermo-mechanical limit elastic speed analysis of functionally graded (FG) rotating disks with the temperature-dependent material…
Abstract
Purpose
The purpose of this study is to investigate Thermo-mechanical limit elastic speed analysis of functionally graded (FG) rotating disks with the temperature-dependent material properties. Three different material models i.e. power law, sigmoid law and exponential law, along with varying disk profiles, namely, uniform thickness, tapered and exponential disk was considered.
Design/methodology/approach
The methodology adopted was variational principle wherein the solution was obtained by Galerkin’s error minimization principle. The Young’s modulus, coefficient of thermal expansion and yield stress variation were considered temperature-dependent.
Findings
The study shows a substantial increase in limit speed as disk profiles change from uniform thickness to exponentially varying thickness. At any radius in a disk, the difference in von Mises stress and yield strength shows the remaining stress-bearing capacity of material at that location.
Practical implications
Rotating disks are irreplaceable components in machinery and are used widely from power transmission assemblies (for example, gas turbine disks in an aircraft) to energy storage devices. During operations, these structures are mainly subjected to a combination of mechanical and thermal loadings.
Originality/value
The findings of the present study illustrate the best material models and their grading index, desired for the fabrication of uniform, as well as varying FG disks. Finite element analysis has been performed to validate the present study and good agreement between both the methods is seen.
Details
Keywords
The purpose of this paper is to evaluate hygro-thermo-mechanically induced normalized stress intensity factor (NSIF) of an edge crack symmetric angle-ply piezo laminated composite…
Abstract
Purpose
The purpose of this paper is to evaluate hygro-thermo-mechanically induced normalized stress intensity factor (NSIF) of an edge crack symmetric angle-ply piezo laminated composite plate (PLCP) using displacement correlation method.
Design/methodology/approach
In the present work, the governing equations are solved through conventional finite element method combined with higher order shear deformation plate theory utilizing the micromechanical approach.
Findings
The effects of crack length, the thickness of the plate and piezoelectric layer, stacking sequences, fiber volume fraction, position of piezoelectric layer, change in moisture and temperature, and voltage on the NSIF are examined. The numerical results are presented in the form of a table for the better understanding and accuracy. The present outlined approach is validated with results available in the literature. These results can become a benchmark for future studies.
Research limitations/implications
The mathematical models theoretically have been developed by considering different parameters. The results are generated using MATLAB 2015 software developed by the authors’ side.
Originality/value
The fracture analysis of a single edge crack PLCP with the effect of a piezoelectric layer at the different location of cracked structures, plate thickness, and actuator voltage and hygro-thermo loading is the novelty of research for health monitoring and high-performance analysis.
Details
Keywords
Youssouf Belabed, Bachir Kerboua and Mostapha Tarfaoui
The sustainability of the structures is not only a technical goal, but also a matter of social and environmental values. This requires the researchers to use very rigid, highly…
Abstract
Purpose
The sustainability of the structures is not only a technical goal, but also a matter of social and environmental values. This requires the researchers to use very rigid, highly durable and corrosion-resistant composite structures in order to achieve the technical, environmental and social goals. The purpose of this paper is to present an original work on reducing the interfacial stresses of bonded structures with fibre-reinforced polymers (FRP) plates based on new taper design.
Design/methodology/approach
In this proposed concept, the effect of combined taper is investigated on reducing interfacial stresses, attempting to enhance the structure performance and address the debonding problem that comes with reinforcing techniques. This research is carried out by using finite element analysis, incorporating many new parameters.
Findings
As a result, a new solution is discovered that combined taper in both adhesive layer and composite laminate, which significantly reduces the interfacial stresses at the end of the FRP plate. Additionally, a parametric study is carried out in order to determine the optimal configurations of taper dimensions as well as other parameters that influence the stress concentration distribution at the edge of the adherends.
Practical implications
This new design regarding the reduction of interfacial stresses will help in increasing the lifespan of damaged structures reinforced by FRP composites, preserving thus its technical, historical and social values.
Originality/value
The paper uses straight, concave and convex fillets with inverse taper as a new design solution with new parameters including thermo-mechanical loads and pre-stressed FRP plate with multi-layer, fibre orientation and shear-lag effects.
Details
Keywords
Haijie Wang, Xintian Liu, Que Wu, Xiaolan Wang and Yansong Wang
The purpose of this paper is to obtain a more accurate fatigue life of structures by introducing the surface roughness into fatigue life prediction model.
Abstract
Purpose
The purpose of this paper is to obtain a more accurate fatigue life of structures by introducing the surface roughness into fatigue life prediction model.
Design/methodology/approach
Based on the fatigue life prediction model with surface roughness correction, the shock absorber cylinder is taken as an example to verify the feasibility of the improved method. Based on the load of the shock absorber cylinder during driving, fatigue experiments are performed under longitudinal and lateral forces, respectively. Then, the fatigue life predicted by the modified model is compared with that predicted by the traditional model.
Findings
By comparing with the test results, considering the influence of mean stress, the Manson method is more accurate in life prediction. Then, the modified Manson-Coffin and Manson method with surface roughness is more accurate in life prediction under longitudinal force and lateral forces, respectively. This verifies the feasibility of the improved method with the surface roughness.
Originality/value
The research on the influence of surface roughness on fatigue life can lay the technical foundation for the life prediction of products and have great significance to the quality evaluation of products.
Details
Keywords
Ranjit Kumar Chaudhary, Tathagata Roy and Vasant Matsagar
Despite recognizing the significance of risk-based frameworks in fire safety engineering, the usual approach in structural fire design is largely member/component level, wherein…
Abstract
Purpose
Despite recognizing the significance of risk-based frameworks in fire safety engineering, the usual approach in structural fire design is largely member/component level, wherein effect of uncertainties influencing the fire resistance of structures are not explicitly considered. In this context, a probabilistic framework is presented to investigate the vulnerability of a reinforced concrete (RC) members and structure under fire loading scenario.
Design/methodology/approach
The RC structures exposed to fire are modeled in a finite element (FE) platform incorporating material and geometric nonlinearity, in which the transient thermo-mechanical analysis is carried out by suitably incorporating the temperature variation of thermal and mechanical properties of both concrete and steel rebar. The stochasticity in the system is considered in structural resistance, thermal and fire model parameters, and the subsequent fragility curves are developed considering threshold limit state of deflection.
Findings
The fire resistance of RC structure is reported to be significantly lower in comparison to the RC members, thereby illustrating the current prescriptive design approaches based on studies of structural member behavior to be crucial from a safety and reliability point of view.
Practical implications
The framework developed for the vulnerability assessment of RC structures under fire hazard through FE analysis can be effectively used to estimate the structural fire resistance for other similar structure to enhance safety and reliability of structures under such extreme threats.
Originality/value
The paper proposes a novel methodology for vulnerability assessment of three-dimensional RC structures under fire hazard through FE analysis and provides comparison of the structural fragility with fragility developed for structural members. Moreover, the research emphasizes to assume 3D behavior of the structure rather than the approximate 2D behavior.
Details
Keywords
Royal Madan, Shubhankar Bhowmick, Lazreg Hadji and Ali Alnujaie
In this work, the effect of porosity volume fraction, porosity types, material grading index, variable disk profiles and aspect ratio on disk performance was studied by performing…
Abstract
Purpose
In this work, the effect of porosity volume fraction, porosity types, material grading index, variable disk profiles and aspect ratio on disk performance was studied by performing limit elastic speed analysis of functionally graded porous rotating disks (PFGM) under thermo-mechanical loading.
Design/methodology/approach
The composition change was varied by employing the power law function. The thermo-mechanical properties of PFGM such as Young's modulus and yield strength were estimated using modified rule of mixture, for density and coefficient of thermal expansion rule of mixture was used. The even and uneven distribution of porosity in a disk was taken as uniform, symmetrical, inner maximum and outer maximum. The problem was then solved with the help of the variational principle and Galerkin's error minimization theory.
Findings
The research reveals that the grading parameter, disk geometry and porosity distribution have a significant impact on the limit elastic speed in comparison to the aspect ratio.
Practical implications
The study determines a range of operable speeds for porous and non-porous disk profiles that the industry can utilize to estimate structural performance.
Originality/value
A finite element investigation was conducted to validate the findings of the present study. Limit elastic analysis of porous FG disks under thermo-mechanical loading has not been studied before.
Details
Keywords
Ritesh Kumar, Himanshu Pathak, Akhilendra Singh and Mayank Tiwari
The purpose of this paper is to analyze the repair of a straight and angular crack in the structure using a piezoelectric material under thermo-mechanical loading by the extended…
Abstract
Purpose
The purpose of this paper is to analyze the repair of a straight and angular crack in the structure using a piezoelectric material under thermo-mechanical loading by the extended finite element method (XFEM) approach. This provides a general and simple solution for the modeling of crack in the structure to analyze the repair.
Design/methodology/approach
The extended finite element method is used to model crack geometry. The crack surface is modeled by Heaviside enrichment function while the crack front is modeled by branch enrichment functions.
Findings
The effectiveness of the repair is measured in terms of stress intensity factor and J-integral. The critical voltage at which patch repair is most effective is evaluated and presented. Optimal patch shape, location of patch, adhesive thickness and adhesive modulus are obtained for effective repair under thermo-mechanical loading environment.
Originality/value
The presented numerical modeling and simulation by the XFEM approach are of great benefit to analyze crack repair in two-dimensional and three-dimensional structures using piezoelectric patch material under thermo-mechanical loading.
Details
Keywords
The purpose of this paper was to study the combined effect of hygro and thermo-mechanical behavior on a plastic encapsulated micro-electro-mechanical systems (MEMS) package during…
Abstract
Purpose
The purpose of this paper was to study the combined effect of hygro and thermo-mechanical behavior on a plastic encapsulated micro-electro-mechanical systems (MEMS) package during the reflow process after exposed to a humid environment for a prolonged time. Plastic encapsulated electronic packages absorb moisture when they are subjected to humid ambient conditions.
Design/methodology/approach
Thus, a comprehensive stress model is established for a three-axis accelerometer MEMS package, with detailed considerations of fundamentals of mechanics such as heat transfer, moisture diffusion and hygro-thermo-mechanical stress. In this study, the mold compound is considered to be the most critical plastic material in MEMS package. Other plastic components of thin film materials can be disregarded due to their small sizes such as die attach and Bismaleimide Triazine (BT) core, even though they are also susceptible to moisture. Thus, only the moisture-induced properties of mold compound were obtained from the proposed experiments. From the desorption measurement after preconditioning at 85°C/85 per cent relative humidity (RH), the saturated moisture content and diffusivity were obtained by curve fitting the data to Fick’s equation. In addition, a new experimental setup was devised using the digital image correlation system together with a precision weight scale to obtain the coefficient of hygroscopic swelling (CHS) at different temperatures.
Findings
The experimental results show that the diffusion coefficient of mold compound material follows Arrhenius equation well. Also, it is shown that the CHS of mold compound increases as temperature increases. Experimentally obtained moisture properties were then used to analyze the combined behavior (thermo-hygro-mechanical) of fully saturated MEMS package during the reflow process using a finite element analysis (FEA) with the classical analogy method. Finally, the warpage and stresses inside the MEMS package were analyzed to compare the effects of hygroscopic, thermal and hygro-thermo-mechancal behaviors.
Originality/value
In this study, unlike the other researches, the moisture effects are investigated specifically for MEMS package which is relatively smaller in scale than conventional electronic packages. Also, as a conjugated situation, MEMS package experiences both humid and temperature during the moisture resistance test. Thus, major objective of this study is to verify stress state inside MEMS package during the reflow process which follows the preconditioning at 85°C/85 per cent RH. To quantify the stresses in the package, accurate information of material properties is experimentally obtained and used to improve modeling accuracy.
Details
Keywords
Dhafer Abdul Ameer Shnawah, Mohd Faizul Bin Mohd Sabri, Irfan Anjum Badruddin and Suhana Said
The purpose of this paper is to discuss the reliability of board level Sn‐Ag‐Cu (SAC) solder joints in terms of both thermal cycling and drop impact loading conditions, and…
Abstract
Purpose
The purpose of this paper is to discuss the reliability of board level Sn‐Ag‐Cu (SAC) solder joints in terms of both thermal cycling and drop impact loading conditions, and further modification of the characteristics of low Ag‐content SAC solder joints using minor alloying elements to withstand both thermal cycle and drop impact loads.
Design/methodology/approach
The thermal cycling and drop impact reliability of different Ag‐content SAC bulk solder will be discussed from the viewpoints of mechanical and micro‐structural properties.
Findings
The best SAC composition for drop performance is not necessarily the best composition for optimum thermal cycling reliability. The content level of silver in SAC solder alloys can be an advantage or a disadvantage depending on the application, package and reliability requirements. The low Ag‐content SAC alloys with different minor alloying elements such as Mn, Ce, Bi, Ni and Ti display good performance in terms of both thermal cycling and drop impact loading conditions.
Originality/value
The paper details the mechanical and micro‐structural properties requirements to design a robust bulk SAC solder joint. These properties provide design and manufacturing engineers with the necessary information when deciding on a solder alloy for their specific application.
Details