Averaged strain energy density to assess mixed mode I/III fracture of U-notched GPPS samples

Saboori, Behnam,Torabi, A.R.,Berto, F.,Razavi, S.M.J. Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.6

In the present contribution, fracture resistance of U-notched GPPS members under mixed mode I/III loading conditions is assessed by using the Averaged Strain Energy Density (ASED) criterion. This criterion has been founded based on the ASED parameter averaged over a well-defined control volume embracing the notch edge. The validation of the theoretical criterion predictions is evaluated through comparing with the results of a series of mixed mode I/III fracture tests conducted on rectangular-shaped GPPS specimens weakened by a single edge U-notch. A recently developed apparatus for mixed mode I/III fracture experiments is employed for measuring the fracture loads of the specimens. The test samples are fabricated with different notch tip radii with the aim of evaluating the influence of this major feature of the U-notched components on the mixed mode I/III fracture behavior. It is shown that the onset of brittle fracture in U-notched GPPS specimens under various combinations of tension and out-of-plane shear can well be predicted by means of the ASED criterion.

Free vibration analysis of tapered FRP transmission poles with flexible joint by finite element method

Saboori, Behnam,Khalili, Seyed Mohammad Reza Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.42 No.3

Since relatively low elasticity modulus of the FRP materials results in lower natural frequencies, it is necessary to study the free vibration of FRP transmission poles. In this paper, the free vibration of tapered FRP transmission poles with thin-walled circular cross-section is investigated by a tapered beam element. To model the flexible joints of the modular poles, a rotational spring model is used. Modal analysis is performed for typical FRP poles with/without joint and they are also modeled by ANSYS commercial finite element software. There is a good correlation between the results of the tapered beam finite element model and those obtained from ANSYS as well as the existing experimental results. The effects of different geometries, material lay-ups, concentrated masses at the pole tip, and joint flexibilities are evaluated. Moreover, it is concluded that using tougher fibres at the inner and outer layers of the cross-section, results in higher natural frequencies, significantly.

On the properties of brain sub arachnoid space and biomechanics of head impacts leading to traumatic brain injury

Saboori, Parisa,Sadegh, Ali Techno-Press 2014 Advances in biomechanics & applications Vol.1 No.4

The human head is identified as the body region most frequently involved in life-threatening injuries. Extensive research based on experimental, analytical and numerical methods has sought to quantify the response of the human head to blunt impact in an attempt to explain the likely injury process. Blunt head impact arising from vehicular collisions, sporting injuries, and falls leads to relative motion between the brain and skull and an increase in contact and shear stresses in the meningeal region, thereby leading to traumatic brain injuries. In this paper the properties and material modeling of the subarachnoid space (SAS) as it relates to Traumatic Brain Injuries (TBI) is investigated. This was accomplished using a simplified local model and a validated 3D finite element model. First the material modeling of the trabeculae in the Subarachnoid Space (SAS) was investigated and validated, then the validated material property was used in a 3D head model. In addition, the strain in the brain due to an impact was investigated. From this work it was determined that the material property of the SAS is approximately E = 1150 Pa and that the strain in the brain, and thus the severity of TBI, is proportional to the applied impact velocity and is approximately a quadratic function. This study reveals that the choice of material behavior and properties of the SAS are significant factors in determining the strain in the brain and therefore the understanding of different types of head/brain injuries.

Free vibration analysis of tapered FRP transmission poles with flexible joint by finite element method

Behnam Saboori,Seyed Mohammad Reza Khalili 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.42 No.3

Since relatively low elasticity modulus of the FRP materials results in lower natural frequencies, it is necessary to study the free vibration of FRP transmission poles. In this paper, the free vibration of tapered FRP transmission poles with thin-walled circular cross-section is investigated by a tapered beam element. To model the flexible joints of the modular poles, a rotational spring model is used. Modal analysis is performed for typical FRP poles with/without joint and they are also modeled by ANSYS commercial finite element software. There is a good correlation between the results of the tapered beam finite element model and those obtained from ANSYS as well as the existing experimental results. The effects of different geometries, material lay-ups, concentrated masses at the pole tip, and joint flexibilities are evaluated. Moreover, it is concluded that using tougher fibres at the inner and outer layers of the cross-section, results in higher natural frequencies, significantly.

Transient response analysis of tapered FRP poles with flexible joints by an efficient one-dimensional FE model

Behnam Saboori,Seyed Mohammad Reza Khalili 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.59 No.2

This research develops a finite element code for the transient dynamic analysis of tapered fiber reinforced polymer (FRP) poles with hollow circular cross-section and flexible joints used in power transmission lines. The FRP poles are modeled by tapered beam elements and their flexible joints by a rotational spring. To solve the time equations of transient dynamic analysis, precise time integration method is utilized. In order to verify the utilized formulations, a typical jointed FRP pole under step, triangular and sine pulses is analyzed by the developed finite element code and also ANSYS commercial finite element software for comparison. Thereafter, the effect of joint flexibility on its dynamic behavior is investigated. It is observed that by increasing the joint stiffness, the amplitude of the pole tip deflection history decreases, and the time of occurrence of the maximum deflection is earlier.

Averaged strain energy density to assess mixed mode I/III fracture of U-notched GPPS samples

Behnam Saboori,A. R. Torabi,F. Berto,S. M. J. Razavi 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.6

In the present contribution, fracture resistance of U-notched GPPS members under mixed mode I/III loading conditions is assessed by using the Averaged Strain Energy Density (ASED) criterion. This criterion has been founded based on the ASED parameter averaged over a well-defined control volume embracing the notch edge. The validation of the theoretical criterion predictions is evaluated through comparing with the results of a series of mixed mode I/III fracture tests conducted on rectangular-shaped GPPS specimens weakened by a single edge U-notch. A recently developed apparatus for mixed mode I/III fracture experiments is employed for measuring the fracture loads of the specimens. The test samples are fabricated with different notch tip radii with the aim of evaluating the influence of this major feature of the U-notched components on the mixed mode I/III fracture behavior. It is shown that the onset of brittle fracture in U-notched GPPS specimens under various combinations of tension and out-of-plane shear can well be predicted by means of the ASED criterion.

Developing a New Risk Assessment Methodology for Distribution System Operators Regulated by Quality Regulation Considering Reclosing Time

S. Saboori deilami,Hamdi Abdi 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.4

In the restructured electricity market, Performance-Based Regulation (PBR) regimehas been introduced to the distribution network. To ensure the network stability, this regime is used along with quality regulations. Quality regulation impose new financial risks on distribution system operators (DSOs). The poor quality of the network will result in reduced revenues for DSOs. The mentioned financial risks depend on the quality indices of the system. Based on annual variation of these indices, the cost of quality regulation will also vary. In this paper with regard to reclosing fault in distribution network, we develop a risk-based method to assess the financial risks caused by quality regulation for DSOs. Furthermore, in order to take the stochastic behavior of the distribution network and quality indices variations into account, time-sequential Monte Carlo simulation method is used. Using the proposed risk method, the effect of taking reclosing time into account will be examined on system quality indicators and the cost of quality regulation in Swedish rural reliability test system (SRRTS). The results show that taking reclosing fault into consideration, affects the system quality indicators, particularly annual average interruption frequency index of the system (SAIFI). Moreover taking reclosing fault into consideration also affects the quality regulations cost. Therefore, considering reclosing time provides a more realistic viewpoint about the financial risks arising from quality regulation for DSOs.

The Influence of Purchasing Strategies on Company Performance: Oil and Gas Engineering and Construction Company Case Study

Saeed Amiri,Vafa Saboori-Deilami,Chang Seob Yeo,Morteza Mousakhani KINFORMS 2019 Management Review Vol.14 No.2

This research tries to determine the impact of various supply chain strategies and the impact of the company s interactions with suppliers on the firm s performance. The effect of these factors on the company s performance is analyzed using the structural equation modeling approach by partial least squares method (PLS). One of the main goals of a supply chain is to use a method that can bring the most and the best performance to the company. This paper reports on an applied research using survey method. 49 questions are designed to evaluate the variables. 7-point Likert scale is used to measure the questionnaire items. 300 completed questionnaires are collected and confirmed. In order to select the appropriate statistical method for testing the hypotheses, first the normality of the distribution of data has been tested using the Kolmogorov Smirnov method. Then, according to the results of this test, the nonparametric Spearman correlation coefficient and the structural equation modeling are used to analyze the data. The result of the hypothesis test shows a significant relationship between the variables. This study shows that the presence of a competitive business leads the company to invest in different situations in the supply chain, which improve company’s services and performance. In order to improve the company’s performance, managers also need to feel the need for long-term strategies for the supply chain that fits the overall business strategy rather than mid-term strategies. Researches show that it is very difficult to develop a single strategy in the purchasing process that can act as an all-inclusive strategy. Limitation to access company’s financial information is the main limitation of this research. Two types of purchase strategies were found in this research which could be the guide for Oil & Gas companies to impellent as their future purchasing strategies. The research has allowed testing and

Out-of-plane ductile failure of notch: Evaluation of Equivalent Material Concept

A. R. Torabi,Behnam Saboori,M. R. Kamjoo 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.75 No.5

In the present study, the fracture toughness of U-shaped notches made of aluminum alloy Al7075-T6 under combined tension/out-of-plane shear loading conditions (mixed mode I/III) is studied by theoretical and experimental methods. In the experimental part, U-notched test samples are loaded using a previously developed fixture under mixed mode I/III loading and their load-carrying capacity (LCC) is measured. Then, due to the presence of considerable plasticity in the notch vicinity at crack initiation instance, using the Equivalent Material Concept (EMC) and with the help of the point stress (PS) and mean stress (MS) brittle failure criteria, the LCC of the tested samples is predicted theoretically. The EMC equates a ductile material with a virtual brittle material in order to avoid performing elastic-plastic analysis. Because of the very good match between the EMC-PS and EMC-MS combined criteria with the experimental results, the use of the combination of the criteria with EMC is recommended for designing U-notched aluminum plates in engineering structures. Meanwhile, because of nearly the same accuracy of the two criteria and the simplicity of the PS criterion relations, the use of EMC-PS failure model in design of notched Al7075-T6 components is superior to the EMC-MS criterion.

Gene co-expression network reconstruction: a review on computational methods for inferring functional information from plant-based expression data

Abbasali Emamjomeh,Elham Saboori Robat,Javad Zahiri,Mahmood Solouki,Pegah Khosravi 한국식물생명공학회 2017 Plant biotechnology reports Vol.11 No.2

Reconstruction of gene co-expression networks is a powerful tool for better understanding of gene function, biological processes, and complex disease mechanisms. In essence, co-expression network analysis has been widely used for understanding which genes are highly co-expressed through special biological processes or differentially expressed in various conditions. Development of high-throughput experiments has provided a large amount of genomic and transcriptomic data for model and nonmodel organisms. The availability of genome-wide expression data has led to the development of in silico procedures for reconstruction of gene co-expression networks. Gene co-expression networks predict unknown genes’ functions; moreover, it has been successfully applied to understand important biological processes of living organisms such as plants. In this survey, we have reviewed the algorithms, databases, and tools of gene coexpression network reconstruction, which can lead to new landscapes for further research activities. Furthermore, we explain an application of some algorithms, databases, and tools that can significantly boost our current understanding of co-expression networks in Arabidopsis thaliana as a model plant using publicly available data. The presented example shows that using co-expression networks is an efficient way to detect genes, which may involve in various critical biological processes such as defense response.