Energy absorption optimization on a sandwich panel with lattice core under the low-velocity impact

Keramat Malekzadeh Fard,Meysam Mahmoudi 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.4

This paper focuses on the energy absorption of lattice core sandwich structures of different configurations. The diamond lattice unit cell, which has been extensively investigated for energy absorption applications, is the starting point for this research. The energy absorption behaviour of sandwich structures with an expanded metal sheet as the core is investigated at low-velocity impact loading. Numerical simulations were carried out using ABAQUS/EXPLICIT and the results were thoroughly compared with the experimental results, which indicated desirable accuracy. A parametric analysis, using a BoxBehnken design (BBD), as a method for the design of experiments (DOE), was performed. The samples fabricated in three levels of parameters include 0.081, 0.145, and 0.562 mm2 Cell sizes, and 0, 45, and 90-degree cell orientation, which were investigated. It was observed from experimental data that the angle of cells orientation had the highest degree of influence on the specific energy absorption. The results showed that the angle of cells orientation has been the most influential parameter to increase the peak forces. The results from using the design expert software showed the optimal specific energy absorption and peak force to be 1786 J/kg and 26314.4 N, respectively. The obtained R2 values and normal probability plots indicated a good agreement between the experimental results and those predicted by the model

Higher order static analysis of truncated conical sandwich panels with flexible cores

Keramat Malekzadeh Fard 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.19 No.6

A higher order analytical solution for static analysis of a truncated conical composite sandwich panel subjected to different loading conditions was presented in this paper which was based on a new improved higher order sandwich panel theory. Bending analysis of sandwich structures with flexible cores subjected to concentrated load, uniform distributed load on a patch, harmonic and uniform distributed loads on the top and/or bottom face sheet of the sandwich structure was also investigated. For the first time, bending analysis of truncated conical composite sandwich panels with flexible cores was performed. The governing equations were derived by principle of minimum potential energy. The first order shear deformation theory was used for the composite face sheets and for the core while assuming a polynomial description of the displacement fields. Also, the in-plane hoop stresses of the core were considered. In order to assure accuracy of the present formulations, convergence of the results was examined. Effects of types of boundary conditions, types of applied loads, conical angles and fiber angles on bending analysis of truncated conical composite sandwich panels were studied. As, there is no research on higher order bending analysis of conical sandwich panels with flexible cores, the results were validated by ABAQUS FE code. The present approach can be linked with the standard optimization programs and it can be used in the iteration process of the structural optimization. The proposed approach facilitates investigation of the effect of physical and geometrical parameters on the bending response of sandwich composite structures.

New enhanced higher order free vibration analysis of thick truncated conical sandwich shells with flexible cores

Keramat Malekzadeh Fard,Mostafa Livani 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.55 No.4

This paper dealt the free vibration analysis of thick truncated conical composite sandwich shells with transversely flexible cores and simply supported boundary conditions based on a new improved and enhanced higher order sandwich shell theory. Geometries were used in the present work for the consideration of different radii curvatures of the face sheets and the core was unique. The coupled governing partial differential equations were derived by the Hamilton's principle. The in-plane circumferential and axial stresses of the core were considered in the new enhanced model. The first order shear deformation theory was used for the inner and outer composite face sheets and for the core, a polynomial description of the displacement fields was assumed based on the second Frostig’s model. The effects of types of boundary conditions, conical angles, length to radius ratio, core to shell thickness ratio and core radius to shell thickness ratio on the free vibration analysis of truncated conical composite sandwich shells were also studied. Numerical results are presented and compared with the latest results found in literature. Also, the results were validated with those derived by ABAQUS FE code.

Investigation of anti-condensation strategies in the methanol synthesis reactor using computational fluid dynamics

Fatemeh Keramat,Azadeh Mirvakili,Alireza Shariati,Mohammad Reza Rahimpour 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.10

Flow mal-distribution in the shell side of the gas-cooled conventional reactor (CR) in the mega methanol plant is responsible for producing gas condensate in the catalytic zone. This phenomenon leads to catalyst agglomeration and efficiency reduction in the reactor. In this study, two novel and viable strategies, possible to be implemented in working reactors, are introduced to prevent condensation. In the first strategy, co-current mode (CCM), the reactant flow changes from counter-current into the co-current. In this regard, the feed inlet is replaced from the bottom of the reactor into the top. In the second strategy, changed-bed mode (CBM), the catalyst particles at the last two meters of the reactor are replaced with non-reactive ceramic balls. The results for three-dimensional computational fluid dynamics (CFD) in CR have been validated against previous study and industrial data, indicating close agreement. The main advantage of CCM and CBM is that the sudden temperature drop fails to occur at the end of the reactor. Consequently, the higher temperature of the products prevents water and methanol condensation. In addition, the CCM leads to a milder temperature profile throughout the shell side, which increases catalyst durability.

Seroprevalence of Brucellosis in Human Immunodeficiency Virus Infected Patients in Hamadan, Iran

Fariba Keramat,Mohammad Mehdi Majzobi,Jalal Poorolajal,Zohreh Zarei Ghane,Maryam Adabi 질병관리본부 2017 Osong Public Health and Research Persptectives Vol.8 No.4

Objectives: Brucellosis is a systemic disease with a wide spectrum of clinical manifestations. This study aimed to determine the seroprevalence of brucellosis in human immunodeficiency virus (HIV) infected patients in Hamadan Province in the west of Iran. Methods: A total of 157 HIV-infected patients were screened through standard serological tests, including Wright’s test, Coombs’ Wright test, and 2-mercaptoethanol Brucella agglutination test (2ME test), blood cultures in Castaneda media, and CD4 counting. Data were analyzed using Stata version 11. Results: Wright and Coombs’ Wright tests were carried out, and only 5 (3.2%) patients had positive serological results. However, all patients had negative 2ME results, and blood cultures were negative for Brucella spp. Moreover, patients with positive serology and a mean CD4 count of 355.8 ± 203.11 cells/mL had no clinical manifestations of brucellosis, and, and the other patients had a mean CD4 count of 335.55 ± 261.71 cells/mL. Conclusion: Results of this study showed that HIV infection is not a predisposing factor of acquiring brucellosis.

Effects of Dietary Supplementation with Immunogen® on the Growth, Hematology and Gut Microbiota of Fingerling Common Carp Cyprinus carpio (Linnaeus)

A. Keramat Amirkolaie,B. Rostami 한국수산과학회 2015 Fisheries and Aquatic Sciences Vol.18 No.4

We studied the effects of the proprietary prebiotic Immunogen® on the growth, hematology and gut microbiota of common carp fingerlings. A basal diet was formulated using common feed ingredients and supplemented with Immunogen® at concentrations of 0, 5, 10, 20 and 40 g kg–1, each of which was tested experimentally on replicated groups of fish. The trials ran for 8 weeks. Common carp fingerlings with an initial weight of 4.82 ± 0.05 g were randomly distributed among the experimental tanks at a stocking density of 25 fish per tank. The experimental diets were provided thrice per day; on each occasion the fingerlings were given a weight of feed that amounted to 4% of fish biomass. At the end of the experimental period, we determined the growth performance, feed conversion ratio, hematological parameters, body composition and gut micro-flora parameters of the test fish. Inclusion of 5 g kg–1Immunogen® in the diet significantly improved growth performance and feed utilization in comparison with controls. However, the whole-body composition of the fish was not significantly influenced by prebiotic inclusion. Inclusion of 5 g kg–1 Immunogen® significantly increased the total bacterial and Lactobacillus counts in fish intestines, but these bacterial parameters were significantly negatively impacted by higher concentrations of the prebiotic. Red blood cells counts were increased by prebiotic dietary supplementation at concentrations of 5 and 10 g kg–1 prebiotic. Glucose and cholesterol levels were elevated by administration of Immunogen®. Thus, dietary supplementation with 5 g kg–1 Immunogen® improved fingerling common carp growth performance and feed utilization, and beneficially influenced the gut microflora.

Effects of Dietary Supplementation with Immunogen^® on Growth, Hematology and Gut Microbiota of Fingerling Common Carp Cyprinus carpio

Amirkolaie, Keramat,Rostami, B. The Korean Society of Fisheries and Aquatic Scienc 2015 Fisheries and Aquatic Sciences Vol.18 No.4

We studied the effects of the proprietary prebiotic Immunogen$^{(R)}$ on the growth, hematology and gut microbiota of common carp fingerlings. A basal diet was formulated using common feed ingredients and supplemented with Immunogen$^{(R)}$ at concentrations of 0, 5, 10, 20 and $40g\;kg^{-1}$, each of which was tested experimentally on replicated groups of fish. The trials ran for 8 weeks. Common carp fingerlings with an initial weight of $4.82{\pm}0.05g$ were randomly distributed among the experimental tanks at a stocking density of 25 fish per tank. The experimental diets were provided thrice per day; on each occasion the fingerlings were given a weight of feed that amounted to 4% of fish biomass. At the end of the experimental period, we determined the growth performance, feed conversion ratio, hematological parameters, body composition and gut micro-flora parameters of the test fish. Inclusion of $5g\;kg^{-1}$Immunogen$^{(R)}$ in the diet significantly improved growth performance and feed utilization in comparison with controls. However, the whole-body composition of the fish was not significantly influenced by prebiotic inclusion. Inclusion of $5g\;kg^{-1}$ Immunogen$^{(R)}$ significantly increased the total bacterial and Lactobacillus counts in fish intestines, but these bacterial parameters were significantly negatively impacted by higher concentrations of the prebiotic. Red blood cells counts were increased by prebiotic dietary supplementation at concentrations of 5 and $10g\;kg^{-1}$ prebiotic. Glucose and cholesterol levels were elevated by administration of Immunogen$^{(R)}$. Thus, dietary supplementation with $5g\;kg^{-1}$ Immunogen$^{(R)}$ improved fingerling common carp growth performance and feed utilization, and beneficially influenced the gut microflora

Effects of fiber orientation and temperature on natural frequencies of a functionally graded beam reinforced with fiber

Mohammad Nejati,Keramat Malekzadeh Fard,Amir Hossein Eslampanah 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.8

In this paper, thermal vibrations of a reinforced orthotropic beam are studied. The beam is reinforced with fibers functionally orientedand graded along the thickness direction. Uniform thermal distribution is applied throughout the beam and property of the fiber functionallygraded beam considered temperature-dependent. Symmetrical, asymmetrical, and classical distributions are presented for variabilityof the angle of the fibers along the thickness direction. Equilibrium equations are employed to obtain the pre-stresses and equations ofmotion derived from first-order shear deformation theory and Hamilton principle. Generalized differential quadrature is used to solve thesystem of coupled differential equations. To verify the accuracy of the present analysis, compression is conducted with valid data. Resultsshow that different parameters, such as thickness-to-radius ratio, effect of temperature variations, distribution of the angle of the fibers,and different boundary conditions, influenced the beam effect on natural frequencies.

Breast Cancer Trend in Iran from 2000 to 2009 and Prediction till 2020 using a Trend Analysis Method

Zahmatkesh, Bibihajar,Keramat, Afsaneh,Alavi, Nasrinossadat,Khosravi, Ahmad,Kousha, Ahmad,Motlagh, Ali Ghanbari,Darman, Mahboobeh,Partovipour, Elham,Chaman, Reza Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.3

Background: Breast cancer is the most common cancer in women worldwide with a rising incidence rate in most countries. Considering the increase in life expectancy and change in lifestyle of Iranian women, this study investigated the age-adjusted trend of breast cancer incidence during 2000-2009 and predicted its incidence to 2020. Materials and Methods: The 1997 and 2006 census results were used for the projection of female population by age through the cohort-component method over the studied years. Data from the Iranian cancer registration system were used to calculate the annual incidence rate of breast cancer. The age-adjusted incidence rate was then calculated using the WHO standard population distribution. The five-year-age-specific incidence rates were also obtained for each year and future incidence was determined using the trend analysis method. Annual percentage change (APC) was calculated through the joinpoint regression method. Results: The bias adjusted incidence rate of breast cancer increased from 16.7 per 100,000 women in 2000 to 33.6 per 100,000 women in 2009. The incidence of breast cancer had a growing trend in almost all age groups above 30 years over the studied years. In this period, the age groups of 45-65 years had the highest incidence. Investigation into the joinpoint curve showed that the curve had a steep slope with an APC of 23.4% before the first joinpoint, but became milder after this. From 2005 to 2009, the APC was calculated as 2.7%, through which the incidence of breast cancer in 2020 was predicted as 63.0 per 100,000 women. Conclusions: The age-adjusted incidence rate of breast cancer continues to increas in Iranian women. It is predicted that this trend will continue until 2020. Therefore, it seems necessary to prioritize the prevention, control and care for breast cancer in Iran.

Higher order flutter analysis of doubly curved sandwich panels with variable thickness under aerothermoelastic loading

Mostafa livani,Keramat MalekzadehFard,Saeed Shokrollahi 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.60 No.1

In this study, the supersonic panel flutter of doubly curved composite sandwich panels with variable thickness is considered under aerothermoelastic loading. Considering different radii of curvatures of the face sheets in this paper, the thickness of the core is a function of plane coordinates (x,y), which is unique. For the first time in the current model, the continuity conditions of the transverse shear stress, transverse normal stress and transverse normal stress gradient at the layer interfaces, as well as the conditions of zero transverse shear stresses on the upper and lower surfaces of the sandwich panel are satisfied. The formulation is based on an enhanced higher order sandwich panel theory and the vertical displacement component of the face sheets is assumed as a quadratic one, while a cubic pattern is used for the in-plane displacement components of the face sheets and the all displacement components of the core. The formulation is based on the von Kármán nonlinear approximation, the one-dimensional Fourier equation of the heat conduction along the thickness direction, and the first-order piston theory. The equations of motion and boundary conditions are derived using the Hamilton principle and the results are validated by the latest results published in the literature.