camelia Cerbu - Academia.edu (original) (raw)
Papers by camelia Cerbu
Polymers, Dec 29, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
IOP conference series, Sep 19, 2018
This paper researches the reduction of the general / overall torsion of multi-story, rectangular,... more This paper researches the reduction of the general / overall torsion of multi-story, rectangular, reinforced concrete structures. The general torsion is caused by the distance (eccentricity) between the centre of stiffness and the centre of mass of the structure. During the seismic shaking of the structural systems, the inertia force acts through the centre of mass, while the resistive force acts through the centre of stiffness. Under this coupled lateraltorsional motion, structural members located along the perimeter of the buildings develop increased deformations and stresses due to buildings' twisting, which results in a higher risk of collapse (brittle, non-ductile failure, damage). This leads to the torsional behaviour of buildings, which is one of the most frequent sources of structural damage and failure during strong ground motions. This paper investigates the influence of the cross sectional properties of the structural components / members, to reduce the above mentioned effect as much as possible. The reduction of the eccentricity can be obtained by modifying cross sectional properties of some rectangular reinforced concrete walls, such as the moment of inertia (length and width of the reinforced concrete walls), which are asymmetrically arranged relative to the central reinforced concrete core. The position of these rectangular reinforced concrete walls is known. Finding the optimal height and width of these walls can be done by using a MatLab function, which minimizes the distance between the centre of stiffness and the centre of mass. The obtained results are then verified in a structural software (ETABS 2016), using modal analysis, or the mode-superposition method, to determine the mode shapes of the structure.
Review of Artistic Education
The paper presents the interdisciplinary approach of two fields - the artistic (musical) and tech... more The paper presents the interdisciplinary approach of two fields - the artistic (musical) and technical (forestry engineering, wood processing engineering, mechanical and physical engineering) apparently opposite but which can be happily exploited for both parties. Thus, we can speak of a new paradigm of education through which art can combine with the technical sciences for the benefit of all. The aim of the paper is to present experimental methods in mechanical and acoustic evaluation of violins from engineering and artistic perspectives. The presented results are part of a larger study carried out within an experimental demonstration research project.
Proceedings in automotive engineering, Sep 30, 2018
The trends in the automotive field aim at providing all users with a high level of safety and a h... more The trends in the automotive field aim at providing all users with a high level of safety and a high degree of comfort. Current technologies combine increasingly judicious optimal control of most systems in the their componing. Thus, the highest level electronic equipment permanently adjusts the various systems and subsystems of the vehicles. The aim of the research is to determine optimal MRD functionality to reduce extreme shock and vibration values at the driver’s seat during unbuilt or very rough roads. Also, the identifying of these values its to view of correctly determining the supply current of the shock absorber coil so that the magnetic force created can efficiently absorb the accelerations produced beyond the limits allowed by the international standards in force. Carrying out the research involves multiple laboratory tests on MRD using the Hidropuls type, but also some references to vertical seat accelerations values recorded in the real world. The expected results are to reduce physical activity on the spine, as well as increasing the comfort of the seated staff.
Forests
This paper presents the investigations conducted on three types of fibre-reinforced epoxy-resin h... more This paper presents the investigations conducted on three types of fibre-reinforced epoxy-resin hybrid composites with different structures, manufactured using midrib long fibres of date palm (Phoenix dactylifera L.) and Calotropis procera fibres. The two types of fibres were formed into flat sheets, without adding other chemicals or resins, and employed as reinforcing layers in the structure of the multi-layered laminate composites. Three-layer and five-layer epoxy-reinforced laminates were manufactured from the sheets of date-palm fibres and Calotropis sheets bonded with laminar epoxy resin. Water resistance investigation and mechanical testing under tensile, bending and impact loads were conducted in the research in order to evaluate and compare the performance of the resulting composites. Emphasis was put on the effect of various factors, such as the type of reinforcement material and the number of plies in the laminate on the mechanical behavior of the composites. The interpret...
Materials
In large metal civil constructions (stadium roofs, bridges), slender bars can lose their stabilit... more In large metal civil constructions (stadium roofs, bridges), slender bars can lose their stability under compression loading. There is a lack in the literature regarding design solutions and methods for increasing the critical buckling force of bars with variable cross-sections. The aim of this research is to present a numerical model with finite elements used for a comparative analysis of increasing the critical force of stability loss in cases of (i) bars with stepwise variation in the cross-sections and (ii) bars with continuous variation in the moment of inertia along the bar axis (parabolic, sinusoidal, triangular, and trapezoidal variation). Considering the large-scale applications in civil engineering, bars that were pin-connected at one end and simple-supported at the other end were analyzed. Firstly, the analytical model was described to compute the critical buckling force for bars with stepwise variation in the cross-sections. Then, a finite element model for a slender bar...
Polymers
As hybrid carbon-aramid composites become widely used in various industries, it has become impera... more As hybrid carbon-aramid composites become widely used in various industries, it has become imperative to mechanically characterize them using accurate methods of measuring the entire deformation field such as the digital image correlation (DIC) method. The accuracy of the numerical simulation of carbon-aramid composite structures depends on the accuracy of the elastic constants. Therefore, the goal of this research is to model and simulate the mechanical behaviour of the composite based on epoxy resin reinforced with carbon-aramid woven fabric by considering the mechanical properties investigated by tensile test combined with DIC and the bending test. The curves of the transverse strains related to the longitudinal strains were investigated using DIC in order to determine the Poisson’s ratios in the case of tensile tests applied in warp or weft directions of the reinforcement fabric. The impact strength determined by Charpy tests is also reported. The other main objective is to use ...
In this paper, the mechanical behaviour of the laminated composite panels reinforced with both wo... more In this paper, the mechanical behaviour of the laminated composite panels reinforced with both woven glass fabric and wood flour was investigated, during the low velocity impact test. A drop-weight test device was used for this purpose. In order to assess the response parameters, a block diagram was designed using LabView program. Five rectangular composite panels were investigated, simply supported on all edges. All panels had the same structure of materials: seven layers of glass woven fabric / epoxy resin and oak wood flour as the filler material on the interface of the layers. The effects of the different impact velocities on the mechanical behaviour of these composite panels were analyzed.
The paper analyses the effects of the type of resin on the impact characteristics in case of four... more The paper analyses the effects of the type of resin on the impact characteristics in case of four composite materials randomly reinforced with E-glass chopped fibres. Therefore, four kinds of polymer resins were used to manufacture the composite materials: polyester Heliopol 8431 ATX, polyester Polylite 440-M880, and epoxy LY 554, vinyl-ester ATLAC582. The volume ratio of E-glass fibres was the same for each composite analysed. The specimens for Charpy test were cut from the composite plates. The paper presents and analyses the results of the Charpy tests (failure energy U and resilience K) in case of the composite materials tested. Some important remarks concerning the areas of failure are presented. Finally, the paper graphically shows the effects of the resin type on the dynamical characteristics obtained in Charpy test.
Materials
The worldwide use of pallet racking storage systems leads to the necessity for research regarding... more The worldwide use of pallet racking storage systems leads to the necessity for research regarding the effects of the clearance between the metallic tabs of the connector and upright slots (looseness effect) on the performance of load-bearing beams. Firstly, the looseness angle and the rotational stiffness were experimentally obtained for three types of beam-to-upright connections. A theoretical approach is used to investigate the magnitude of the looseness effects that occurred on the performances of the bearing beam of the pallet storage systems in terms of the bending moment developed at the midpoint of the beam and maximum deflection. Calculation corrections were evaluated for the connections involved in the experimental part, for the case which considers the looseness effects with respect to the case which does not consider the looseness effect. In order to evaluate the effects of the parameters of the connections on calculus corrections, the theoretical model was used for other...
Rezumat: În acest articol s-a cercetat comportarea mecanică a plăcilor din materiale compozite st... more Rezumat: În acest articol s-a cercetat comportarea mecanică a plăcilor din materiale compozite stratificate ranforsate atât cu Ńesătură din fibre de sticlă cât şi cu făină de lemn, în timpul încercării de impact cu viteză mică. În acest scop, s-a utilizat un dispozitiv de încercare prin căderea greutăŃii. Pentru a evalua parametrii de răspuns, o diagramă bloc a fost făcută utilizând programul LabView. Cercetarea a fost efectuată pe cinci plăci compozite având formă dreptunghiulară, rezemate pe toate marginile. Toate plăcile au avut aceeaşi structură de material: şapte straturi fabricate din Ńesătură din fibre de sticlă / răşină epoxi şi făină de lemn de stejar ca material de umplutură la interfaŃa dintre straturi. S-au analizat efectele diferitelor viteze de impact asupra comportării mecanice în cazul acestor plăci compozite.
It is known that the moisture content may affects the mechanical characteristics of the composite... more It is known that the moisture content may affects the mechanical characteristics of the composite materials. The principal objective of this paper is to optimise from material point of view, the rear plate of a motorboat hull made of composite material. An additional criterion of optimisation concerning the conservation of the mechanical properties under the action of the moisture, was considered. Three E-glass reinforced composites were considered to analyse mechanical behaviour of the rear plate of a motorboat hull. From material point of view, the structural optimization of the rear plate of the motorboat analysed, leads to the conclusion that E-glass / polyester Polylite 440-M880 or E-glass / vinyl-ester Atlac 582 should be used to manufacture this member.
In this paper, the rear plate of a motorboat hull made of randomly E-glass fibres reinforced poly... more In this paper, the rear plate of a motorboat hull made of randomly E-glass fibres reinforced polymeric resin is analysed. A numerical model of the rear plate of a motorboat hull is proposed by using the method of finite elements. Stresses and strains occurred due to the action of the drag force developed by the motor of the boat, were analysed in case of four kinds of composite materials. Then, the strains about three directions in five points of the rear plate of the motorboat hull made of E-glass / Polylite 440-M880 composite, were measured by using five bonded strain gauges. The experimental strains and theoretical strains measured in the same points on the numerical model, were compared in case of the drag forces of 294.3 N and 392.4 N. The experimental errors were less than 5-6 % (only four errors were between 5 and 6 %). The results lead us to the conclusion that the theoretical model of the rear plate, may be used to optimise it. From rigidity point of view, it is shown that ...
The paper describes aspects concerning the effects of the water absorption on some mechanical cha... more The paper describes aspects concerning the effects of the water absorption on some mechanical characteristics of some composite materials reinforced with E-glass woven fabrics. The specimens were manufactured by reinforcing a polyester resin Copoly 7233 with both woven fabric EWR300 made of E-glass fibres and chopped E-glass fibres. The hand lay-up technology was used to manufacture the specimens with different pressures in the moulding step: low pressure and high pressure, respectively. The first of all, some specimens were immersed in water and the data regarding the moisture content were periodically recorded. Then, both dried specimens and wet specimens were subjected to the tensile test after 3500 hours of immersion. Finally, the experimental results obtained in case of the immersed specimens were comparatively analysed with the results recorded in case of the dried specimens subjected to the tensile test too. Moreover, the mechanical characteristics of the specimens were analy...
Some composite materials reinforced with E-glass woven fabrics or / and E-glass chopped fibres ar... more Some composite materials reinforced with E-glass woven fabrics or / and E-glass chopped fibres are considered. Three types of woven fabrics made of E-glass fibres, were used to reinforce an epoxy resin (RAKO-TOOL EH-2900) and composite plates were prepared. One of composite plates was additionally reinforced with E-glass chopped fibres. Then, 30 specimens for Charpy test were manufactured from the composite plates. The paper presents and analyses the results of the Charpy test (failure energy U and resilience K) in case of the composite materials tested. Some important remarks concerning the failure are presented. Finally, the paper notes the advantages of the supplementary reinforce with E-glass chopped fibres.
Procedia Technology, 2015
Woven Fabric Engineering, 2010
The paper describes the aspects concerning the effects of the manufacturing process on the mechan... more The paper describes the aspects concerning the effects of the manufacturing process on the mechanical characteristics of some E-glass / epoxy composites. In this paper, the specimens were manufactured by reinforcing an epoxy resin with woven fabric EWR300 made of E-glass fibres. Some characteristics of this kind of woven fabric, are known: weight, thickness, minimum tensile strength. The hand lay-up technology is used to prepare the specimens with different pressures in the molding step: low and high pressure. Then, the composite specimens were subjected to the flexural test (three points method). Herein, the mechanical characteristics of the specimens were analysed taking into account the different manufacture methods used. A comparison concerning the results obtained in cases of the two kinds of reinforcements used, will be also shown.
Polymers, Dec 29, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
IOP conference series, Sep 19, 2018
This paper researches the reduction of the general / overall torsion of multi-story, rectangular,... more This paper researches the reduction of the general / overall torsion of multi-story, rectangular, reinforced concrete structures. The general torsion is caused by the distance (eccentricity) between the centre of stiffness and the centre of mass of the structure. During the seismic shaking of the structural systems, the inertia force acts through the centre of mass, while the resistive force acts through the centre of stiffness. Under this coupled lateraltorsional motion, structural members located along the perimeter of the buildings develop increased deformations and stresses due to buildings' twisting, which results in a higher risk of collapse (brittle, non-ductile failure, damage). This leads to the torsional behaviour of buildings, which is one of the most frequent sources of structural damage and failure during strong ground motions. This paper investigates the influence of the cross sectional properties of the structural components / members, to reduce the above mentioned effect as much as possible. The reduction of the eccentricity can be obtained by modifying cross sectional properties of some rectangular reinforced concrete walls, such as the moment of inertia (length and width of the reinforced concrete walls), which are asymmetrically arranged relative to the central reinforced concrete core. The position of these rectangular reinforced concrete walls is known. Finding the optimal height and width of these walls can be done by using a MatLab function, which minimizes the distance between the centre of stiffness and the centre of mass. The obtained results are then verified in a structural software (ETABS 2016), using modal analysis, or the mode-superposition method, to determine the mode shapes of the structure.
Review of Artistic Education
The paper presents the interdisciplinary approach of two fields - the artistic (musical) and tech... more The paper presents the interdisciplinary approach of two fields - the artistic (musical) and technical (forestry engineering, wood processing engineering, mechanical and physical engineering) apparently opposite but which can be happily exploited for both parties. Thus, we can speak of a new paradigm of education through which art can combine with the technical sciences for the benefit of all. The aim of the paper is to present experimental methods in mechanical and acoustic evaluation of violins from engineering and artistic perspectives. The presented results are part of a larger study carried out within an experimental demonstration research project.
Proceedings in automotive engineering, Sep 30, 2018
The trends in the automotive field aim at providing all users with a high level of safety and a h... more The trends in the automotive field aim at providing all users with a high level of safety and a high degree of comfort. Current technologies combine increasingly judicious optimal control of most systems in the their componing. Thus, the highest level electronic equipment permanently adjusts the various systems and subsystems of the vehicles. The aim of the research is to determine optimal MRD functionality to reduce extreme shock and vibration values at the driver’s seat during unbuilt or very rough roads. Also, the identifying of these values its to view of correctly determining the supply current of the shock absorber coil so that the magnetic force created can efficiently absorb the accelerations produced beyond the limits allowed by the international standards in force. Carrying out the research involves multiple laboratory tests on MRD using the Hidropuls type, but also some references to vertical seat accelerations values recorded in the real world. The expected results are to reduce physical activity on the spine, as well as increasing the comfort of the seated staff.
Forests
This paper presents the investigations conducted on three types of fibre-reinforced epoxy-resin h... more This paper presents the investigations conducted on three types of fibre-reinforced epoxy-resin hybrid composites with different structures, manufactured using midrib long fibres of date palm (Phoenix dactylifera L.) and Calotropis procera fibres. The two types of fibres were formed into flat sheets, without adding other chemicals or resins, and employed as reinforcing layers in the structure of the multi-layered laminate composites. Three-layer and five-layer epoxy-reinforced laminates were manufactured from the sheets of date-palm fibres and Calotropis sheets bonded with laminar epoxy resin. Water resistance investigation and mechanical testing under tensile, bending and impact loads were conducted in the research in order to evaluate and compare the performance of the resulting composites. Emphasis was put on the effect of various factors, such as the type of reinforcement material and the number of plies in the laminate on the mechanical behavior of the composites. The interpret...
Materials
In large metal civil constructions (stadium roofs, bridges), slender bars can lose their stabilit... more In large metal civil constructions (stadium roofs, bridges), slender bars can lose their stability under compression loading. There is a lack in the literature regarding design solutions and methods for increasing the critical buckling force of bars with variable cross-sections. The aim of this research is to present a numerical model with finite elements used for a comparative analysis of increasing the critical force of stability loss in cases of (i) bars with stepwise variation in the cross-sections and (ii) bars with continuous variation in the moment of inertia along the bar axis (parabolic, sinusoidal, triangular, and trapezoidal variation). Considering the large-scale applications in civil engineering, bars that were pin-connected at one end and simple-supported at the other end were analyzed. Firstly, the analytical model was described to compute the critical buckling force for bars with stepwise variation in the cross-sections. Then, a finite element model for a slender bar...
Polymers
As hybrid carbon-aramid composites become widely used in various industries, it has become impera... more As hybrid carbon-aramid composites become widely used in various industries, it has become imperative to mechanically characterize them using accurate methods of measuring the entire deformation field such as the digital image correlation (DIC) method. The accuracy of the numerical simulation of carbon-aramid composite structures depends on the accuracy of the elastic constants. Therefore, the goal of this research is to model and simulate the mechanical behaviour of the composite based on epoxy resin reinforced with carbon-aramid woven fabric by considering the mechanical properties investigated by tensile test combined with DIC and the bending test. The curves of the transverse strains related to the longitudinal strains were investigated using DIC in order to determine the Poisson’s ratios in the case of tensile tests applied in warp or weft directions of the reinforcement fabric. The impact strength determined by Charpy tests is also reported. The other main objective is to use ...
In this paper, the mechanical behaviour of the laminated composite panels reinforced with both wo... more In this paper, the mechanical behaviour of the laminated composite panels reinforced with both woven glass fabric and wood flour was investigated, during the low velocity impact test. A drop-weight test device was used for this purpose. In order to assess the response parameters, a block diagram was designed using LabView program. Five rectangular composite panels were investigated, simply supported on all edges. All panels had the same structure of materials: seven layers of glass woven fabric / epoxy resin and oak wood flour as the filler material on the interface of the layers. The effects of the different impact velocities on the mechanical behaviour of these composite panels were analyzed.
The paper analyses the effects of the type of resin on the impact characteristics in case of four... more The paper analyses the effects of the type of resin on the impact characteristics in case of four composite materials randomly reinforced with E-glass chopped fibres. Therefore, four kinds of polymer resins were used to manufacture the composite materials: polyester Heliopol 8431 ATX, polyester Polylite 440-M880, and epoxy LY 554, vinyl-ester ATLAC582. The volume ratio of E-glass fibres was the same for each composite analysed. The specimens for Charpy test were cut from the composite plates. The paper presents and analyses the results of the Charpy tests (failure energy U and resilience K) in case of the composite materials tested. Some important remarks concerning the areas of failure are presented. Finally, the paper graphically shows the effects of the resin type on the dynamical characteristics obtained in Charpy test.
Materials
The worldwide use of pallet racking storage systems leads to the necessity for research regarding... more The worldwide use of pallet racking storage systems leads to the necessity for research regarding the effects of the clearance between the metallic tabs of the connector and upright slots (looseness effect) on the performance of load-bearing beams. Firstly, the looseness angle and the rotational stiffness were experimentally obtained for three types of beam-to-upright connections. A theoretical approach is used to investigate the magnitude of the looseness effects that occurred on the performances of the bearing beam of the pallet storage systems in terms of the bending moment developed at the midpoint of the beam and maximum deflection. Calculation corrections were evaluated for the connections involved in the experimental part, for the case which considers the looseness effects with respect to the case which does not consider the looseness effect. In order to evaluate the effects of the parameters of the connections on calculus corrections, the theoretical model was used for other...
Rezumat: În acest articol s-a cercetat comportarea mecanică a plăcilor din materiale compozite st... more Rezumat: În acest articol s-a cercetat comportarea mecanică a plăcilor din materiale compozite stratificate ranforsate atât cu Ńesătură din fibre de sticlă cât şi cu făină de lemn, în timpul încercării de impact cu viteză mică. În acest scop, s-a utilizat un dispozitiv de încercare prin căderea greutăŃii. Pentru a evalua parametrii de răspuns, o diagramă bloc a fost făcută utilizând programul LabView. Cercetarea a fost efectuată pe cinci plăci compozite având formă dreptunghiulară, rezemate pe toate marginile. Toate plăcile au avut aceeaşi structură de material: şapte straturi fabricate din Ńesătură din fibre de sticlă / răşină epoxi şi făină de lemn de stejar ca material de umplutură la interfaŃa dintre straturi. S-au analizat efectele diferitelor viteze de impact asupra comportării mecanice în cazul acestor plăci compozite.
It is known that the moisture content may affects the mechanical characteristics of the composite... more It is known that the moisture content may affects the mechanical characteristics of the composite materials. The principal objective of this paper is to optimise from material point of view, the rear plate of a motorboat hull made of composite material. An additional criterion of optimisation concerning the conservation of the mechanical properties under the action of the moisture, was considered. Three E-glass reinforced composites were considered to analyse mechanical behaviour of the rear plate of a motorboat hull. From material point of view, the structural optimization of the rear plate of the motorboat analysed, leads to the conclusion that E-glass / polyester Polylite 440-M880 or E-glass / vinyl-ester Atlac 582 should be used to manufacture this member.
In this paper, the rear plate of a motorboat hull made of randomly E-glass fibres reinforced poly... more In this paper, the rear plate of a motorboat hull made of randomly E-glass fibres reinforced polymeric resin is analysed. A numerical model of the rear plate of a motorboat hull is proposed by using the method of finite elements. Stresses and strains occurred due to the action of the drag force developed by the motor of the boat, were analysed in case of four kinds of composite materials. Then, the strains about three directions in five points of the rear plate of the motorboat hull made of E-glass / Polylite 440-M880 composite, were measured by using five bonded strain gauges. The experimental strains and theoretical strains measured in the same points on the numerical model, were compared in case of the drag forces of 294.3 N and 392.4 N. The experimental errors were less than 5-6 % (only four errors were between 5 and 6 %). The results lead us to the conclusion that the theoretical model of the rear plate, may be used to optimise it. From rigidity point of view, it is shown that ...
The paper describes aspects concerning the effects of the water absorption on some mechanical cha... more The paper describes aspects concerning the effects of the water absorption on some mechanical characteristics of some composite materials reinforced with E-glass woven fabrics. The specimens were manufactured by reinforcing a polyester resin Copoly 7233 with both woven fabric EWR300 made of E-glass fibres and chopped E-glass fibres. The hand lay-up technology was used to manufacture the specimens with different pressures in the moulding step: low pressure and high pressure, respectively. The first of all, some specimens were immersed in water and the data regarding the moisture content were periodically recorded. Then, both dried specimens and wet specimens were subjected to the tensile test after 3500 hours of immersion. Finally, the experimental results obtained in case of the immersed specimens were comparatively analysed with the results recorded in case of the dried specimens subjected to the tensile test too. Moreover, the mechanical characteristics of the specimens were analy...
Some composite materials reinforced with E-glass woven fabrics or / and E-glass chopped fibres ar... more Some composite materials reinforced with E-glass woven fabrics or / and E-glass chopped fibres are considered. Three types of woven fabrics made of E-glass fibres, were used to reinforce an epoxy resin (RAKO-TOOL EH-2900) and composite plates were prepared. One of composite plates was additionally reinforced with E-glass chopped fibres. Then, 30 specimens for Charpy test were manufactured from the composite plates. The paper presents and analyses the results of the Charpy test (failure energy U and resilience K) in case of the composite materials tested. Some important remarks concerning the failure are presented. Finally, the paper notes the advantages of the supplementary reinforce with E-glass chopped fibres.
Procedia Technology, 2015
Woven Fabric Engineering, 2010
The paper describes the aspects concerning the effects of the manufacturing process on the mechan... more The paper describes the aspects concerning the effects of the manufacturing process on the mechanical characteristics of some E-glass / epoxy composites. In this paper, the specimens were manufactured by reinforcing an epoxy resin with woven fabric EWR300 made of E-glass fibres. Some characteristics of this kind of woven fabric, are known: weight, thickness, minimum tensile strength. The hand lay-up technology is used to prepare the specimens with different pressures in the molding step: low and high pressure. Then, the composite specimens were subjected to the flexural test (three points method). Herein, the mechanical characteristics of the specimens were analysed taking into account the different manufacture methods used. A comparison concerning the results obtained in cases of the two kinds of reinforcements used, will be also shown.