The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Antanas Žiliukas - One of the best experts on this subject based on the ideXlab platform.
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THE CRASH ENERGY ABSORPTION OF THE VEHICLES FRONT STRUCTURES
TRANSPORT, 2003Co-Authors: Paulius Griškevičius, Antanas ŽiliukasAbstract:During the frontal crash the Longerons absorb most energy of all vehicles construction elements. In order to analyse the energy absorbing capabilities of Longerons under axial compression loading and to evaluate the influence of Longerons geometrical characteristics and materials degradation on the vehicles safety experimental investigations and numerical calculations were performed. To assess the crashworthiness of Longerons the main objective was to study the behaviour of thin-walled structural elements under axial loading conditions using the Finite Element (FE) model. The numerical FE models were created using the computer code LS-DYNA. Two models of Longerons were investigated with different sections shape and for each of them materials with the four different mechanical characteristics were applied. Validation of created FE model was performed according to the experimental investigation and the results were obtained of validated FE models of vehicles crash analysis [1]. The results of analyses show that the value of absorbed energy by the Longerons of new vehides exceeds the value of the oldest cars. The degradation of structures in the old cars has the significant influence on the absorbed energy.
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The crash energy absorption of the vehicles front structures
Transport, 2003Co-Authors: Paulius Griškevičius, Antanas ŽiliukasAbstract:Abstract During the frontal crash the Longerons absorb most energy of all vehicles construction elements. In order to analyse the energy absorbing capabilities of Longerons under axial compression loading and to evaluate the influence of Longerons geometrical characteristics and materials degradation on the vehicles safety experimental investigations and numerical calculations were performed. To assess the crashworthiness of Longerons the main objective was to study the behaviour of thin-walled structural elements under axial loading conditions using the Finite Element (FE) model. The numerical FE models were created using the computer code LS-DYNA. Two models of Longerons were investigated with different sections shape and for each of them materials with the four different mechanical characteristics were applied. Validation of created FE model was performed according to the experimental investigation and the results were obtained of validated FE models of vehicles crash analysis [1]. The results of analy...
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The crash energy absorption of the vehicles front structures
Vilnius Gedinimas Technical University, 2003Co-Authors: Paulius Griškevičius, Antanas ŽiliukasAbstract:During the frontal crash the Longerons absorb most energy of all vehicles construction elements. In order to analyse the energy absorbing capabilities of Longerons under axial compression loading and to evaluate the influence of Longerons geometrical characteristics and materials degradation on the vehicles safety experimental investigations and numerical calculations were performed. To assess the crashworthiness of Longerons the main objective was to study the behaviour of thin-walled structural elements under axial loading conditions using the Finite Element (FE) model. The numerical FE models were created using the computer code LS-DYNA. Two models of Longerons were investigated with different sections shape and for each of them materials with the four different mechanical characteristics were applied. Validation of created FE model was performed according to the experimental investigation and the results were obtained of validated FE models of vehicles crash analysis [1]. The results of analyses show that the value of absorbed energy by the Longerons of new vehides exceeds the value of the oldest cars. The degradation of structures in the old cars has the significant influence on the absorbed energy. First Published Online: 19 Dec 201
Zongquan Deng - One of the best experts on this subject based on the ideXlab platform.
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Model analysis and active vibration control for space deployable truss type mast
2011 IEEE International Conference on Mechatronics and Automation, 2011Co-Authors: Haojiang Zhao, Zongquan DengAbstract:Dynamic model of the large space deployable truss type mast is established. The first several natural frequencies, the vibration model shapes and the corresponding distribution of the Longerons model strain energy are given based on the analysis of the modes of the truss type mast. Use the distribution of the Longerons' model strain energy as an interpretational criterion to optimize actuator's placement. The independent modal space method and theory of quadratic optimal control are adopted to suppress the vibration of the truss type mast by MATLAB/SIMULINK simulation. The result shows that the control method is available.
Jinsong Leng - One of the best experts on this subject based on the ideXlab platform.
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Modal Analyses of Deployable Truss Structures Based on Shape Memory Polymer Composites
International Journal of Applied Mechanics, 2016Co-Authors: Liwu Liu, Xin Lan, Tong Wang, Li Xiangyu, Chen Fanlong, Wenfeng Bian, Yanju Liu, Jinsong LengAbstract:With large spatial deployable antennas used more widely, the stability of deployable antennas is attracting more attention. The form of the support structure is an important factor of the antenna’s natural frequency, which is essential to study to prevent the resonance. The deployable truss structures based on shape memory polymer composites (SMPCs) have made themselves feasible for their unique properties such as highly reliable, low-cost, light weight, and self-deployment without complex mechanical devices compared with conventional deployable masts. This study offers deliverables as follows: an establishment of three-longeron beam and three-longeron truss finite element models by using ABAQUS; calculation of natural frequencies and vibration modes; parameter studies for influence on their dynamic properties; manufacture of a three-longeron truss based on SMPC, and modal test of the three-longeron truss. The results show that modal test and finite element simulation fit well.
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Preliminary design and analysis of a cubic deployable support structure based on shape memory polymer composite
International Journal of Smart and Nano Materials, 2016Co-Authors: Liwu Liu, Xin Lan, Wenfeng Bian, Yanju Liu, Xiaojun Zhou, Jinsong LengAbstract:ABSTRACTThe deployable structures based on shape memory polymer composites (SMPCs) have been developed for its unique properties, such as high reliability, low-cost, lightweight, and self-deployment without complex mechanical devices compared with traditional deployable structures. In order to increase the inflatable structure system’s robustness and light the weight of it, a cubic deployable support structure based on SMPC is designed and analyzed preliminarily. The cubic deployable support structure based on SMPC consists of four dependent spatial cages, each spatial cage is composed of 12 three-longeron SMPC truss booms and end connections. The shape recovery of arc-shaped deployable laminates drive the three-longeron SMPC truss booms to unfold, thus realize the expansion of the deployable support structure. The concept and operation of the cubic deployable support structure are described in detail. A series of experiments are performed on the three-longeron deployable laminates unit and the simplified...
A. A. Shaniavski - One of the best experts on this subject based on the ideXlab platform.
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Scale levels for fatigue fracture mechanisms of in-service crack growth in Longerons of helicopter rotor blades
International Journal of Fracture, 2004Co-Authors: A. A. ShaniavskiAbstract:Cases of in-service fatigue crack growth in aluminium Longerons of helicopter Mi-8 rotor blades were reviewed. Fatigue fracture surface patterns for micro- and meso-scale levels of crack growth mechanisms for in-service fatigued Longerons are discussed. Meso-beach-marks were used to estimate the fatigue crack growth period in one of the damaged Longerons with the least crack size. Results of these estimations showed the effectiveness of the special device in in-service operation, which was used in Longerons for in-service fatigue crack detection.
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Quantitative fractographic analyses of fatigue crack growth in Longerons of in-service helicopter rotor-blades
Fatigue & Fracture of Engineering Materials and Structures, 1996Co-Authors: A. A. ShaniavskiAbstract:— An analysis is made of striation spacing measurements as observed on fatigue crack surfaces of specimens and Longerons of helicopter rotor-blades made from the aluminium alloy AVT. It is shown that, for the combined cyclic tensile stresses at various R-ratios and static rotation angles, α, striation spacings were controlled by an equivalent intensity factor Ke=K1F(α, R). Values of the F(α) for Ri= const were computed. The crack growth life in terms of the number of flights and stress equivalents were computed for various longeron sections of the helicopter rotor-blades which had failed in service. SUMMARY AND CONCLUSIONS (1) A fatigue striation spacing analysis was made from measurements on AVT Al-alloy specimens tested in air under combined cyclic tension and static-rotation loads at various a-angles of rotation, and stress ratios, R. Fractographic analyses have shown similarities in terms of striation spacing formation in the investigated range of α-angles and R ratios. (2) The similarity in the fatigue fracture mechanisms attested to the possibility of characterizing the striation spacing formation by a unified kinetic diagram via a Ke= K1F(α, R) approach for different α-angles and R ratios. The function F(α, R) was determined and it can be used to calculate the tensile stress equivalent according to values of σi measurements taken from components broken in tests or in service. (3) It was a longeron of the rotor-blade of helicopters manufactured from AVT Al-alloy broken in service and tested cyclically that were investigated fractographically. An analysis of the formation of striations and their spacing has shown similarities with the investigated Longerons fatigued in tests and in service. The crack growth life versus number of flights and stress equivalent was calculated according to values of the σi measurements. (4) It was shown that a fatigue crack will not nucleate in Longerons in service if the depth of defects on the external surface have a size less than 0.3 mm. The stress for tested Longerons is near to the calculated equivalent for Longerons that failed in service.
Stráník Radim - One of the best experts on this subject based on the ideXlab platform.
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Parametric study of the absorption element of the frontal vehicle part from the passangers safety point of view during the frontal car collision
Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016Co-Authors: Stráník RadimAbstract:The main subject of this master thesis is the computational modeling of stress-strain analysis of the loaded front part of Toyota Yaris from the year 2010 using an explicit finite element method (FEM). The aim of this thesis is the assessment of resistance of the front part of the car (longeron) at the impact stress. This thesis describes the selection, editing, and creation of the computational model of longeron and simulation of the barrier collision. The objective of the thesis is to use a real vehicle, suggest modified Longerons to be implemented in it, test various shape and material versions of the longeron and make their comparison
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Parametric study of the absorption element of the frontal vehicle part from the passangers safety point of view during the frontal car collision
Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016Co-Authors: Stráník RadimAbstract:Diplomová práce se zabývá výpočtovým modelováním deformačně-napěťových stavů zatížené přední části automobilu Toyota Yaris z roku 2010 s využitím explicitního přístupu metody konečných prvků (MKP). Cílem této práce je posouzení odolnosti přední části vozu konkrétně podélníků při tomto rázovém namáhání. Práce popisuje výběr, úpravu a tvorbu výpočtového modelu podélníků a simulaci nárazu na bariéru. Smyslem bylo využít reálné vozidlo, navrhnout do něj modifikované podélníky, vyzkoušet různé tvarové a materiálové provedení a vzájemně dané varianty srovnat.The main subject of this master thesis is the computational modeling of stress-strain analysis of the loaded front part of Toyota Yaris from the year 2010 using an explicit finite element method (FEM). The aim of this thesis is the assessment of resistance of the front part of the car (longeron) at the impact stress. This thesis describes the selection, editing, and creation of the computational model of longeron and simulation of the barrier collision. The objective of the thesis is to use a real vehicle, suggest modified Longerons to be implemented in it, test various shape and material versions of the longeron and make their comparison.
