scholarly journals Numerical Simulations of Post-Critical Behaviour of Thin- Walled Load-Bearing Structures Applied in Aviation

10.5772/57218 ◽  
2014 ◽  
Author(s):  
Tomasz Kopecki
Keyword(s):  
Numerical Simulations ◽  
Critical Behaviour ◽  
Load Bearing ◽  
Thin Walled

Numerical and Experimental Analyses of Free and Forced Vibration of Thin-Walled Beams

2020 ◽  
pp. 2150018
Author(s):  
Wassim Jrad ◽  
Foudil Mohri ◽  
Guillaume Robin ◽  
El Mostafa Daya
Keyword(s):  
Numerical Simulations ◽  
Present Model ◽  
Natural Frequencies ◽  
Response Spectra ◽  
Test Results ◽  
The Finite Element Method ◽  
Coupled Modes ◽  
Free And Forced Vibrations ◽  
Commercial Code ◽  
Thin Walled

The flexural–torsional vibration behavior of unrestrained and braced thin-walled beams is investigated by experimental and finite elements approaches. In the experimental part, tests in free and forced vibrations of thin walled beams with arbitrary sections are analyzed. By the help of an instrumental hammer test and a shaker machine, the natural frequencies and the response spectra of the beams are extracted in the range 1–400[Formula: see text]Hz. Beam displacements are measured by some accelerometer transducers. The behavior is also investigated by the finite element method. In mesh process, 3D beams are adopted and an additional DOF is affected to the warping. The model is implemented in a home-made model. The numerical and experimental results are compared to numerical simulations of a commercial code. Test results and numerical simulations of the present model agree well. The model seems to be accurate especially in the presence of higher vibration and coupled modes.

Ron Resch Origami Pattern Inspired Energy Absorption Structures

2018 ◽  
Vol 86 (1) ◽  
Author(s):  
Zhe Chen ◽  
Tonghao Wu ◽  
Guodong Nian ◽  
Yejie Shan ◽  
Xueya Liang ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Energy Absorption ◽  
Impact Energy ◽  
Plastic Hinge ◽  
Honeycomb Structure ◽  
Experimental Characterization ◽  
Collapse Mode ◽  
Thin Walled ◽  
Force Reduction ◽  
Absorb Impact Energy

Energy absorption structures are widely used in many scenarios. Thin-walled members have been heavily employed to absorb impact energy. This paper presents a novel, Ron Resch origami pattern inspired energy absorption structure. Experimental characterization and numerical simulations were conducted to study the energy absorption of this structure. The results show a new collapse mode in terms of energy absorption featuring multiple plastic hinge lines, which lead to the peak force reduction and larger effective stroke, as compared with the classical honeycomb structure. Overall, the Ron Resch origami-inspired structure and the classical honeycomb structure are quite complementary as energy absorption structures.

scholarly journals Avalanche transmission and critical behaviour in load-bearing hierarchical networks

Pramana ◽  
2011 ◽  
Vol 77 (5) ◽  
pp. 873-879 ◽  
Author(s):  
AJAY DEEP KACHHVAH ◽  
NEELIMA GUPTE
Keyword(s):  
Critical Behaviour ◽  
Hierarchical Networks ◽  
Load Bearing

Structural bionic design for thin-walled cylindrical shell against buckling under axial compression

2011 ◽  
Vol 225 (11) ◽  
pp. 2619-2627 ◽  
Author(s):  
D Xing ◽  
W Chen ◽  
J Ma ◽  
L Zhao
Keyword(s):  
Cylindrical Shell ◽  
Axial Compression ◽  
Cross Section ◽  
Cylindrical Shells ◽  
High Load ◽  
Vascular Bundles ◽  
Bionic Design ◽  
Load Bearing ◽  
Thin Walled ◽  
The Cross

In nature, bamboo develops an excellent structure to bear nature forces, and it is very helpful for designing thin-walled cylindrical shells with high load-bearing efficiency. In this article, the cross-section of bamboo is investigated, and the feature of the gradual distribution of vascular bundles in bamboo cross-section is outlined. Based on that, a structural bionic design for thin-walled cylindrical shells is presented, of which the manufacturability is also taken into consideration. The comparison between the bionic thin-walled cylindrical shell and a simple hollow one with the same weight showed that the load-bearing efficiency was improved by 44.7 per cent.

Explicit Finite Element Analyses of Drop Tests With Thin-Walled Steel Sheet Containers for the Konrad Repository

2015 ◽  
Author(s):  
Christian Protz ◽  
Uwe Zencker ◽  
Robert Liebich
Keyword(s):  
Finite Element ◽  
Numerical Simulations ◽  
Damage Mechanics ◽  
Steel Sheet ◽  
Assessment Procedure ◽  
Fe Model ◽  
Explicit Finite Element ◽  
Safety Margins ◽  
Drop Tests ◽  
Thin Walled

Alternatively to experimental drop tests, the mechanical safety analyses of containers for final disposal of radioactive waste with negligible heat generation in the German Konrad repository may be carried out by numerical simulations within the safety assessment procedure. In the past, safety assessments for thin-walled steel sheet containers have been done exclusively by prototype tests and unfavorable drop scenarios were determined by engineering judgment. So far, reliable numerical simulations do not exist. Therefore, a research project was started to develop numerical simulation approaches for drop test analyses and to determine existing safety margins. Comparisons of experimental and numerical results confirm that the Finite Element (FE) model represents the general mechanical behavior of the steel sheet container sufficiently. Simulations have been used to determine an unfavorable drop scenario resulting in large deformation and damage. This paper presents the investigations carried out as well as the further development of the FE model in terms of damage mechanics.

scholarly journals BEHAVIOUR OF VERTICAL CYLINDRICAL TANK WITH LOCAL WALL IMPERFECTIONS

2019 ◽  
Vol 25 (3) ◽  
pp. 287-296 ◽  
Author(s):  
Antanas Šapalas ◽  
Gintas Šaučiuvėnas ◽  
Konstantin Rasiulis ◽  
Mečislovas Griškevičius ◽  
Tomas Gečys
Keyword(s):  
Bearing Capacity ◽  
Extreme Points ◽  
The European Union ◽  
Maintenance Period ◽  
Cylindrical Tank ◽  
Load Bearing Capacity ◽  
Complex Investigation ◽  
Load Bearing ◽  
Thin Walled Structures ◽  
Thin Walled

Design of modern thin-walled metal structures is widely used around the world. In recent decades, more comprehensive research is carried out to investigate the behaviour of various thin-walled structures. Generally, the structure with regular geometry is investigated. In various countries such as USA, Russia, and the European Union issued the standards on regulation of the construction, design and maintenance of thin-walled structures. The actually used period of tanks usually is longer than recommendatory period. Recommendatory maintenance period of metal tanks is 15–20 years. Therefore, for such structures one of the most considerable questions is the residual load bearing capacity beyond the end of the maintenance period. This phase of using of structures is associated with complex investigation and numerical analysis of thin-walled structures. In this paper the load bearing capacity of the steel wall of the existing over-ground vertical cylindrical tank in volume of 5,000 m3 with a single defect and with a few contiguous local defects of the shape is analyzed. Calculations carried out are taking into account all the imperfections of the wall geometry. A major goal of the research – developing a realistic numerical model of the object analyzed, taking into account all the imperfections, determining the wall stress and strain state, exploring the places of extreme points, calculating the residual load bearing capacity of the tank and scrutinizing possible strengthening schemes for defective areas.

Numerical Simulations of Filling Flows in Die-Casting Molding of the Thin-Walled LED Heat Sink

2014 ◽  
Author(s):  
Rong-Yuan Jou
Keyword(s):  
Computational Model ◽  
Numerical Simulations ◽  
Heat Sink ◽  
Die Casting ◽  
Mold Temperature ◽  
Geometrical Parameters ◽  
Vacuum Die Casting ◽  
Porosity Defects ◽  
Thin Walled ◽  
3D Software

In this study, the mold filling analyses of a thin-walled LED heat sink combined with the vacuum valve runner are simulated by FLOW-3D software. Two topics are analyzed and discussed. First, numerical simulations for variety of molding conditions, including effects of thermal conductivity, vacuum pumping pressure, mold temperature, filling velocity, respectively, are conducted for the computational model of the thin-walled LED heat sink connected with the vacuum shut-off valve. Second, effects of several geometrical parameters, including fin thicknesses of the LED heat sink and dimensions of the vacuum shut-off valve are explored. In these two topics, melts are set to liquid metal of Al 384.0 materials. The first topic of analysis mainly to investigate the effects of molding parameters based upon the same computational model of the thin-walled LED heat sink connected with a vacuum valve runner. The simulated results show if molding conditions are changed, different sizes of defects are appeared in castings; if vacuum pumping pressure is higher, the casting is also firmness, density prone to increase; if vacuum pumping pressure is too low, then pumping efficiency of mold cavity is low and it will be easy to form the casting porosity defects. For the second topic of analysis, molding conditions are hold constantly, and effects of different geometrical dimensions to castings qualifications are simulated. Characteristic dimension of trigger mechanism can effectively operate the vacuum shut-off function; but too thin or too thick of channel, it will affect the pumping time if different degrees of vacuum is imposed. Decreasing of gas residuals in castings for the vacuum pumping pressures of 760Torr, 200Torr, 100Torr compared with 10Torr, were 0.311%, 0.174%, 0.008%, respectively. It shows the appropriate and effective vacuum level for vacuum die-casting of the thin-walled LED heat sink is in the range of 100Torr.

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