Sensitivity Study of Boundary Conditions for a 9-Meter Drop of a Shielded Cask for Operational Handling of a Container of Liquid

2016 ◽  
Author(s):  
Michael C. Yaksh ◽  
Suresh Babu
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Boundary Conditions ◽  
Pressure Vessel ◽  
Element Model ◽  
Computer Code ◽  
Sensitivity Study ◽  
Confined Space ◽  
Explicit Finite Element ◽  
The Impact

A shielded cask is used to move welded containers whose contents are liquid. The requirement controlling the design of the shielded cask was the 9-meter drop. Since the orientation of the cask is arbitrary, it is required to assume an orientation which would result in the most damage to the cask. For such drops the target is usually considered to be an unyielding surface. The shielded cask of interest is not designed with components to mitigate the damage due to such drops. The shielded cask contains a thick shell of lead which is considered to move and deform during the 9-meter drop. Additionally, the container of liquid is not physically attached to the cask, and is free to move within the confined space during the event as well. Each component has its own unique stiffness and mass characteristics which could result in a different dynamic response. Since the dynamic response of each component is different, the most damage to a particular component may be sensitive to the boundary conditions. The unyielding surface would maximize the damage to the impact surface of the cask, but as a result, could mitigate the maximum loading applied to other components of the cask. Most actual targets are comprised of concrete. The evaluations are performed using an explicit finite element computer code. Consequently, it is necessary to monitor certain energies, such as the hourglass energy or a sliding energy indicating the behavior of the contact surface associated with the target. These parameters confirm the accurate behavior of the elements comprising the finite element model. Given that components can have a different response, the hourglass energy may also vary. Varying the boundary conditions will affect these types of parameters. In this paper, the authors present the results of a study of the effect of the boundary conditions on the shielded cask components response to the 9-meter drop. The primary orientation of interest is the end drop. The end drop maximizes the axial loading to the container. It is this orientation which could result in the most compression of the lead shield leading to increased radiation exposure. The container is considered as a pressure vessel and its integrity would be evaluated using the plastic strain based criteria contained in Section III, Division 3. The shielded cask, however, is not a pressure vessel and was evaluated using Section VIII, Division 2, Part 5. Both evaluations used the plastic strains and triaxiality factors determined from the drop evaluations.

Numerical and Experimental Investigation on the Energy Absorption Capability of a Full-Scale Composite Fuselage Section

2019 ◽  
Vol 827 ◽  
pp. 19-24 ◽  
Author(s):  
Donato Perfetto ◽  
Giuseppe Lamanna ◽  
M. Manzo ◽  
A. Chiariello ◽  
F. di Caprio ◽  
...  
Keyword(s):  
Finite Element ◽  
Energy Absorption ◽  
Load Condition ◽  
Element Model ◽  
Full Scale ◽  
Research Centre ◽  
Fe Method ◽  
Explicit Finite Element ◽  
Crashworthiness Design ◽  
The Impact

In the case of catastrophic events, such as an emergency landing, the fuselage structure is demanded to absorb most of the impact energy preserving, at the same time, a survivable space for the passengers. Moreover, the increasing trend of using composites in the aerospace field is pushing the investigation on the passive safety capabilities of such structures in order to get compliance with regulations and crashworthiness requirements. This paper deals with the development of a numerical model, based on the explicit finite element (FE) method, aimed to investigate the energy absorption capability of a full-scale 95% composite made fuselage section of a civil aircraft. A vertical drop test, performed at the Italian Aerospace Research Centre (CIRA), carried out from a height of 14 feet so to achieve a ground contact velocity of 30 feet/s in according to the FAR/CS 25, has been used to assess the prediction capabilities of the developed FE method, allowing verifying the response under dynamic load condition and the energy absorption capabilities of the designed structure. An established finite element model could be used to define the reliable crashworthiness design strategy to improve the survival chance of the passengers in events such as the investigated one.

Nonlinear FEA Simulation of Thorax Dynamic Response Under Blast Load

2012 ◽  
Author(s):  
Yahia M. Al-Smadi ◽  
Nedal Sumrein ◽  
Omar Awad ◽  
Oruba Rabie
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Element Model ◽  
Severe Injuries ◽  
Element Analysis ◽  
Explicit Finite Element ◽  
Blast Overpressure ◽  
Explicit Finite Element Analysis ◽  
New Material ◽  
Fea Simulation

Blast overpressure can cause severe injuries of several organs ranging from local injury to collapse or rapture of vital organs rapidly and death. This paper will investigate the thorax dynamic response for blast loading. The presented numerical blast tests will accompany the introduction of new material modeling details. Reliable and robust analysis explicit finite element analysis software (ANSYS and LS-DYNA) will be used to complete 3D finite element model and conduct numerical testing.

Parameter characterization of a buried mine blast event with further emphasis on sympathetic detonation and layered soil bed conditions

2021 ◽  
pp. 154851292110211
Author(s):  
Morten Rikard Jensen ◽  
Wilford Smith ◽  
Kshitiz Khanna
Keyword(s):  
Finite Element ◽  
Natural Extension ◽  
Structural Response ◽  
Particle Method ◽  
Element Model ◽  
Sensitivity Study ◽  
Layered Soil ◽  
Explicit Finite Element ◽  
Response Parameter ◽  
Size Type

The presented work documents the results of a comprehensive sensitivity study of the structural response of a military vehicle subjected to the impulse from a buried charge using the discrete particle method (DPM) to model the soil and high explosive (HE) coupled to a finite-element solver for the structure. Eighteen different process and numerical parameters were studied. Each of the numerical results was compared with a base model to see the influence of the considered parameter. The structure in the base model was the TARDEC Generic Vehicle Hull and the response parameter was chosen to be the total blast impulse (TBI) on the structure. The non-linear transient dynamic explicit finite-element solver used for the analysis was the IMPETUS Afea Solver®. The study includes soil characteristics and charge related parameters, such as size, type, geometry, and location. The depth of burial (DOB) and number of discrete particles were also considered in the study. Further, different numerical parameters were included. The results provide a good understanding of process and numerical parameters when modeling buried charges with a coupled finite-element model (FEM) and DPM approach. As a natural extension of the sensitivity study the effect of a layered soil bed is investigated, the topsoil either being dry or wet soil. Further, it is illustrated how to model a sympathetic detonation where the detonation of one improvised explosive device (IED) generates a pressure that results in the detonation of a second IED.

Simplified explicit finite element model for the impact of a wheel on a crossing – Validation and parameter study

2017 ◽  
Vol 111 ◽  
pp. 254-264 ◽  
Author(s):  
Julian Wiedorn ◽  
Werner Daves ◽  
Uwe Ossberger ◽  
Heinz Ossberger ◽  
Martin Pletz
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Parameter Study ◽  
Explicit Finite Element ◽  
The Impact

Finite Element Modelling of a Generic Rotor-Bearing System and Experimental Validation

2015 ◽  
Author(s):  
A. Rehman ◽  
K. S. Ahmed ◽  
F. A. Umrani ◽  
B. Munir ◽  
A. Mehboob ◽  
...  
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Finite Element Model ◽  
Element Model ◽  
Mode Shapes ◽  
Efficient Operation ◽  
Critical Speeds ◽  
Rotor Bearing ◽  
The Impact ◽  
Bearing System

The design and development of the rotating machinery require a precise identification of its dynamic response for efficient operation and failure prevention. Determination of critical speeds and mode shapes is crucial in this regard. In this paper, a finite element model (FEM) based on the Euler beam theory is developed for investigating the dynamic behavior of flexible rotors. In-house code in Scilab environment, an open source platform, is developed to solve the matrix equation of motion of the rotor-bearing system. The finite element model is validated by the impact hammer test and the dynamic testing performed on the rotors supported on a purpose-built experimental setup. Bearing stiffness is approximated by using the Hertzian contact theory. Obtaining the critical speeds and mode shapes further improves the understanding of dynamic response of rotors. This study paves way towards advanced research in rotordynamics in Faculty of Mechanical Engineering, GIK Institute.

Agricultural aircraft wing slat tolerance for bird strike

2017 ◽  
Vol 89 (4) ◽  
pp. 590-598 ◽  
Author(s):  
Adam Deskiewicz ◽  
Rafał Perz
Keyword(s):  
Finite Element ◽  
Impact Velocity ◽  
Structural Response ◽  
Element Model ◽  
Bird Strike ◽  
Element Analysis ◽  
Content Type ◽  
Explicit Finite Element ◽  
Explicit Finite Element Analysis ◽  
The Impact

Purpose The aim of this study is to assess and describe possible consequences of a bird strike on a Polish-designed PZL-106 Kruk agricultural aircraft. Due to its susceptibility to such events, a wing slat has been chosen for analysis. Design/methodology/approach Smooth particle hydrodynamics (SPH) formulation has been used for generation of the bird finite element model. The simulations were performed by the LS-Dyna explicit finite element analysis software. Several test cases have been analysed with differing parameters such as impact velocity, initial velocity vector direction, place of impact and bird mass. Findings Results of this study reveal that the structure remains safe after an impact at the velocity of 25 m/s. The influence of bird mass on slat damage is clearly observable when the impact velocity rises to 60 m/s. Another important finding was that in each case where the part did not withstand the applied load, it was the lug where first failure occurred. Some of the analysed cases indicated the possibility a consequent wing box damage. Practical implications This finding provides the manufacturer an important insight into the behaviour of the slat and suggests that more detailed analysis of the current lug design might improve the safety of the structure. Originality/value Even though similar analyses have been performed, they tended to focus on large transport aircraft components. This investigation will enhance our understanding of structural response of small, low-speed aircraft to a bird impact, which is a realistic scenario for the chosen case of an agricultural plane.

A numerical investigation of the influence of yarn-level finite-element model on energy absorption by a flexible-fabric armour during ballistic impact

2008 ◽  
Vol 222 (4) ◽  
pp. 259-276 ◽  
Author(s):  
M Grujicic ◽  
G Arakere ◽  
T He ◽  
M Gogulapati ◽  
B A Cheeseman
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Three Dimensional ◽  
Element Model ◽  
Far Field ◽  
Field Boundary ◽  
Fem Model ◽  
Energy Absorbing ◽  
The Impact ◽  
Textile Fabric

A series of transient non-linear dynamic finite-element method (FEM) analyses pertaining to the interaction of a single-ply plain-woven balanced square textile-fabric armour with a spherical steel projectile is carried out in order to compare the corresponding results obtained for two different yarn models: (a) a solid FEM model in which the warp and weft yarns are represented using first-order three-dimensional solid elements and (b) a membrane model in which the same yarns are represented using second-order membrane elements. The analyses are carried out under different yarn—yarn and projectile—fabric frictional conditions and under different far-field boundary conditions applied to the edges of the fabric. The results obtained showed that the two sets of analyses yield comparable predictions regarding the temporal evolution and the spatial distribution of the deformation and damage fields within the fabric, regarding the ability of the fabric to absorb the projectile's kinetic energy and regarding the relative contributions of the main energy absorbing mechanisms. The work also confirmed the roles yarn—yarn and projectile—fabric friction play in the impact process as well as the effect of the far-field boundary conditions applied to the edges of the fabric.

DYNAMIC RESPONSE OF PELVIC COMPLEX FINITE ELEMENT STUDY AND VALIDATION UNDER SIDE IMPACT

2017 ◽  
Vol 17 (07) ◽  
pp. 1740036 ◽  
Author(s):  
AILI QU ◽  
DONGMEI WANG ◽  
XIANGSEN ZENG ◽  
QIU’GEN WANG
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Impact Force ◽  
Pelvic Ring ◽  
Element Model ◽  
Hemodynamic Instability ◽  
Complex Model ◽  
Side Impact ◽  
Lateral Impact ◽  
The Impact

Objective: To investigate and validate dynamic response of the pelvis, a finite element model of seated pelvic complex comprising of bone, ligaments, abdominal artery and soft tissue was developed and concurrently, a cadaver experiment was set up. Materials and Methods: Based on supine scanned CT images, we first developed an FE pelvic complex model and modified it to construct a seated pelvic model by anteriorly rotating the proximal femur to 90[Formula: see text]. For the cadaver experiment, a customized pelvic impact apparatus was designed and optical devices, strain gauges and pressure detectors were used to measure the pelvic response. Results: The results of the FE analysis and the cadaver tests were congruent in terms of impact force and fracture sites. Dynamic arterial response to the lateral impact showed hemodynamic instability that was displayed in pressure variation. The response of ligaments indicated that the posterior ligaments of pelvic ring experienced a larger amount of load. Conclusion: FE results provided the impact of ligaments and arteries besides impact force, compression (C) and viscous criterion (VC). Accordingly, the cadaver experiment measured arterial pressure, impact force, bone strain and compression. The compatibility between the FE and cadaver analyses demonstrates the high bio-fidelity of our pelvic complex model.

scholarly journals Stiffness Estimation and Equivalence of Boundary Conditions in FEM Models

2021 ◽  
Vol 11 (4) ◽  
pp. 1482
Author(s):  
Róbert Huňady ◽  
Pavol Lengvarský ◽  
Peter Pavelka ◽  
Adam Kaľavský ◽  
Jakub Mlotek
Keyword(s):  
Boundary Condition ◽  
Finite Element ◽  
Boundary Conditions ◽  
Model Updating ◽  
Element Model ◽  
Computational Time ◽  
Stiffness Coefficients ◽  
First Case ◽  
Numerical Approaches

The paper deals with methods of equivalence of boundary conditions in finite element models that are based on finite element model updating technique. The proposed methods are based on the determination of the stiffness parameters in the section plate or region, where the boundary condition or the removed part of the model is replaced by the bushing connector. Two methods for determining its elastic properties are described. In the first case, the stiffness coefficients are determined by a series of static finite element analyses that are used to obtain the response of the removed part to the six basic types of loads. The second method is a combination of experimental and numerical approaches. The natural frequencies obtained by the measurement are used in finite element (FE) optimization, in which the response of the model is tuned by changing the stiffness coefficients of the bushing. Both methods provide a good estimate of the stiffness at the region where the model is replaced by an equivalent boundary condition. This increases the accuracy of the numerical model and also saves computational time and capacity due to element reduction.

Geometrically nonlinear static and dynamic analysis of CNT reinforced laminated composite plates: A finite element study

2021 ◽  
pp. 095440622110089
Author(s):  
Balakrishna Adhikari ◽  
BN Singh
Keyword(s):  
Finite Element ◽  
Free Vibration ◽  
Dynamic Response ◽  
Integration Scheme ◽  
Static And Dynamic Analysis ◽  
Finite Element Study ◽  
Nonlinear Eigenvalues ◽  
Nonlinear Static ◽  
The Impact ◽  
Element Study

In this paper, a finite element study is conducted using the Green Lagrange strain field based on vonKarman assumptions for the geometric nonlinear static and dynamic response of the laminated functionally graded CNT reinforced (FG-CNTRC) composite plate. The governing equations for determining the nonlinear static and dynamic behavior of the FG-CNTRC plate are derived using the Lagrange equation of motion based on Reddy's higher order theory. Using the direct iteration technique, the nonlinear eigenvalues for analyzing the free vibration response are obtained and the nonlinear dynamic responses of the FG-CNTRC plate are encapsulated based on the nonlinear Newmark integration scheme. The impact of the amplitude of vibration on mode switching phenomena and the consequence of the duration of the pulse on the free vibration regime of the plate are outlined. Also, the effect of time dependent loads is studied on the normal stresses of the plate. Furthermore, the impact on the nonlinear static and dynamic response of the laminated FG-CNTRC plate of various parameters such as span-thickness ratio (b/h ratio), aspect ratio (a/b ratio), different edge constraints, CNT fiber gradation, etc. are also studied.

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