scholarly journals Severity assessment of aircraft engine fan blades under airborne collision of unmanned aerial vehicles comparable to bird strike certification standards

2021 ◽  
pp. 095441002110449
Author(s):  
Mohd Hasrizam Che Man ◽  
Hu Liu ◽  
Kin Huat Low
Keyword(s):  
Kinetic Energy ◽  
Fem Simulation ◽  
Aircraft Engine ◽  
Bird Strike ◽  
Weight Category ◽  
Severity Level ◽  
Drone Strikes ◽  
Particle Hydrodynamics ◽  
The Difference ◽  
Potential Damage

Airborne drone collision on commercial manned aircraft has received extensive awareness due to the increasing drone operations in the restricted airspace. In addition, the bird strike certification for aircraft engines is likely to be inadequate for a drone collision with identical kinetic energy due to the difference in damage levels. Thus, it is important to understand and compare the risk between drones and bird strikes. This study aims to understand the damage severity from bird and drone strikes on the manned commercial aircraft engine. The finite element method (FEM) simulation is adopted to obtain the damage of engine fan blades under the drone collision and bird strikes at different collision positions. The Lagrangian and smoothed-particle hydrodynamics approaches are employed for the drone and bird simulations, respectively. In addition, three different drone and bird weight categories were considered in this study, namely, small, medium, and large, to investigate the effect of kinetic energy on the damage of fan blades. Results from the FEM simulation demonstrated that the damage of the engine fan blades due to drone collisions were more severe when comparing bird strikes of the same weight category. The damage severity level was proposed based on the damage of engine fan blades. In the event of a drone ingestion, the damage severity level assists in the identification of potential damage to engine fan blades and its performance.

scholarly journals The Role of Discs in the Collapse and Fragmentation of Prestellar Cores

2016 ◽  
Vol 33 ◽  
Author(s):  
O. Lomax ◽  
A. P. Whitworth ◽  
D. A. Hubber
Keyword(s):  
Kinetic Energy ◽  
Smoothed Particle Hydrodynamics ◽  
Low Mass Stars ◽  
Gravitational Instabilities ◽  
Disc Material ◽  
Prestellar Cores ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Low Mass

AbstractDisc fragmentation provides an important mechanism for producing low-mass stars in prestellar cores. Here, we describe smoothed particle hydrodynamics simulations which show how populations of prestellar cores evolve into stars. We find the observed masses and multiplicities of stars can be recovered under certain conditions.First, protostellar feedback from a star must be episodic. The continuous accretion of disc material on to a central protostar results in local temperatures which are too high for disc fragmentation. If, however, the accretion occurs in intense outbursts, separated by a downtime of ~ 104yr, gravitational instabilities can develop and the disc can fragment.Second, a significant amount of the cores’ internal kinetic energy should be in solenoidal turbulent modes. Cores with less than a third of their kinetic energy in solenoidal modes have insufficient angular momentum to form fragmenting discs. In the absence of discs, cores can fragment but results in a top-heavy distribution of masses with very few low-mass objects.

scholarly journals Simulation of Bullet Fragmentation and Penetration in Granular Media

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5243
Author(s):  
Froylan Alonso Soriano-Moranchel ◽  
Juan Manuel Sandoval-Pineda ◽  
Guadalupe Juliana Gutiérrez-Paredes ◽  
Usiel Sandino Silva-Rivera ◽  
Luis Armando Flores-Herrera
Keyword(s):  
Kinetic Energy ◽  
Granular Media ◽  
Elastic Collision ◽  
Smooth Particle Hydrodynamics ◽  
X Ray ◽  
Bullet Fragmentation ◽  
Particle Hydrodynamics ◽  
The Moment ◽  
Physical Phenomena ◽  
The Impact

The aim of this work is to simulate the fragmentation of bullets impacted through granular media, in this case, sand. In order to validate the simulation, a group of experiments were conducted with the sand contained in two different box prototypes. The walls of the first box were constructed with fiberglass and the second with plywood. The prototypes were subjected to the impact force of bullets fired 15 m away from the box. After the shots, X-ray photographs were taken to observe the penetration depth. Transient numerical analyses were conducted to simulate these physical phenomena by using the smooth particle hydrodynamics (SPH) module of ANSYS® 2019 AUTODYN software. Advantageously, this module considers the granular media as a group of uniform particles capable of transferring kinetic energy during the elastic collision component of an impact. The experimental results demonstrated a reduction in the maximum bullet kinetic energy of 2750 J to 100 J in 0.8 ms. The numerical results compared with the X-ray photographs showed similar results demonstrating the capability of sand to dissipate kinetic energy and the fragmentation of the bullet caused at the moment of impact.

scholarly journals Bird-Strike Resistance of Composite Laminates with Different Materials

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 129 ◽  
Author(s):  
Yadong Zhou ◽  
Youchao Sun ◽  
Tianlin Huang
Keyword(s):  
Composite Materials ◽  
Composite Laminates ◽  
Impact Damage ◽  
Dynamic Properties ◽  
Dynamic Structure ◽  
Strength Properties ◽  
Bird Strike ◽  
Particle Hydrodynamics ◽  
Bird Impact ◽  
The Impact

To obtain some basic laws for bird-strike resistance of composite materials in aeronautical application, the high-velocity impact behaviors of composite laminates with different materials were studied by numerical methods. The smoothed particle hydrodynamics (SPH) and finite element method (FEM) coupling models were validated from various perspectives, and the numerical results were comparatively investigated. Results show that the different composite materials have relatively little effect on projectile deformations during the bird impact. However, the impact-damage distributions can be significantly different for different composite materials. The strength parameters and fracture energy parameters play different roles in different damage modes. Lastly, modal frequency was tentatively used to explain the damage behavior of the composite laminates, for it can manifest the mass and stiffness characteristics of a dynamic structure. The dynamic properties and strength properties jointly determine the impact-damage resistance of composite laminates under bird strike. Future optimization study can be considered from these two aspects.

3D FEM Simulation of the Effect of Cooling Rate on SDAS and Macrosegregation of a High Strength Steel

2018 ◽  
Vol 941 ◽  
pp. 2360-2364 ◽  
Author(s):  
Gary Brionne ◽  
Abdelhalim Loucif ◽  
Chun Ping Zhang ◽  
Louis Philippe Lapierre-Boire ◽  
Mohammad Jahazi
Keyword(s):  
Boundary Conditions ◽  
Mushy Zone ◽  
Cooling Rate ◽  
High Strength Steel ◽  
Fem Simulation ◽  
High Strength ◽  
3D Fem ◽  
Cooling Rates ◽  
Positive Segregation ◽  
The Difference

Secondary dendrite arm spacing (SDAS) is a macrosegregation parameter directly linked to content of macrosegregation through cooling rates. The aim of this paper is to highlight the effect of cooling rate on the SDAS and macrosegregation patterns in a high strength steel. For this purpose, directionnal solidification in a cylinder was modeled with a plane-front solidification. Two cylinders were modeled with different boundary conditions (Tsurface = 1000°C and 1200°C). Using the FEM software Thercast, 3D macrosegregation maps were generated with thermomechanic algorithm taking into account metal shrinkage. Using Won’s equation, the influence of cooling rates in the mushy zone on SDAS was determined. The results indicated that a 72% lower difference in the area of negative macrosegregation zone (macrosegregation ratio (rseg) < -0.016%) for lower cooling rate (Ts = 1200°C). The difference of the area for positive segregation was 85% lower for higher cooling rates.

Soft Magnetism and Morphology of Fe Films by Dual Ion Beam Sputtering

1988 ◽  
Vol 128 ◽  
Author(s):  
M. Nagakubo ◽  
T. Yamamoto ◽  
M. Naoe
Keyword(s):  
Kinetic Energy ◽  
Ion Beam ◽  
Film Surface ◽  
Columnar Structure ◽  
Ion Beam Sputtering ◽  
Beam Sputtering ◽  
Argon Ions ◽  
The Difference ◽  
Dual Ion Beam Sputtering ◽  
Soft Magnetism

ABSTRACTFe films have been deposited by using dual ion beam sputtering apparatus under various conditions, and the dependence of their magnetic properties and morphology on preparation parameters such as film thickness, δt, and argon gas pressure, PAr, have been investigated in detail. The saturation magnetiza ion 4πMs of the specimen films did not change remarkably with 6t in the range of 50 ∼1000nm. However, with decrease of 6t below 50 nm, 4πMs decreased to less than 20 kG and coercivity Hc increased to more than 16 Oe. As PAr increased from 0.5 to 1.6 mTorr without ion bombardment, 4πMs decreased to less than 20 kG and Hc increased to about 20 Oe. The SEM micrographs of these films deposited at higher PAr showed the columnar structure. On the other hand, the films deposited at Yower PAr and ones bombarded by argon ions with proper kinetic energy during deposition did not present any texture and exhibited better soft magnetism. Such a morphology may be attributed to the difference in arrival energy of sputtered Fe particles to film surface and related closely to soft magnetism. It has been found that the dual ion beam sputtering method can control 4πMs and Hc with changing PAr and so prepare Fe films with superior soft magnetism by adjusting the kinetic energy of bombarding argon ions at lower PAr.

scholarly journals Determining the solar structure from oscillation frequencies

1995 ◽  
Vol 10 ◽  
pp. 329-331
Author(s):  
S. Basu
Keyword(s):  
Inverse Problem ◽  
Kinetic Energy ◽  
Unknown Function ◽  
Sound Speed ◽  
Reference Model ◽  
Solar Interior ◽  
Model Parameters ◽  
Surface Layers ◽  
The Difference ◽  
Oscillation Frequencies

The inverse problem of finding the structure of the solar interior from the observed frequencies can be written aswhere, δωi is the difference in frequency of the ith mode between the solar data and the reference model, f1 and f2 are an appropriate pair of model parameters (e.g. sound speed squared c2, and density ρ), Ei is the mode kinetic energy, K(1) and K(2) are known functions of the reference model, and F(ω) is the unknown function added to account for uncertainties associated with the physics of the surface layers.

Experimental Investigation of Unsteady Flow Field Within a Two Stage Axial Turbomachine Using Particle Image Velocimetry

2002 ◽  
Author(s):  
Oguz Uzol ◽  
Yi-Chih Chow ◽  
Joseph Katz ◽  
Charles Meneveau
Keyword(s):  
Particle Image Velocimetry ◽  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Particle Image ◽  
Energy Levels ◽  
Shear Stresses ◽  
Image Velocimetry ◽  
Entire Flow ◽  
The Difference

Detailed measurements of the flow field within the entire 2nd stage of a two stage axial turbomachine are performed using Particle Image Velocimetry. The experiments are performed in a facility that allows unobstructed view on the entire flow field, facilitated using transparent rotor and stator and a fluid that has the same optical index of refraction as the blades. The entire flow field is composed of a “lattice of wakes”, and the resulting wake-wake and wake-blade interactions cause major flow and turbulence non-uniformities. The paper presents data on the phase averaged velocity and turbulent kinetic energy distributions, as well as the average-passage velocity and deterministic stresses. The phase-dependent turbulence parameters are determined from the difference between instantaneous and the phase-averaged data. The distributions of average-passage flow field over the entire stage in both the stator and rotor frames of reference are calculated by averaging the phase-averaged data. The deterministic stresses are calculated from the difference between the phase-averaged and average-passage velocity distributions. Clearly, wake-wake and wake-blade interactions are the dominant contributors to generation of high deterministic stresses and tangential non-uniformities, in the rotor-stator gap, near the blades and in the wakes behind them. The turbulent kinetic energy levels are generally higher than the deterministic kinetic energy levels, whereas the shear stress levels are comparable, both in the rotor and stator frames of references. At certain locations the deterministic shear stresses are substantially higher than the turbulent shear stresses, such as close to the stator blade in the rotor frame of reference. The non-uniformities in the lateral velocity component due to the interaction of the rotor blade with the 1st stage rotor-stator wakes, result in 13% variations in the specific work input of the rotor. Thus, in spite of the relatively large blade row spacings in the present turbomachine, the non-uniformities in flow structure have significant effects on the overall performance of the system.

Parametric Bird Strike Study of a Transonic Rotor Using Isogeometric Analysis

2016 ◽  
Author(s):  
Sam Duckitt ◽  
Chiara Bisagni ◽  
Shahrokh Shahpar
Keyword(s):  
Isogeometric Analysis ◽  
Control Points ◽  
Bird Strike ◽  
Transonic Compressor ◽  
Mechanical Constraints ◽  
Compressor Rotor ◽  
Centrifugal Load ◽  
Design Variables ◽  
Particle Hydrodynamics ◽  
The Impact

This paper investigates the use of isogeometric analysis (IGA) to study high velocity impact on a transonic compressor rotor resulting from a bird strike. An approach is developed for creating volumetric NURBS blade models which are suitable for IGA. A newly implemented 3D solid NURBS element within the development version of LS-Dyna is validated against finite elements for the NASA rotor 37 under a steady centrifugal load. The smoothed particle hydrodynamics (SPH) method is then used to simulate impact from a bird strike. As a preliminary assessment for multi-disciplinary optimisation (MDO), with the objective to improve aerodynamic performance whilst satisfying mechanical constraints from impact, a number of different blade designs are created by modifying the NURBS control points directly. Hence the control points used in analysis can also be used in the design space. This approach eliminates the need for re-meshing, highlighting the advantages that IGA can bring to design optimisation, since without filtering, moving finite element nodes can result in non-smooth geometries. NURBS parametrisations are also more efficient resulting in fewer design variables, thereby accelerating the optimisation process. The effect of blade sweep, lean, twist and thickness on the impact response are investigated. The results in this paper show the promise that IGA holds in this field but some limitations of the current LS-Dyna implementation are also discussed.

scholarly journals Correction of the Koenig Formula for the Kinetic Energy of a Rotating Solid

2021 ◽  
Author(s):  
Yuriy Alyushin
Keyword(s):  
Kinetic Energy ◽  
Superposition Principle ◽  
The Body ◽  
Initial State ◽  
Moments Of Inertia ◽  
Lagrange Form ◽  
Joint Plane ◽  
Angular Velocities ◽  
The Difference ◽  
Cyclic Changes

An exact solution is obtained for the kinetic energy in the general case of the spatial motion of solids with arbitrary rotation, which differs from the Koenig formula by three additional terms with centrifugal moments of inertia. The description of motion in the Lagrange form and the superposition principle are used, which provides a geometric summation of the velocities and accelerations of the joint motions in the Lagrange form for any particle at any time. The integrand function in the equation for kinetic energy is represented by the sum of the identical velocity components of the joint plane-parallel motions. The moments of inertia in the Koenig formula do not change during movement and can be calculated from the current or initial state of the body. The centrifugal moments change and turn to 0 when rotating relative to the main central axes only for bodies with equal main moments of inertia, for example, for a ball. In other cases, the difference in the main moments of inertia leads to cyclic changes in the kinetic energy with the possible manifestation of precession and nutation, the amplitude of which depends on the angular velocities of rotation of the body. An example of using equations for a robot with one helical and two rotational kinematic pairs is given.

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