DEVELOPMENT OF A FRANGIBLE DESIGN OF SMALL FIXED-WING UNMANNED AERIAL SYSTEM

2021 ◽  
Author(s):  
ANURAG ◽  
KALYAN RAJ KOTA ◽  
THOMAS E. LACY
Keyword(s):  
Unmanned Aircraft ◽  
Fe Model ◽  
Initial Stage ◽  
Internal Structures ◽  
Significant Damage ◽  
Target Frame ◽  
Energy Absorbing ◽  
Impact Simulations ◽  
The Impact ◽  
Collision Trajectory

Existing studies show that small fixed-wing unmanned aircraft systems’ (FWUASs) mid-air collisions with aircraft can cause substantial damage. Upon a 250 knots impact, a ~1.8 kg “tractor” configuration of FW-UAS can perforate aircraft skin, thereby damaging the internal structures such as ribs, frames, etc., posing severe threat to manned air fleet. Significant damage is primarily caused by FW-UAS’s heavy and rigid components such as motor, battery, and payload especially due to their roughly in-line arrangement and proximity with one another. In this work, a modified FW-UAS finite element (FE) model was developed that included a “pusher” engine (i.e., motor in the aft of the forward fuselage) configuration to reduce the impact severity during airborne collisions. A polymeric foam nosecone was attached to the front of the FW-UAS FE model to dissipate impact energy. To assess its energy absorbing capacity, a comparative study with expanded polypropylene (EPP), polyurethane (PUR), and polystyrene (IMPAXX700) foams was performed. Conical and semi-spherical nosecone configurations were studied as part of this research. A series of LS-Dyna impact simulations were performed with the pusher configuration of FW-UAS impacting a 1.59 mm thick aluminum 2024-T3 flat plate sandwiched between a rigid target frame. In addition, a frangible design of the FW-UAS, in which the payload is diverged from the in-line collision trajectory of battery and motor upon impact, was implemented and assessed. Force generated during the initial stage of impact is leveraged through lightweight and friable structural links to diverge the payload to avoid impact along the single axis as of the battery and motor. Damage severity is evaluated through target plate tear, and velocity of payload during impact, it being the major damage causing component.

Further Validation of the Ford Human Body FE Model and Use of the Model to Investigate the Effects of Shoulder Belt Force Limiting of 3-Point and 4-Point Restraints in Frontal Impact

2008 ◽  
Author(s):  
Raed E. El-Jawahri ◽  
Jesse S. Ruan ◽  
Stephen W. Rouhana ◽  
Saeed D. Barbat ◽  
Priya Prasad
Keyword(s):  
Human Body ◽  
Ford Motor Company ◽  
Steering Wheel ◽  
Point System ◽  
Fe Model ◽  
Frontal Impact ◽  
Frontal Impacts ◽  
Vehicle Structure ◽  
Impact Simulations ◽  
The Impact

Ford Motor Company human body FE model was validated against 3-point & 4-point belted PMHS tests in frontal impact and PMHS knee impact. The chest deflection, chest acceleration, and belt force in frontal impact simulations were compared with the PMHS test data, while the impact force, femur acceleration, pelvis acceleration, and sacrum acceleration of the knee impact simulations were compared with the respective corridors from PMHS tests. The model used represents a 50th percentile adult male. It was used to study the effects of shoulder belt force limit on 3-point and 4-point restrained occupants in frontal impacts without airbags. A 25 g pulse and a shoulder belt load limit of 1, 2, 3, 4, 6, and 8 kN were used for the 3-point and 4-point restraint systems with a rigid steering wheel, front header, and windshield of a stiffer larger vehicle structure. The results showed that the head acceleration and the chest deflection of the 4-point belt system are less than the respective cases of the 3-point system while the chest acceleration levels were about the same in 3-point and 4-point belt. The mid-shaft femur forces were always higher in the 4-point belt than those of the 3-point belt.

Influence of the Cross Section Shape on Energy Absorbing Component of Bumper Subjected to Low Speed Crash

2013 ◽  
Vol 477-478 ◽  
pp. 3-6
Author(s):  
Yan Jie Liu ◽  
Lin Ding
Keyword(s):  
Energy Absorption ◽  
Cross Section ◽  
Peak Load ◽  
Low Velocity Impact ◽  
Fe Model ◽  
Cross Section Shape ◽  
Section Shape ◽  
The Cross ◽  
Energy Absorbing ◽  
The Impact

Energy absorbing component of bumper equipped at the front end of a car, is one of the most important automotive parts for crash energy absorption. It usually was made a mental thin walled tube. In the paper, automobile energy absorbing component at low-velocity impact was studied by using Finite Element Method. The FE model of the tube was builded by comparing the five cross section shape . Results show that the impact peak load and maximum energy absorption have certain effect to energy-absorbing component with different the cross section shape.

scholarly journals Crashworthiness Characteristics of Multi-Cell Tubular Structures Subjected to Axial Impact

2019 ◽  
Vol 8 (4) ◽  
pp. 3911-3915 ◽  
Keyword(s):  
Impact Energy ◽  
Deformation Behaviour ◽  
Initial Period ◽  
Geometrical Parameters ◽  
Tubular Structures ◽  
Axial Impact ◽  
Thin Walled ◽  
Energy Absorbing ◽  
Impact Simulations ◽  
The Impact

To mitigate the impact forces in crash events, thin-walled tubular elements are employed as an energy absorbing attenuators in frontal part of the automotive vehicles. To develop more progressive deformation modes, at the initial period, and to absorb more impact energy at the final period of crash, it is significant to enhance the crashworthiness performance of the tube by modifying its geometrical parameters. Multi-cell tubular structures have recognized to own superior impact energy absorbing ability and lightweight effect in the modern automotive vehicles. This research article examines the deformation behaviour of thin walled aluminum alloy multi-cell tube with different stiffeners exposed to axial impact loading using numerical simulation. Nonlinear impact simulations were performed on multi-cell tubes using finite element ABAQUS/CAE explicit code. From the overall results obtained, the deformation behaviour of multi-cell tubes was compared. Furthermore, hexagonal tubes with stiffeners were retained as most prominent for better energy dissipation. This type of tube was found to be most efficient type to enhance the crashworthiness performance during axial impact.

Numerical Simulation and Structural Improvement for the Crashworthiness Capacity of M1 Type Commercial Vehicle

2016 ◽  
Author(s):  
Tao Wang ◽  
Liangmo Wang
Keyword(s):  
Commercial Vehicle ◽  
Fe Model ◽  
Impact Simulation ◽  
Structural Improvement ◽  
Physical Impact ◽  
Energy Absorbing ◽  
Deformation Area ◽  
The Impact ◽  
Huge Challenge ◽  
M1 Type

To investigate the crashworthiness capacity of a M1 type commercial vehicle, the full-scale finite element (FE) model of the vehicle has been established. On the basis of the FE model, the impact simulation subject to the 100% frontal impact has been carried out, and the results have been verified with the physical impact test. The analysis of the deformation path and the energy absorption indicates that the M1 vehicle lacks sufficient frontal deformation area and its peak crash acceleration (PCA) is too high, which raises a huge challenge for the sequent development of a safety restraint system. To enhance the crashworthiness of the M1 vehicle, some structural improvements have been implemented, with adding the energy absorbing box, improving the frontal frame parts and enhancing the front door. The frontal collapsing area has been investigated in order to figure out the layout position of the energy absorbing box. The design of the aluminum foam reinforced energy absorbing box has been made by using the surrogate modeling technique. The impact simulation results of the improved M1 vehicle show a significant decrease of the PCA and a more homogeneous energy absorbing status, which verifies the validity of the proposed structures for crashworthiness improvement.

Pedestrian Collision Responses Using Legform Impactor Subsystem and Full-Sized Pedestrian Model on Different Workbenches

2018 ◽  
Author(s):  
Obaidur Rahman Mohammed ◽  
Shabbir Memon ◽  
Hamid M. Lankarani
Keyword(s):  
Fe Model ◽  
Finite Model ◽  
Lower Extremity Injuries ◽  
Full Size ◽  
Pedestrian Impact ◽  
Extremity Injuries ◽  
Multi Body ◽  
Impact Simulations ◽  
The Impact ◽  
Pedestrian Collisions

Car-pedestrian collision fatalities have been reported for a significant number of roadside accidents around the world. In order to reduce the lower extremity injuries in car-pedestrian collisions, it is important to determine the impact forces on the pedestrian and conditions that the car frontal side impacts on the lower extremities of the pedestrian. The Working Group 17 (WG17) of the European Enhanced Vehicle-safety Committee (EEVC) has developed a legform subsystem impactor and procedure for assessing pedestrian collisions and potential injuries. This research describes a methodology for the evaluation of the legform impactor kinematics after a collision utilizing finite element (FE) models of the legform and cars and comparing the simulation results with the ones from a multi-body legform model as well as a 50th percentile male human pedestrian model responses. Two approaches are carried out in the process. First, the collision strike simulations with the FE model using an FE lower legform is considered and validated against the EVVC/WG17 regulation criteria. Secondly, the collision strike simulations with a multi-body legform and an ellipsoidal multi-body car model are conducted to compare the responses from the FE model and the multi-body model. The results from the impact simulations of FE legform and the multi-body legform are also compared with the ones from a full-size pedestrian model at constant speeds. All the models and simulation in this are using the LS-DYNA nonlinear FE code, while the multibody legform, car, and full-sized pedestrian models are developed and evaluated in MADYMO. The results from this study demonstrate the differences between the subsystem legform and the full-size pedestrian responses as well as suitability of various FE and multibody models related to pedestrian impact responses. Different workbenches comparisons with finite model and ellipsoidal models gives more better correlation to this research.

The Impact of Insect Infestation on Stored Purpled Cocoa Beans

2018 ◽  
Vol 1 (3) ◽  
pp. 176-181 ◽  
Author(s):  
E. Tettey
Keyword(s):  
Weight Loss ◽  
Insect Population ◽  
Insect Infestation ◽  
Percentage Weight Loss ◽  
Cocoa Beans ◽  
Significant Damage ◽  
Percentage Weight ◽  
Fermentation Period ◽  
The Impact

Under-fermentation of cocoa beans produces purple beans. The fermentation period is 6 to 7 days but some cocoa farmersunder-ferment their cocoa beans leading to the development of purple cocoa beans. This study determined the impact of insectinfestation on stored purple cocoa beans. Wet cocoa beans were fermented for 1, 2, 3, 4 and 5 days to produce the purple beans.Ephestia cautella and Tribolium castaneum, both singly and in combination, were introduced into the cocoa beans and storedfor different (30, 60, 90 and 120 days) period. Insect population, percentage weight loss and the contaminants produced bythese insects were determined. Cocoa beans infested with E. cautella alone had the highest population of 297.0 ± 22.7. Beansfermented for 3 days had the lowest insect population both singly and in combination after 120 days of storage. The highestpercentage weight loss was recorded in cocoa beans fermented for one day (10.1 ± 1.87%) and 4 days (10.1 ± 8.74%). T.castaneum did not cause much damage to the cocoa beans but E. cautella alone caused significant damage to stored cocoabeans. Insect infestation and poor fermentation contribute significantly to the reduction in quality of cocoa beans.

Impact of UAS with Low Size, Weight, and Power Sensors on Air Traffic Controllers’ Performance and Acceptability Ratings

2020 ◽  
Vol 64 (1) ◽  
pp. 154-158
Author(s):  
Kim-Phuong L. Vu ◽  
Jonathan VanLuven ◽  
Timothy Diep ◽  
Vernol Battiste ◽  
Summer Brandt ◽  
...  
Keyword(s):  
Air Traffic ◽  
Unmanned Aircraft ◽  
Unmanned Aircraft Systems ◽  
Subjective Ratings ◽  
Detection Range ◽  
Human In The Loop ◽  
Air Traffic Controllers ◽  
Low Altitude ◽  
Sector Performance ◽  
The Impact

A human-in-the-loop simulation was conducted to evaluate the impact of Unmanned Aircraft Systems (UAS) with low size, weight, and power (SWaP) sensors operating in a busy, low-altitude sector. Use of low SWaP sensors allow for UAS to perform detect-and-avoid (DAA) maneuvers against non-transponding traffic in the sector. Depending upon the detection range of the low SWaP sensor, the UAS pilot may or may not have time to coordinate with air traffic controllers (ATCos) prior to performing the DAA maneuver. ATCo’s sector performance and subjective ratings of acceptability were obtained in four conditions that varied in UAS-ATCo coordination (all or none) prior to the DAA maneuver and workload (higher or lower). For performance, ATCos committed more losses of separation in high than low workload conditions. They also had to make more flight plan changes to manage the UAS when the UAS pilot did not coordinate DAA maneuvers compared to when they did coordinate the maneuvers prior to execution. Although the ATCos found the DAA procedures used by the UAS in the study to be acceptable, most preferred the UAS pilot to coordinate their DAA maneuvers with ATCos prior to executing them.

scholarly journals Monitoring of the Impact of Lithium Nitrate on the Alkali–aggregate Reaction Using Acoustic Emission Methods

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 20
Author(s):  
Justyna Zapała-Sławeta ◽  
Grzegorz Świt
Keyword(s):  
Acoustic Emission ◽  
Initial Reaction ◽  
Lithium Nitrate ◽  
Acoustic Emission Method ◽  
Emission Method ◽  
Acoustic Activity ◽  
Initial Stage ◽  
Chemical Admixture ◽  
Different Characteristics ◽  
The Impact

The study analyzed the possibility of using the acoustic emission method to analyse the reaction of alkali with aggregate in the presence of lithium nitrate. Lithium nitrate is a chemical admixture used to reduce adverse effects of corrosion. The tests were carried out using mortars with reactive opal aggregate, stored under the conditions defined by ASTM C227. The acoustic activity of mortars with a corrosion inhibitor was referred to linear changes and microstructure of specimens in the initial reaction stages. The study found a low acoustic activity of mortars with lithium nitrate. Analysis of characteristic parameters of acoustic emission signals, combined with the observation of changes in the microstructure, made it possible to describe the corrosion processes. As the reaction progressed, signals with different characteristics were recorded, indicating aggregate cracking at the initial stage of the reaction, followed by cracking of the cement paste. The results, which were referred to the acoustic activity of reference mortars, confirmed that the reaction of opal aggregate with alkali was mitigated in mortars with lithium nitrate, and the applied acoustic emission method enabled the detection and monitoring of ASR progress.

Altitude Effects on the Performance of Small Radial Turbomachinery: Part I — Compressor Impellers

2016 ◽  
Author(s):  
Dries Verstraete ◽  
Kjersti Lunnan
Keyword(s):  
Reynolds Number ◽  
Performance Analysis ◽  
Rotational Speed ◽  
Pressure Ratio ◽  
Unmanned Aircraft ◽  
Good Match ◽  
One Dimensional ◽  
Design Changes ◽  
Current Article ◽  
The Impact

Small unmanned aircraft are currently limited to flight ceilings below 20,000 ft due to the lack of an appropriate propulsion system. One of the most critical technological hurdles for an increased flight ceiling of small platforms is the impact of reduced Reynolds number conditions at altitude on the performance of small radial turbomachinery. The current article investigates the influence of Reynolds number on the efficiency and pressure ratio of two small centrifugal compressor impellers using a one-dimensional meanline performance analysis code. The results show that the efficiency and pressure ratio of the 60 mm baseline compressor at the design rotational speed drops with 6–9% from sea-level to 70,000 ft. The impact on the smaller 20 mm compressor is slightly more pronounced and amounts to 6–10%. Off-design changes at low rotational speeds are significantly higher and can amount to up to 15%. Whereas existing correlations show a good match for the efficiency drop at the design rotational speed, they fail to predict efficiency changes with rotational speed. A modified version is therefore proposed.

Road barriers: modern solutions for improving traffic safety

2021 ◽  
pp. 43-48
Author(s):  
Keyword(s):  
Traffic Safety ◽  
Traffic Accident ◽  
Preventive Measures ◽  
Mechanical Damage ◽  
Road Accidents ◽  
Road Users ◽  
Urgent Task ◽  
The Moment ◽  
Energy Absorbing ◽  
The Impact

Improving the system of preventive measures aimed at reducing the severity of the consequences of road accidents is an urgent task. Road deaths are constantly increasing and there is a need for a comprehensive approach to creating safe road conditions. The purpose of this study is to analyze the promising designs of road barriers designed to prevent uncontrolled exit of vehicles from the roadway of the highway and to develop the design of energy-absorbing fencing. Barrier barriers must not only be safe for road users, but must also ensure their safety, as well as preserve the elements after hitting the fence. Analytical studies have shown that in order to reduce mechanical damage to vehicles and reduce the severity of injuries to the driver and passengers, it is necessary to develop a road fence design that allows you to extinguish the impact energy at the moment of contact between the car and the fence. Keywords: fencing, barrier, safety, traffic accident

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