scholarly journals Windblast testing of an aircrew helmet: An approach to neck load analysis

2020 ◽  
Vol 63 ◽  
pp. 77-82
Author(s):  
NK Tripathy ◽  
N Divya ◽  
V Raghunandan
Keyword(s):  
Structural Integrity ◽  
Test Facility ◽  
Performance Limits ◽  
Fighter Aircraft ◽  
Injury Criteria ◽  
Test Conditions ◽  
Entire Duration ◽  
Hybrid Iii ◽  
Total Exposure Time ◽  
Structural Failures

Introduction: Modern generation fighter aircraft has expanded the escape envelope for a fighter aircrew. With the ejection occurring at very high airspeeds, windblast is a cause of major injuries and fatalities. Flying helmet, before its induction into operational usage, must be tested in simulated windblast conditions to ensure that they provide adequate safety. Material and Methods: Windblast tests were conducted on a newly designed/procured helmet in a standard windblast test facility as per Mil Std MIL-V-29591/1. A large instrumented Hybrid III male dummy was used for the tests. The test conditions were: Wind speed 600 ± 60 KEAS, rise time of 125 ± 20 ms, time at peak wind velocity of 300 ± 50 ms, and total exposure time of ≥3 s. Structural integrity, retention with the headform, and recorded neck loads were assessed for interpretation of test results. Results: Helmets could withstand the windblast conditions without any significant structural failures and were retained with the headform during the entire duration of test conditions. However, analysis of the neck loads resulted in a significant dilemma in aeromedical decision-making, there being no laid down criteria in the Mil Specification. The neck tension forces were more than the acceptable limits and found to have the potential for significant neck injuries as per the Injury Assessment Reference Values specified in AGARD-AR-330 specifically in the tests where blast was head on and outer visor in up configuration; however, these values were within the acceptable limits as per the other proposed criteria. Similarly, analysis of the neck tension extension combined effects revealed conflicting outcomes for Nij performance limits specified in various standards. This paper discusses the critical analysis of neck loads vis-à-vis the neck injury criteria to understand the neck loads generated during windblast conditions and its implication on aircrew safety. Conclusion: Neck loads assessment is critical in predicting aircrew safety during windblast testing. In the absence of a clearly defined criteria in the Mil Specification, critical ananlysis of neck loads vis-à-vis recommended standards in scientific literature be done to make meaningful conclusion.

Injury criteria of the IMO and the Hybrid III dummy as indicators of injury potential in free-fall lifeboats

1996 ◽  
Vol 23 (5) ◽  
pp. 385-401 ◽  
Author(s):  
James K. Nelson ◽  
Peter J. Waugh ◽  
Alan J. Schweickhardt
Keyword(s):  
Free Fall ◽  
Injury Criteria ◽  
Hybrid Iii ◽  
Injury Potential

scholarly journals Experimental Study on the Effect of Heel Plate Length on the Structural Integrity of Cold-formed Steel Roof Trusses

2018 ◽  
Vol 65 ◽  
pp. 08010
Author(s):  
Je Chenn Gan ◽  
Jee Hock Lim ◽  
Siong Kang Lim ◽  
Horng Sheng Lin
Keyword(s):  
Ultimate Load ◽  
Structural Integrity ◽  
Load Capacity ◽  
Local Buckling ◽  
Ultimate Capacity ◽  
Ultimate Load Capacity ◽  
Plate Length ◽  
Roof Truss ◽  
Cold Formed Steel ◽  
Structural Failures

Applications of Cold-Formed Steel (CFS) are widely used in buildings, machinery and etc. Many researchers began the research of CFS as a roof truss system. It is required to increase the knowledge of the configurations of CFS roof trusses due to the uncertainty of the structural failures regarding the materials and rigidity of joints. The objective of this research is to investigate the effect of heel plate length to the ultimate load capacity of CFS roof truss system. Three different lengths of heel plate specimens were fabricated and subjected to concentrated loads until failure. The highest ultimate capacity for the experiment was 30 kN. The results showed that the increment of the length of the heel plate had slightly increased the ultimate capacity and strain. The increment of the length of the heel plate had increased the deflection of the bottom chords but decreased the deflection of the top chords. Local buckling of top chords adjacent to the heel plate was the primary failure mode for all the heel plate specimens.

Design and Validation of a Component Head Injury Criteria Tester for Aerospace Applications

2005 ◽  
Author(s):  
Hamid M. Lankarani ◽  
C. S. Koshy ◽  
C. K. Thorbole
Keyword(s):  
Head Injury ◽  
Seat Belt ◽  
Impact Angle ◽  
Head Impact ◽  
Aircraft Cabins ◽  
Aerospace Applications ◽  
Injury Criteria ◽  
Test Conditions ◽  
Head Injury Criteria ◽  
Impact Events

The compliance with Head Injury Criteria (HIC) specified in 14 CFR 23.562 [1] and CFR 25.562 [2] poses a significant problem for many segments of the aerospace industry. The airlines and the manufacturers of jet transports have made claims of high costs and significant schedule overruns during the development and certification of 16G seats because of the difficulties encountered in meeting this requirement. The current practice is to conduct Full Scale Sled Tests (FSST) on impact sleds. This approach can be expensive, since a new seat may be needed for each test. Moreover, some consider the HIC sensitive to changes in the test conditions, such as sled pulse, seat belt elongation, etc., resulting in HIC results from FSSTs showing poor repeatability. These difficulties make it desirable to devise a cheaper, faster, and more repeatable alternative to FSSTs. This paper describes an attempt to address these issues by designing a device, the National Institute for Aviation Research (NIAR) HIC Component Tester (NHCT) using various multibody tools. This device was then fabricated and its performance evaluated against FSSTs conducted under similar test conditions for some typical impact events that occur in an aircraft cabins e.g. impact with bulkheads. The factors compared for this evaluation are the head impact angle, head impact velocity, HIC, HIC window, peak head C.G. resultant acceleration, average head C.G. resultant acceleration, and head C.G. resultant acceleration profiles. The results of these evaluations show that the NHCT already produces test results that correlate significantly with FSST results for impact targets such as bulkheads and its target envelope is expected eventually to include objects such as seat backs.

Responses of Hybrid-III 50th and Thor-NT 50th in Sled Tests With Different Seat Belt Pretensioner Configurations

2006 ◽  
Author(s):  
Chang In Paek ◽  
Greg Shaw ◽  
Jeff Crandall ◽  
Yoon Ho Baek ◽  
Ol Suk Ko
Keyword(s):  
Head Injury ◽  
Seat Belt ◽  
Relative Sensitivity ◽  
Forward Movement ◽  
Similar Test ◽  
Injury Criteria ◽  
Hybrid Iii ◽  
Head Injury Criteria ◽  
Test Repeatability

This study quantifies the effectiveness of the various seat belt pretensioner configurations relative to the no pretensioner condition and defines the relative sensitivity of the Hybrid-III 50th and THOR-NT 50th percentile male anthropomorphic test devices to pretensioner effects. The results of this study indicate that pretensioners reduced the chest accelerations and Head Injury Criteria (HIC) of both Hybrid-III and THOR-NT dummies. In addition, the pretensioners reduced the chest forward movement by providing restraint earlier in the event. The dual pretensioners and the retractor pretensioners were more effective than the buckle pretensioner and the no pretensioner conditions. Although the Hybrid-III and THOR-NT were different in construction and sitting depth, the Hybrid-III and THOR-NT's responses to the pretensioner conditions were similar. Test-to-test repeatability was acceptable for both dummies.

Effect of Head Restraint Position and Neck Injury Criteria in Rear Impact

2002 ◽  
Author(s):  
John DeRosia ◽  
Narayan Yoganandan ◽  
Frank A. Pintar
Keyword(s):  
Motor Vehicle ◽  
Vehicle Safety ◽  
Bending Moments ◽  
Safety Standards ◽  
Acceleration Pulse ◽  
Head Restraint ◽  
Rear Impact ◽  
Injury Criteria ◽  
Hybrid Iii ◽  
Impact Acceleration

The objective of this study was to determine the forces and bending moments at the top of the Hybrid III dummy neck secondary to rear impact acceleration and evaluate the various proposed injury criteria. Rear impact sled tests were conducted by applying the Federal Motor Vehicle Safety Standards FMVSS 202 acceleration pulse. Differing positions of the head restraint in terms of height (750 and 800 mm) and backset (zero, 50, and 100 mm) were used to determine the axial and shear forces, bending moments, and injury criteria (NIC, Nij, and Nkm). The time sequence of attainment of these parameters was determined along with peak values.

Design and Implementation of a Digital Multimode H∞ Controller for the Spey Turbofan Engine

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Raza Samar ◽  
Ian Postlethwaite
Keyword(s):  
Degrees Of Freedom ◽  
Structural Integrity ◽  
Controller Design ◽  
Reference Model ◽  
Test Facility ◽  
Engine Test ◽  
Control Logic ◽  
Turbofan Engine ◽  
Simple Strategy ◽  
Bumpless Transfer

In this paper, a 2 degrees-of-freedom multimode controller design for the Rolls Royce Spey turbofan engine is presented. The controller is designed via discrete time H∞-optimization; it provides robust stability against coprime factor uncertainty, and a degree of robust performance in the sense of making the closed-loop system match a prespecified reference model. Multimode control logic is developed to preserve structural integrity of the engine by limiting engine variables to specified safe values. A simple strategy for antiwindup and bumpless transfer between controllers, based on the Hanus anti-windup scheme (1987, “Conditioning Technique, A General Anti-Windup and Bumpless Transfer Method,” Automatica, 23(6), pp. 729–739) and the observer-based structure of the controller, is presented. The structure of the overall switched controller is described. Actual engine test results using the Spey engine test facility at Pyestock are presented. The controller is shown to perform a variety of tasks, its multimode operation is illustrated and improvements offered on existing engine control systems are discussed.

Sign in / Sign up

Export Citation Format

Share Document