Human Effectiveness Directorate

The Biodynamics Team, part of the Air Force Research Laboratory’s 711th Human Performance Wing has the primary objective to develop and optimize aircrew injury criteria and protection equipment by studying the effects of impact acceleration on instrumented Anthropometric Test Devices (ATDs), volunteer human subjects, and Post-Mortem Human Subjects (PMHS). The goal is to deliver validated injury criteria and equipment assessments to Air Force Life Cycle Management Center (AFLCMC) for use in military standards used to verify equipment integration into aircraft. Benefits to the warfighter include improved assessment of injury risk leading to improvements in aircraft ejection seats, aircrew restraint configurations, and helmet systems that mitigate acute neck and spine injury in high-performance, bomber, and heavy-lift aircraft.

Email:
AFRLBiodynamicsLab@us.af.mil

Address:
2800 Ascani St., Wright Patterson Air Force Base, OH 45433

Horizontal Impulse Accelerator (HIA)
The HIA is a 160-foot track used to conduct horizontal impact acceleration tests in either a single axis or in multiple axes to evaluate instrumented ATD and volunteer human subject dynamic response while restrained various aircrew seats, and to evaluate the structural integrity of aircrew flight equipment. The HIA, shown in figures below, consists of a thrust piston, actuator/pressure chambers, an impact sled, and track rails. The principle of operation is based on high-pressure energy stored in the actuator to accelerate the sled down the track, with the amount of energy applied to the thrust piston controlling the acceleration of the sled.

AFRL HIA Impact Acceleration Facility with Human Subject (Left) and ATD (Right) and Sled in Stationary Position Prior to Start of Impact to Accelerate ATD Down the Track

Recently, NASA worked with the Biodynamics Team at AFRL’s Human Effectiveness Directorate to test the suit for the astronauts and the seating system with the emphasis on the structural design of the seat and the restraint configuration. The HIA tested multiple landing scenarios to gauge how the high-energy, low duration events inherent to the Orion spacecraft’s landings might affect the crew of the Artemis II mission. Using only parachutes to reduce speed, the Orion crew module will slow from nearly 25,000 miles per hour to around 20 during reentry and splashdown in the Pacific Ocean. The HIA allowed AFRL and NASA to assess various landing impact scenarios across all three coordinate axes(x, y, z) of the seat and enabled researchers to examine how the seats and flight suits interact with one another and what affect those interactions may have on the crew. This allows crew safety personnel to address any issues that may present themselves in a more cost-effective manner than other testing options. Another advantage is being able to run the system in a laboratory environment, where multiple tests in various orientations and configurations can be assessed. This gives the testing team an idea of potential areas of crew injury and allows changes to be made.

“This horizontal accelerator is currently the only known facility of its kind that can conduct extensive biodynamic research on instrumented [anthropometric test device, or] ATDs and volunteer human subjects.” -Chris Perry, senior biomedical engineer, Biodynamics Section, 711th Human Performance Wing

Additional information on the HIA in the news:

AFRL helps NASA wrap up equipment testing for Artemis II mission.
- https://www.afrl.af.mil/News/Article-Display/Article/3672146/afrl-helps-nasa-wrap-up-equipment-testing-for-artemis-ii-mission/
AFRL helps NASA test equipment for Artemis II mission.
- https://www.afrl.af.mil/News/Article-Display/Article/3406398/afrl-helps-nasa-test-equipment-for-artemis-ii-mission/
Vertical Deceleration Tower (VDT)
The VDT, also called the drop tower, is a 50-foot tower used to conduct vertical impact acceleration tests in a single axis or in multiple axes to evaluate instrumented ATD and volunteer human subject dynamic response while restrained various aircrew seats, and to evaluate the structural integrity of aircrew flight equipment. The VDT, shown in figures below, consists of two vertical rails, a drop carriage, a water cylinder at the base of the tower, and shaped plungers mounted on the carriage. The principle of operation is based on raising the drop carriage to a specified height and then allowing it to enter free-fall, and the resulting impact of the carriage-mounted plunger with the water filled cylinder produces the desired acceleration input.

AFRL VDT Impact Facility with ATD Subject Prior to Raising Drop Carriage(Left), and Carriage with ATD at Required Drop Height Prior to Free-Fall (Right)

Recently, NASA worked with the Biodynamics Team on the VDT as part of a research collaboration agreement supporting the development of their Orion space capsule. This study was first to use both human subjects and instrumented ATDs as test subjects wearing Orion space suits and then integrated with the Orion seat for impact testing. The impacts with the seat are part of the larger effort investigating the overall safety and integrity of the seats and related occupant equipment for future missions related to NASA’s Artemis program. Detailed analysis of ATD and human subject electronic data and critical review of motion analysis using high-speed video will be used for computational modeling and for an assessment of crew injury risk. This will ultimately aid NASA’s and AFRL’s design and development of restraint and protection equipment for current and future air and space vehicles.
Vertical Impact Device (VID)
The VID is a 16.5 foot tower used to conduct very high-energy, short-duration, impact acceleration tests to evaluate instrumented ATD and volunteer human subject dynamic response while restrained various aircrew seats, and to evaluate the structural integrity of aircrew flight equipment. The VID, shown in figures below, consists of two vertical rails, a drop carriage, impact energy attenuators, and an impact base. The principle of operation is similar to the VDT, and is based on raising the drop carriage to a specified height and then allowing it to enter free-fall. The resulting impact of the carriage striking the impact energy attenuators, typically high-density felt pads or polyurethane disks, mounted on top of the base produces the desired acceleration input.

AFRL VID Impact Facility with Carriage and ATD Subject at Required Drop Height Prior to Free-Fall (Left), and Close-up of Felt Impact Attenuators (Right)

Recently, Collins Aerospace worked with the Biodynamics Team on the VID as part of a research effort to conduct an impact assessment of modified Goodrich Interior pilot seat to evaluate their ability to attenuate energy from a pure vertical impact. The main modification to the seat involved integration of an energy attenuation (EA) system that allowed the seat to stroke during vertical impact. The program consisted of very high-energy vertical impacts with the impacts representing the downward, vertical impact described in MIL-S-58095A.
Vertical Impulse Accelerator (VIA)
The VIA is a 25-foot vertical tower used to conduct impact acceleration tests in either a single axis or in multiple axes to evaluate instrumented ATD dynamic response while restrained various aircrew seats, and to evaluate the structural integrity of aircrew flight equipment. The VIA, shown in figures below, consists of twin vertical rails, a thrust piston, actuator/pressure chambers, and an impact carriage. The principle of operation is based on high-pressure energy stored in the actuator to accelerate the carriage up the rails from an initial stationary position, with the amount of energy applied to the vertical thrust piston controlling the acceleration of the carriage.

AFRL VIA Impact Acceleration Facility with ATD Subject in Test Seat and Carriage in Stationary Position Prior to Start of Impact to Accelerate ATD Up the Rails

Recently, the Navy’s Amphibious Warfare Program Office worked with the Biodynamics Team on the VIA as part of a research effort for evaluating the shock mitigating characteristics of the seats for the Pilot/Co-pilot and the seats for the Deck Crewmembers of the Ship to Shore Connector (SSC) craft. The SSC was being developed to replace the Navy’s Landing Craft, Air Cushion (LCAC) and will provide amphibious transport to Joint Forces. This testing was proposed and developed as part of the SSC Live Fire Program and will help resolve critical issues related to the crew’s vulnerability to land and surf zone mines.
Six Degree of Freedom (SIXMODE) Vibration System
The SIXMODE Vibration System allows for the evaluation of human responses during single and multi-axis whole-body vibration in the translational directions (X, Y, and Z) and in the angular directions (roll, pitch, and yaw). Evaluations focus on understanding how humans interact with different interfacing equipment such as aircrew seating systems, patient litter configurations, and personal protective gear by studying their combined responses. The SIXMODE is capable of recreating time histories recorded on aerospace and ground vehicles, allowing for the inexpensive recreation and repetition of vehicle operation conditions in a controlled environment for proof-of-concept studies. The SIXMODE is also capable of generating a variety of waveforms including sinusoidal, sum-of-sines, random vibration, and pre-programmed signatures.

AFRL SIXMODE Vibration Facility setup for Spine Immobilization Study (left), Vibration Facility with Human Subject being prepared for test

The Biodynamics Section recently completed a collaborative study with NAMRU-D with the purpose of defining how the mechanisms and pathways of vibration experienced by aircrew during operation of military rotary-wing/tilt-rotor aircraft contribute to musculoskeletal pain and injury. The objective of the study was to quantify the relationship among the measured factors, such as acceleration, duration, fatigue, and torso muscle activity when exposed to operationally relevant vibration. The goal of the study was to better understand the biomechanical and physiological mechanisms that potentially contribute to Lower Back Disorders (LBD) and identify the degree to which these vibration characteristics must be mediated to significantly reduce LBD risk.

In addition to internal impact facility Test and Evaluation support, the Biodynamics Team can provide instrumented advanced technology development and subject matter expert support for the execution of external high speed ejection seat rocket sled testing or other impact testing requiring ATD data collection and injury analysis. If un-instrumented ATDs are required for a specific test series, the team also offers an ATD rental service to third party customers without requiring personnel. The Biodynamics Team can also provide services to groups operating their own ATDs or impact facilities by providing support for sensor calibration such as linear accelerometers, angular accelerometers, angular rate sensors and load cells.

Apart from impact centric technical support, they also provide an extensive mass properties lab for articles ranging from single helmet and helmet mounted display configurations, to fully seated occupant and ejection seat mass properties. The mass properties data collection consists of the measurement of the weight, principal moments of inertia (MOI), and the center of gravity (CG) of the item under test. The test equipment consists of an electronic scale, reaction table assembly with knife edge blades for CG measurement, and an inverted torsional pendulum for MOI measurements.

The Biodynamics Team also has a Helmet Impact tower (HIT) which is a vertical drop tower designed to produce vertical impact acceleration and velocity profiles to assess the performance of helmets, impact energy attenuation systems, and integrated helmet technologies. The primary objectives include establishing helmet standards, evaluating the characteristics of helmet systems, and conducting comparative analyses of current and proposed helmet designs. The facility comprises a vertical steel mono-rail, an impact carriage equipped with a head-form, and fixed impactors. The head-form and carriage are released into a free-fall from a specified height, colliding with a stainless-steel impactor to achieve the necessary impact velocity or energy.

They also include anthropometry measurements using Vitronic VITUS 3D body scanner, portable 3D scanning with Artec LEO, and 3D metrology using FARO and Hexagon Romer arms. These capabilities can be combined with the mass properties measurement capabilities of the team to provide reverse engineering services for part geometry generation or simulation development.

BIODYNAMICS LAB

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