Selectable Profile Energy Absorber for Helicopter Crash Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current energy absorber systems in helicopters, such as Fixed Load Energy Absorbers (FLEAs) and Fixed Profile Energy Absorbers (FPEAs), fail to effectively absorb kinetic energy for a wide range of occupant weights and sizes, leading to inadequate protection during crashes due to dynamic overshoot and inefficiencies in energy absorption, particularly for lighter or heavier occupants.
Innovation Solution
The Selectable Profile Energy Absorber (SPEA) system allows for the selection of tailored energy absorber profiles based on occupant weight and anticipated crash conditions, using a combination of fixed profile energy absorbers and aircraft-borne sensors to optimize the energy absorption process, minimizing dynamic overshoot and maximizing energy absorption efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Fixed Load Energy Absorbers (FLEAs) are designed for a reference occupant weight, then energy absorption is optimized for that specific weight, but performance deteriorates for occupants with different weights
Solution Approach 1:
The energy absorber system transitions from a fixed, static design to a dynamic, adjustable system. The stroke characteristic is made variable through selectable configurations that change the force-displacement profile based on detected occupant weight, allowing the system to adapt its energy absorption characteristics to match different occupant masses while maintaining optimal protection across the full weight range
Solution Approach 2:
The system changes key parameters of the energy absorber's force-stroke characteristic based on occupant weight. By detecting the actual occupant mass and selecting appropriate stroke profiles, the system adjusts the force-displacement relationship to ensure that the energy absorption matches the specific needs of each occupant weight category, preventing both under-protection and over-protection
2Use of energy by moving object
If the rate of onset is maximized to maximize energy under the EA force-time curve, then energy absorption capacity increases, but dynamic overshoot occurs due to spine compressibility
Solution Approach 1:
The energy absorption process is divided into distinct phases or periods. The stroke characteristic is designed with different stages: an initial phase with controlled rate of onset to prevent dynamic overshoot, followed by a main energy absorption phase, and potentially a final phase. This periodic approach allows the system to manage the timing of force application to match the dynamic response of the occupant's spine
Solution Approach 2:
The system prepares the energy absorption profile in advance based on predicted or detected crash conditions and occupant characteristics. By pre-selecting the appropriate stroke characteristic before the crash occurs, the system ensures that the rate of onset is appropriately controlled from the beginning of the event, preventing dynamic overshoot before it can occur while still maximizing overall energy absorption
3Force
If energy absorbers stroke at constant force for a reference occupant, then lighter occupants experience excessive deceleration forces, but heavier occupants require longer stroke distances that may not be available
Solution Approach 1:
The stroke distance is made variable through selectable configurations. Instead of a fixed stroke length, the system offers multiple predetermined stroke characteristics with different maximum stroke distances. The appropriate stroke distance is selected based on the detected occupant weight, ensuring that lighter occupants receive adequate force control while heavier occupants are provided with sufficient stroke distance to absorb their greater kinetic energy
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The SPEA system provides near-optimal deceleration forces for all occupants, maximizing energy absorption while minimizing spinal loading, thus enhancing occupant safety and survivability in severe crashes by using the entire available stroke distance effectively.
Implementation Method 1
energy absorbers are made to absorb as much energy as possible at loads that are survivable but which stop the seat and occupant before contact with the floor of the vehicle
Implementation Method 2
The movement of the seat is referred to as stroking and its movement, or stroke, is resisted by the force/s applied by Energy Absorbers (EAs), elongating the stopping distance while absorbing crash energy
Data Source
AI summary
A method and apparatus for protecting a passenger during a crash comprises a moveable seat with an energy absorber (EA) that allows the seat to stroke a finite distance to decelerate the passenger in a controlled manner. The seat is designed so that one of a plurality of fixed profile EA's can be selectively engaged to provide a tailored EA composite profile adapted to the occupant's weight and anticipated crash environment. The tailored EA composite profile applies a frequency matched, low onset force to the seat, which substantially eliminates problems associated with dynamic overshoot of the passenger's spine.