SMA Actuator Payload Launch Lock Mechanism
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Solution Overview
Problem
Existing launch lock devices for spacecraft payloads transmit high loads to the payload during launch, potentially causing damage and have limited dynamic ranges of motion due to their design.
Innovation Solution
A payload launch lock mechanism featuring a base, a preload clamp, a fastener, and a shape memory alloy (SMA) actuator that elongates without fracturing, allowing the preload clamp to rotate or pivot and release the payload, thereby reducing shock transmission and increasing the payload's range of motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pyrotechnics or shape memory alloy are used to break a bolt for payload release, then the payload can be released reliably, but relatively high loads are transmitted to the payload causing potential damage
Solution Approach 1:
The clamp assembly is designed to pivot from a locked position to an unlocked position, transitioning from a rigid constraint to a rotational release mechanism. This dynamic movement allows the system to absorb and dissipate shock loads through the pivoting motion rather than transmitting them directly to the payload.
Solution Approach 2:
The fastener acts as an intermediary element between the clamp assembly and the base. It includes a fracture portion that can break to release the payload, but the breaking action occurs in the fastener rather than directly impacting the payload. The SMA actuator also serves as an intermediary that gradually elongates the fastener to reduce shock transmission.
2Strength
If a rigid clamp structure is used to restrain payload, then the payload is securely held during launch, but the payload has limited range of motion after release
Solution Approach 1:
The clamp assembly is designed to pivot from a locked position to an unlocked position, transitioning from a rigid constraint to a rotational release mechanism. This dynamic movement allows the system to absorb and dissipate shock loads through the pivoting motion rather than transmitting them directly to the payload.
Solution Approach 2:
The system changes the state of the fastener from intact to fractured, and the clamp assembly from locked to unlocked. These parameter changes enable the transition from a high-strength restraint state to a high-range-of-motion state, allowing the payload to have both secure holding during launch and freedom of motion after release.
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 mechanism effectively restrains payloads during launch and releases them with minimal shock transmission, enabling a larger range of motion compared to existing systems.
Implementation Method 1
The SMA actuator is adapted to receive electrical current and is configured, upon receipt of the electrical current, to supply a force that causes the fastener to elongate without fracturing
Data Source
AI summary
A payload launch lock mechanism includes a base, a preload clamp, a fastener, and a shape memory alloy (SMA) actuator. The preload clamp is configured to releasibly restrain a payload. The fastener extends, along an axis, through the preload clamp and into the base, and supplies a force to the preload clamp sufficient to restrain the payload. The SMA actuator is disposed between the base and the clamp. The SMA actuator is adapted to receive electrical current and is configured, upon receipt of the electrical current, to supply a force that causes the fastener to elongate without fracturing. The preload clamp, in response to the fastener elongation, either rotates or pivots to thereby release the payload.