New Generation Manned Spaceship Landing & Water Impact Test
This case details the successful impact strain test on the suspension system of the XX-type spacecraft landing gantry, conducted by a Space Electromechanical Research Institute in November 2024 using customized RU-846 Rugged Data Recorders. The test simulated the instantaneous impact during spacecraft release from the gantry under various working conditions, precisely measuring the dynamic strain response of the gantry's critical structures. This case highlights the exceptional performance of the RU-846 system in solving key technical challenges such as data acquisition in harsh environments, multi-channel synchronization, and transient signal capture. It demonstrates the significant value of this system in testing highly reliable aerospace ground equipment, providing critical data support and design validation for the safe landing of the spacecraft.
Keywords: Impact Strain Test; Spacecraft Landing Gantry; RU-846; Data Recorder; Strain Rosette; Aerospace Testing
Project Background and Challenges
With the continuous advancement of China's human spaceflight and deep space exploration missions, the safe recovery and landing of spacecraft are paramount. The landing gantry, serving as the core buffering and support structure during the spacecraft landing process, has a structural health status directly critical to the success of the entire mission. The impact load generated at the instant the spacecraft separates from the gantry is characterized by high intensity, transient nature (millisecond duration), and high energy, posing a severe test to the gantry structure.
1. Main challenges of this test:
1. Signal Transience: The impact event is extremely short-lived, requiring the acquisition system to have a very high sampling rate to accurately capture the complete waveform and avoid distortion.
2. Harsh Environment: The test site involved severe vibration, shock, and complex electromagnetic interference, demanding acquisition equipment with strong anti-interference capabilities and high physical protection ratings.
3. Deployment Complexity: The large-scale gantry structure had widely distributed measurement points, making traditional cabling to a central IPC cumbersome. Long-distance transmission also easily introduces noise.
4. Synchronization Requirement: Data from sensors distributed across various locations needed strict time synchronization to accurately analyze the propagation path and dynamic response of the impact load through the structure.
2. Test System Solution
To address these challenges, the project team selected customized RU-846 Rugged Data Recorders as the core data acquisition devices, building a distributed, offline test system.
2.1 Core Equipment: RU-846 Rugged Data Recorder
Rugged Design: Full metal enclosure with excellent shock and vibration resistance, ensuring stable operation in harsh test sites.
High-Performance Acquisition: Supports high sampling rates up to 100 kHz per channel with 24-bit resolution, fully meeting the need to capture transient impact signals.
Multi-Channel Synchronization: All channels feature strict synchronous acquisition, ensuring data time consistency across all measurement points, crucial for subsequent structural dynamics analysis.
Offline Independent Operation: Built-in high-capacity battery and high-speed solid-state storage allow operation independent of a computer. Parameters are set pre-test; data is downloaded post-test by retrieving the units, drastically simplifying field deployment and eliminating kilometers of cabling.
Broad Compatibility: Fully supports full-bridge, half-bridge, and quarter-bridge circuits, connects directly to strain rosettes, and provides built-in excitation voltage.
2.2 Measurement Point Layout and Sensor Selection
Over 50 measurement points were established on main load-bearing beams, stress concentration areas, and most critically, the buffer suspension connection points between the gantry and the landing plane. Three-element strain rosettes were installed at each point to measure plane stress state and calculate principal stresses and directions.
2.3 Test Condition Design
To comprehensively evaluate gantry performance, multi-dimensional simulated conditions were designed:
Variable 1: Impact Mass. Using counterweighted mock capsules of different masses.
Variable 2: Impact Height. Releasing the mock capsule from different heights to vary impact energy.
This combination systematically obtained response data under conditions ranging from "normal landing" to "extreme impact."
3. Test Process and Execution
System Deployment: Multiple RU-846 recorders were distributedly deployed in protective boxes on various sections of the gantry, connecting to nearby sensors to minimize cable length, signal attenuation, and noise.
System Configuration & Debugging: All RU-846 units were uniformly configured via Ethernet (sampling rate, range, filters, etc.) and synchronized for trigger linkage, ensuring all units were on "standby."
Trigger Setup: An acceleration threshold trigger mode was used. A high-g accelerometer connected to the master RU-846's trigger port initiated recording when the impact event exceeded a preset threshold. Pre-trigger functionality ensured data before the event was captured, perfectly recording the entire impact.
Test Execution: Drop tests were conducted for each condition, with RU-846 units recording data offline automatically.
Data Recovery & Analysis: Post-test, the RU-846 units were retrieved, and dedicated software was used to read all data files. Thanks to high-precision synchronization, all data aligned easily for import into professional software like nCode, LMS Test.Lab, or MATLAB for rosette calculation, stress contour generation, modal analysis, and fatigue life assessment.
4. Test Results and Value
The project team acquired unprecedented high-quality data:
Successfully captured the precise propagation path of the impact force through the gantry structure during buffer system operation.
Accurately measured the dynamic stress peaks and strain time histories at key locations under maximum impact, confirming the safety margin of the structural design.
Identified areas of local stress concentration under extreme conditions at specific connections, providing direct input for structural optimization.
Validated the energy dissipation efficiency and performance of the buffer suspension system, providing a data model for system improvements.
The RU-846 system, with its reliability, convenience, and high precision, successfully completed the test. Its "distributed, offline" test approach is hailed as a model for future large-scale structural testing.
5. Conclusion
The XX-type spacecraft landing gantry impact strain test demonstrates that the RU-846 Rugged Data Recorder is an ideal tool for measuring high-dynamic, transient physical parameters in complex environments. Its solution effectively overcomes the drawbacks of traditional methods, ensuring data integrity and accuracy. The critical data obtained not only directly serves this mission but also establishes analysis methods and a database that will provide vital reference for the design of next-generation landing systems, offering solid ground test technology support for the development of China's space industry.
