Gravity Drop Tower for High Strain Rate Polymer Testing
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Solution Overview
Problem
Conventional high strain rate testing systems experience ramp-up time delays, introduce noise, and are poorly designed for testing polymers, limiting their ability to perform tension, compression, shear, and large strain tests effectively.
Innovation Solution
A gravity-driven drop tower system with a motorized winch, high-speed optical sensors, and piezo-electric load sensors, designed with extruded aluminum frames and adaptable test fixtures for tension and compression testing, allowing for rapid testing across various strain rates and modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional high strain rate testing systems are used, then testing capability is provided, but ramp-up time is excessive and initial data is not at higher rates
Solution Approach 1:
The sled is pre-positioned at a measured distance above the sample using the winch, and the drop height is precisely controlled before release. This preliminary positioning allows the system to achieve high strain rates immediately upon release without requiring ramp-up time, as the impact velocity is predetermined by the gravitational drop from the measured height.
2Measurement precision
If conventional testing systems are used, then testing is performed, but noise is introduced and data uncertainty increases
Solution Approach 1:
The harmful noise and vibration generated during impact are extracted and isolated from the measurement system through careful fixture design and sensor placement. The fixture is designed to minimize noise transmission while allowing accurate measurement of impact forces and material response, separating the harmful vibrations from the useful measurement data.
3Adaptability or versatility
If conventional fixtures are used, then testing is possible, but the system is bulky and poorly designed for polymer testing
Solution Approach 1:
The test fixture is designed as a universal, multi-functional component that can accommodate various test modes including tension, compression, shear, and large strain testing of polymers. The fixture incorporates adjustable components and modular elements that allow it to adapt to different testing requirements without requiring separate specialized fixtures for each test type, reducing overall system complexity while increasing versatility.
4Adaptability or versatility
If conventional systems are used, then testing is performed, but tension, compression, shear and other test modes are difficult to test with one system
Solution Approach 1:
The fixture incorporates dynamic, adjustable components that can be reconfigured between different test modes. The upper and lower fixtures can be positioned and secured in various configurations to accommodate tension, compression, and shear testing. This dynamic reconfigurability allows a single system to perform multiple test modes easily by simply adjusting the fixture positions and securing mechanisms rather than requiring complex tool changes.
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 system achieves lower ramp-up times, reduced noise, and enhanced capability for testing polymers and other materials at high strain rates, enabling efficient tension, compression, and shear testing with improved data accuracy.
Implementation Method 1
The winch of the top member raises the sled to a desired height, the sled is released at the desired height and slides along the rails resulting in an impact on a sample placed in the test fixture
Implementation Method 2
the sled is released at the desired height and slides along the rails resulting in an impact on a sample placed in the test fixture
Implementation Method 3
the test fixture further includes a piezo-electric load sensor configured to measure impact on the sample and triggered by the triggering system
Data Source
AI summary
A drop tower apparatus and method of use is provided. The drop tower apparatus includes a base, a frame, a top member, rails, a sled, a triggering system, and a test fixture. The frame extends from the base. The top member is disposed on the frame opposite the base and has a winch. The rails extend from the base to the top member and are disposed within the frame. The sled is configured to slide vertically along the length of the rails and is releasably connected to the winch of the top member. The test fixture is configured to receive a sample for testing. The winch of the top member raises the sled to a desired height, the sled is released at the desired height and slides along the rails resulting in an impact on a sample placed in the test fixture.