Dynamic Friction Testing Device with Stepped Incident Bar
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Solution Overview
Problem
Conventional Hopkinson torsion bars can only perform instantaneous single loading on specimens, failing to simulate the complex stress environments encountered by materials in engineering applications where multiple loadings occur.
Innovation Solution
A dynamic friction experimental device with a coaxially arranged incident bar featuring two sections of differing cross-sectional areas, combined with an axial compression device and torque loading device, allows for multiple continuous dynamic torque loadings with varying amplitudes, mimicking real-world stress conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional Hopkinson torsion bar is used, then the structure is simple and easy to operate, but it can only perform instantaneous single loading on the specimen
Solution Approach 1:
The incident bar is divided into two sections with different cross-sectional areas. The first section (closer to the specimen) has a smaller cross-sectional area, while the second section (farther from the specimen) has a larger cross-sectional area. This segmentation allows the system to perform multiple continuous dynamic torque loadings with different amplitudes on the specimen, transforming a single-loading device into a multi-loading capability device while maintaining structural simplicity
Solution Approach 2:
Different sections of the incident bar are given different local properties (different cross-sectional areas). The first incident section has a smaller cross-sectional area suitable for transmitting torque to the specimen, while the second incident section has a larger cross-sectional area that forms a reflecting interface. This local quality differentiation enables the bar to both apply torque and reflect torsional waves for multiple loading cycles
2Adaptability or versatility
If the incident bar has a uniform cross-sectional area, then the structure is simple, but it cannot reflect torsional waves for multiple loadings
Solution Approach 1:
The incident bar transitions from a symmetric (uniform cross-section) design to an asymmetric design with two different cross-sectional areas. The first incident section has cross-sectional area A1 and the second incident section has cross-sectional area A2, where A1 < A2. This asymmetric structure creates a reflecting interface at the joint between sections, enabling torsional wave reflection for multiple continuous loadings while maintaining a simple stepped geometry
3Adaptability or versatility
If a single incident bar configuration is used, then the device is simple to manufacture, but it cannot apply torque in the form of multiple continuous dynamic loadings
Solution Approach 1:
The incident bar is manufactured as two separate sections with different cross-sectional areas that are then connected. The first incident section and second incident section can be fabricated independently and then joined together, making the manufacturing process straightforward while achieving the complex function of multiple continuous dynamic torque loadings through the reflected torsional waves
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
Enables measurement of mechanical parameters under composite loading conditions, providing data closer to actual stress environments, thus aiding engineering design and calculation.
Implementation Method 1
the second incident section forms a reflecting interface on an end face facing the first incident section; after the torque is conducted to the specimen through the second incident section and the first incident section in the form of the torsional wave, a part of the torsional wave is reflected to the first incident section and the second incident section
Implementation Method 2
the energy stored in the incident bar is transmitted to a specimen in a form of a wave to complete the loading of the specimen
Data Source
AI summary
A dynamic friction experimental device includes a base, an incident bar, an axial compression device, and a torque loading device. The base is provided with a displacement-constrain structure, and the incident bar includes a first incident section and a second incident section. The first incident section is arranged adjacent to the displacement-constrain structure, and the second incident section is connected to the first incident section. At a joint of the first incident section and the second incident section, a projection of a cross section of the first incident section is positioned in a cross section of the second incident section along an axial direction of the second incident section. When the dynamic mechanical property of a specimen is tested, the axial compression device is configured to apply pressure to the second incident section, and the torque loading device is configured to apply torque to the second incident section.