When a person walks or runs while carrying a backpack, the pack sways in sync with the body; the greater the amplitude of this movement, the higher the acceleration, which significantly increases pressure on the shoulders. Furthermore, the backpack sways not only vertically but also laterally; the torque generated by this oscillation exerts a lateral pulling force on the spine, thereby heightening the wearer's discomfort.
Vibration table simulation tests were conducted to assess the ergonomic design, stability, and comfort of the backpack by simulating the swaying of shoulder straps during walking and running. The XTOP3D XTDIC-STROBE 3D dynamic measurement system was used to capture images during the tests, and DIC software was employed to analyze the data, yielding results such as 3D displacement, motion trajectories, velocity, and acceleration of the shoulder straps during movement.
The XTDIC-STROBE 3D dynamic measurement system offers solutions with various frame rate options and can be configured to suit specific testing scenarios. The system controls high-speed cameras to capture test images, tracking and calculating the shape, motion, and strain of every data point (subset of pixels) within the field of view. Because the data is calculated in three dimensions, out-of-plane displacement can be measured directly, yielding displacement data in the X, Y, and Z directions.
Adhesive Marker Measurement Module
The XTDIC-STROBE 3D dynamic measurement system tracks discrete markers (circular or bow-tie shaped) within a 3D coordinate system. While ensuring high-quality image acquisition, these lightweight, low-profile markers do not interfere with backpack shoulder straps or the mechanical response of the object, yet they allow for precise measurement of out-of-plane motion in the Y-direction.
Vibration Table Simulation Test Setup
In the vibration table simulation test, a dummy model wears the test backpack with the waist strap fastened. The vibration table simulates the motion of walking and running to evaluate the product's stability and oscillation characteristics during complex movements.
The XTDIC-STROBE 3D dynamic measurement system utilizes high-frame-rate cameras to capture the full range of motion of the shoulder straps and acquire 3D displacement data. This allows for an evaluation of whether the backpack and shoulder strap designs effectively minimize discomfort caused by swaying and optimize pressure distribution during movement.
Simulated Test Data Results
In the displacement test simulating a running motion, DIC technology was employed to track specially coded markers on the backpack shoulder straps. Images were captured using high-frame-rate cameras and processed via DIC software to determine the 3D displacement trajectories of the straps during movement. This enabled the analysis of key displacement data during the vertical cyclic motion of the vibration table and the assessment of the straps' dynamic behavior while running.
Ergonomically designed backpacks and shoulder/waist strap systems significantly reduce pressure on the shoulders and minimize strain on the spine. The XTOP3D XTDIC-STROBE 3D dynamic measurement system is utilized in vibration table tests that simulate the walking and running motions of a backpack wearer; it measures the 3D dynamic displacement and oscillation data of the shoulder strap model, providing a scientific basis for the ergonomic design of backpacks and their strap systems.
XTOP3D’s high-speed DIC technology fully captures the dynamic response of structures during transient impact events. When paired with high-frame-rate cameras, it acquires full-field data, while the accompanying DIC software analyzes full-field displacement and strain zones to deliver intuitive, precise, and visual results. This technology is widely applied in fields involving high-speed impact, vibration, deformation, motion, and rotation. These successful applications demonstrate that high-speed DIC technology will continue to play a pivotal role in the future, providing researchers and engineers with reliable test data for simulation validation and the assessment of a product's mechanical response and performance.
