Abstract:

Objective This research aims to develop a dynamic deformation simulation method for weft-knitted fabrics based on physical constraints, addressing the complex interactions and morphological changes of yarns in knitted structures. The significance of this work lies in providing a new perspective for the design of knitted patterns, the development of simulation software, and the optimization of knitting processes.

Method The method of this research encompasses the development of a dynamic deformation simulation for weft-knitted fabrics based on a comprehensive physical model. The yarns are represented as a series of discrete capsule geometries, each corresponding to the physical properties of actual yarns. The simulation framework integrates several key components,including distance constraints to maintain yarn integrity and prevent over-extension, penalty functions to simulate yarn bending and ensure the yarn's resistance to deformation, collision constraints to prevent interpenetration of yarn segments ensuring that the simulated structure respects the physical space occupied by each yarn, and friction constraints to mimic the sliding behavior between yarns, which is essential for the stability of the knitted structure. Damping is introduced to dissipate kinetic energy and facilitate the convergence of the simulation to a stable state. The simulation leverages NVIDIA PhysX, a physics engine, to manage complex interactions and constraints. The process involves initializing capsule-shaped rigid bodies, applying constraints, and iteratively updating positions and rotations within a simulation loop to achieve a steady state of yarn-level knitting patterns. The simulation parameters and constraints are carefully calibrated to reflect the mechanical properties of the yarns and the structural characteristics of the knitted fabric. The algorithm iteratively updates the control points and render model to ensure that the deformation and motion of the fabric throughout the simulation are coherent and accurate. The simulation results are then compared with real samples to validate the accuracy and reliability of the model, providing a detailed and nuanced representation of weft-knitted fabric deformation.

Results The simulation results demonstrate the model's accuracy by comparing with real samples. The proposed method effectively simulates the interlocking structure of loops, frictional behavior between yarns, their elastic response, and collisions. The study provides a new perspective in the field of knitted fabric deformation simulation, showcasing the cop ability to simulate different knitted patterns with high fidelity. The physical constraints ensure the stability of the loop structure during deformation, allowing for elastic transformation and accurately reflecting the deformation characteristics such as bending, stretching, and twisting of yarns under external forces.

Conclusion The proposed physical constraint-based simulation method offers a precise and realistic representation of the deformation behavior of weft-knitted fabrics under various external forces. The consistency between the simulation results and the real fabric was demonstrated through a comparison with actual samples. This research is significant for the development of knitting pattern design software, simulation software development, and optimization of knitting processes. The findings also provide insights for future work in enhancing the simulation's efficiency and expanding its applicability to more complex fabric structures.

Key words: knitted fabric, deformation simulation, physical constraints, knitted pattern simulation, capsule body