Soft-walled microchannels arise in many applications, ranging from organ-on-a-chip platforms to soft-robotic actuators. However, despite extensive research on their static and dynamic response, the potential failure of these devices has not been addressed. To this end, we explore fluid--structure interaction in microchannels whose compliant top wall is governed by a nonlocal mechanical theory capable of simulating both deformation and material failure. We develop a one-dimensional model by coupling viscous flow under the lubrication approximation to a state-based peridynamic formulation of an Euler--Bernoulli beam. The peridynamic formulation enables the wall to be modeled as a genuinely nonlocal beam, and the integral form of its equation of motion remains valid whether the deformation field is smooth or contains discontinuities. Through the proposed computational model, we explore the steady and time-dependent behaviors of this fluid--peridynamic structure interaction. We rationalize the wave and damping dynamics observed in the simulations through a dispersion (linearized) analysis of the coupled system, finding that, with increasing nonlocal influence, wave propagation exhibits a clear departure from classical behavior, characterized by a gradual suppression of the phase velocity. The main contribution of our study is to outline the potential failure scenarios of the microchannel's soft wall under the hydrodynamic load of the flow. Specifically, we find a dividing curve in the space spanned by the dimensionless Strouhal number (quantifying unsteady inertia of the beam) and the compliance number (quantifying the strength of the fluid--structure coupling) separating scenarios of potential failure during transient conditions from potential failure at the steady load.

翻译：软壁微通道在诸多应用领域中广泛存在，从芯片器官平台到软体机器人执行器均可见其身影。然而，尽管已有大量研究关注其静态与动态响应，这些装置的潜在失效问题尚未得到充分探讨。为此，我们研究了微通道中的流固耦合问题，其中柔性顶壁采用能够模拟变形与材料失效的非局部力学理论进行描述。通过将润滑近似下的黏性流动与基于状态的欧拉-伯努利梁近场动力学表述相耦合，我们建立了一维模型。该近场动力学表述使得壁面能够被建模为真正的非局部梁，其运动方程的积分形式在变形场无论平滑还是包含间断时均保持有效。通过所提出的计算模型，我们探究了这种流体-近场动力学结构相互作用的稳态与时变行为。通过对耦合系统进行色散（线性化）分析，我们合理解释了模拟中观察到的波动与阻尼动力学现象，发现随着非局部效应的增强，波传播行为明显偏离经典特征，表现为相速度的逐渐抑制。本研究的主要贡献在于系统阐述了微通道软壁在流体动载荷作用下可能发生的失效场景。具体而言，我们在由无量纲斯特劳哈尔数（量化梁的非定常惯性）与柔度系数（量化流固耦合强度）张成的参数空间中，发现了一条分界曲线，该曲线将瞬态工况下的潜在失效场景与稳态载荷下的潜在失效场景区分开来。