As a crucial component to ensure the safety and reliability of lithium-ion batteries (LIBs), the polymer separator plays a significant role in ensuring the mechanical abuse safety of the battery, and its mechanical properties have become an important indicator of battery safety performance. This study focuses on the compressive mechanical behavior of separators in prismatic power batteries under coupled strain rate and temperature conditions. Quasi-static and dynamic compression experiments were conducted under a wide range of strain rates and temperatures. These tests assessed the mechanical behavior and damage mechanism of separator at elevated temperatures and different strain rates. The strain rate-dependent and temperature-dependent mechanical properties of the separator was meticulously explored. The results indicated that the mechanical behavior of separator is highly sensitive to both the strain rate and the temperature. As the strain rate increases, the yield point of the separator decreases. Additionally, both the elastic modulus and the yield stress of the separator decrease as the temperature. At low strain rates, the yield point shifts forward, whereas at high strain rates, the yield strain increases with the temperature. Additionally, the coupled effects of temperature and strain rate were found to alter the damage failure modes, subsequently affecting the separator’s mechanical properties and structural integrity. At low strain rates, the failure of the separator is primarily characterized by plastic deformation and local buckling, whereas complex dynamic failure modes may occur at high strain rates. Based on experimental data, a nonlinear viscoelastic constitutive model was developed, incorporating the effects of temperature-strain rate coupling. This model offers essential insights for the safe and optimized design of lithium-ion batteries. The comprehensive experimental analysis and model developed in this study provide critical references for advancing the design, manufacturing, and practical application of LIB separators, enhancing their reliability and safety across a diverse range of operational conditions.

To investigate the response and damage behavior of composite aero-engine blades under bird-strike events, an equivalent bird-strike testing method was proposed in which a component-level flat plate specimen was used to replace a full-scale fan blade. The method aims to reproduce the trailing-edge delamination damage observed in full-scale blades during bird strike. Bird-strike tests and corresponding numerical simulations on the plate specimens under different clamping configurations were conducted, and the impact response characteristics as well as the initiation and propagation processes of delamination were systematically analyzed for each configuration. Based on these results, a component-level equivalent test methodology capable of effectively simulating trailing-edge delamination in blade bird-strike scenarios is proposed. A baseline impact condition that induces single-side trailing-edge delamination in a representative composite laminate is identified, including impact height, impact velocity, and the bird-cut ratio (defined as the percentage of the effective impacting volume of the bird projectile relative to its total volume at the instant of impact). In addition, by comparing test and numerical results under various impact conditions, the accuracy of the numerical model is validated. Using the experimentally validated model, sensitivity analyses were performed with respect to the test parameters (impact height, impact velocity, and bird-cut ratio). The results show that, within the controllable ranges of parameter variation in the tests, the changes in key impact response metrics of the composite plate—namely the peak displacement at the upper trailing edge, the peak displacement at the lower trailing edge, and the displacement difference along the upper edge—are all less than 5% relative to the baseline condition. This study demonstrates that the proposed equivalent testing method enables a composite plate test to replicate the local displacement response and delamination pattern of a full-scale blade under bird strike, and the test outcomes exhibit good robustness.

In challenging operational environments, Lithium-ion batteries (LIBs) inevitably experience mechanical stresses, including impacts and extrusion, which can lead to battery damage, failure, and even the occurrence of fire and explosion incidents. Consequently, it is imperative to investigate the safety performance of LIBs under mechanical loads. This study is grounded in a more realistic coupling scenario consisting of electrochemical cycling and low-velocity impact. We systematically and experimentally uncovered the mechanical, electrochemical, and thermal responses, damage behavior, and corresponding mechanisms under various conditions. Our study demonstrates that higher impact energy results in increased structural stiffness, maximum temperature, and maximum voltage drop. Furthermore, heightened impact energy significantly influences the electrical resistance parameters within the internal resistance. We also examined the effects of State of Charge (SOC) and C-rates. The methodology and experimental findings will offer insights for enhancing the safety design, conducting risk assessments, and enabling the cascading utilization of energy storage systems based on LIBs.