Silicone rubber is extensively used in engineering applications due to its toughness and impact resistance; however, traditional characterisation methods fail to capture its nonlinear deformation characterisation and triaxial mechanical behaviour. To address this, we derived a constitutive model within the framework of continuum mechanics that assumes a condition of near incompressibility and conducted uniaxial, planar, and equibiaxial tension tests to fit the model parameters. Through systematic analysis of triaxial mechanical responses under these three loading modes, we determined the material’s nonlinear large-deformation behaviour and sensitivity to the biaxiality ratio. Comparative analyses with classical hyperelastic models show that the proposed model achieves a good balance between the number of parameters and fitting accuracy. After the parameter-fitting process, we performed finite element simulations of the three loading modes. The simulation results show good agreement with experimental data in terms of deformation patterns and stress–strain curves. This study provides a novel theoretical tool for evaluating the mechanical properties and structural designs of soft materials.

Strikes can potentially damage the aeronautics structures and result in flight failure. In this research, damage mechanisms of low-velocity, high-energy blunt impact over a large area on the composite fuselage panel are predicted using the Finite Element Method (FEM) in Pam-Crash, using explicit dynamic methods to capture transient responses during impact events. The Ladevèze fabric model within Pam-Crash has been implemented to model the impact-induced damage. Two different impactors, i.e., rigid and soft bodies, are studied in this research. The panel structure is located at the center fuselage section of a narrow-body aircraft. Representative boundary conditions were applied to the unreinforced regions of the large panel to represent its sense of service. According to the simulations, the damage in the case of deformable-body impact is less than in the other case. This is mainly because of the mutability characteristic of the deformable impactor, which distributes the load over a wider area. Under both impact cases, damage tends to initiate in the skin and propagate towards the internal supporting structures. Interlaminar failure preferentially occurs in regions of high tensile strain concentration, while structural fracture is prone to occur in regions of high compressive stress concentration. Furthermore, the damage pattern is found to be barely visible, showing no significant surface indications but extensive internal delamination and matrix cracking, substantially compromising the residual load-bearing capacity. Through the rigid and deformable impact-induced damage analysis on composite fuselage panels, the present study elucidates impact damage mechanisms and quantifies damage distribution patterns. These findings provide critical guidance for crashworthy design and precision inspection of the center fuselage section. The derived impact response characteristics and damage mechanisms provide a basis and data support for subsequent research, including the physical experiments.

Polyurethane materials are widely used in the windshield interlayer of aircraft and other vehicles due to their excellent mechanical properties, i.e., high toughness and impact resistance. Their adhesive properties effectively mitigate secondary debris from glass shattering after high-speed impacts from foreign objects, thereby improving the windshield’s structural safety. Based on engineering experience, high-temperature bird strike conditions are the most severe for windshields; therefore, this study investigates the dynamic mechanical behaviour of polyurethane materials at 45°C. Through static mechanical tests with varying triaxialities and dynamic tensile tests at 45°C, a viscoelastic constitutive model was developed to characterise the material’s dynamic mechanical behaviour. The results show that the fitted viscoelastic constitutive model has high reliability.

Elastomer polymers exhibit significant stress softening phenomena under cyclic loading, which is commonly observed in engineering applications such as sealants and dampers, directly affecting material service performance and lifespan. Previous studies have primarily focused on the loading history dependence of stress softening, while the understanding of its time-dependent behaviour remains relatively limited. This research employs silicone rubber as the material to confirm its characteristic stress softening behaviour through cyclic loading-unloading experiments, effectively excluding the interference of viscoelastic effects. Based on this framework, stress-recovery and stress-relaxation experiments were systematically conducted to elucidate the temporal evolution patterns of stress softening behaviour. Experimental results demonstrate that stress softening exhibits time correlation, manifested as partial recovery of softening effects after rest periods in materials like silicone rubber. During stress relaxation tests, this material undergoes gradually decreasing stress levels with minimal viscoelastic characteristics. These findings provide novel insights into the fundamental mechanisms of stress softening behaviour. This study enhances the understanding of nonequilibrium mechanical behaviours in elastomer polymers.

Elastomeric polymers, with their excellent flexibility and high elasticity, are widely used in various engineering fields, including vibration damping, sealing, and flexible structures. Under complex loading conditions, their mechanical response typically exhibits pronounced viscoelasticity and stress-softening phenomena. Although both phenomena demonstrate stress-strain hysteresis characteristics, their physical mechanisms are fundamentally different. Current research often confuses these two phenomena, lacking systematic experimental identification and mechanistic differentiation. This study effectively separated the effects of viscoelasticity and stress softening by preparing typical rubber-like polymer samples and combining them with special cyclic loading-unloading experiments. The results show that the viscoelastic response is strain rate-dependent and recoverable; while stress softening mainly occurs in the initial loading and unloading stage, exhibiting loading history dependence and irreversibility. Based on experimental data, this study further explains the origin differences of the two behaviours from the perspective of microstructural evolution. The research results provide an experimental basis for constitutive modelling of rubber-like materials and have guiding significance for the design optimisation and life prediction of key components such as rubber vibration dampers and seals in engineering structures.

Polymer interlayers have been widely applied in windshields due to their impact resistance. As an interlayer material, Polyurethane (PU) can effectively buffer the differential deformation between glass layers, prevent instantaneous failure of the system, and avoid spalling injuries to pilots caused by glass fragments. Considering the severity of bird-strike events, this research focuses on exploring the dynamic mechanical performance of PU across a wide temperature range. This research proposes a decoupling mechanism and develops a hyper-viscoelastic model of PU. The fitting results demonstrate the high reliability of this model across a broad temperature spectrum.