• Damage Tolerance Criterion (DTC) established for overload damage evaluation • High amplitude narrow pulses affect tolerance sharply while wide pulses stabilize it • Impulse-equivalence framework enables damage assessment for arbitrary shock pulses Projectile-borne electronics are essential components for precision-guided munitions. However, they are subjected to a complex overload environment characterized by high-frequency vibrations, high temperatures, and high pressures during launch. Evaluating overload damage presents a significant challenge. Consequently, this study aims to establish a damage tolerance criterion for projectile-borne electronics in high-g extreme environments using impact overload tests and high-precision numerical simulations. Initially, an impact overload test device was designed and implemented, considering the guidance segment and chamber firing characteristics, to ascertain the overload damage characteristics of projectile-borne electronics. Subsequently, a simulation model incorporating projectile-borne electronics was established and validated to identify the most vulnerable regions and critical overload responses under various conditions. Based on the simulation data, the overload damage tolerance curve was established using a power function regression fitting method. Leveraging the concept of impulse equivalence, the damage tolerance criterion for the high-g extreme environment was formulated. The criterion’s accuracy and practicality were further verified through experimental damage results of electronic components. This study provides a practical design foundation for the anti-high-overload design of projectile-borne electronics.

• We investigate the dynamic behavior of nest–like structures under uniaxial impact. • A confined deformation zone forms near the loading end during the impact. • We proposed a rigid–perfectly–plastic–locking (R–P–P–L) shock model, to quantitatively predict how the confined propagates. Inspired by natural bird nests, nest-like structures consist of randomly packed slender particles confined within a container. This study investigates the dynamic behavior of nest-like structures by finite element simulation and a shock model. Under dynamic impact conditions, the nest-like structures exhibit distinct mechanisms compared to quasistatic loading. A confined deformation zone with nearly uniform stress forms near the loading end. This zone propagates steadily into the undeformed region at a constant velocity. Notably, the expansion speed exceeds the loading rate but remains significantly slower than the stress wave speed in solid material. We proposed a rigid-perfectly plastic-locking (R-P-P-L) shock model to quantitatively establish how initial conditions govern two critical dynamic responses: the stress in the confined zone and the expansion velocity of the confined zone. These dynamic characteristics of nest-like structures demonstrate their potential for impact resistance.

• Filling material type significantly affects PMMA joint crack propagation, with air-filled joints producing multi-cracks and silicone/epoxy-filled joints generating single cracks at different positions. • Quasi-static loading leads to more pre-crack energy accumulation and a higher initial stress intensity factor than dynamic loading, and silicone/epoxy-filled specimens show longer energy recovery time than air-filled ones. • Under dynamic loading, PMMA joint length positively correlates with crack initiation and propagation time, and material hardening parameter and fractal dimension also exert notable impacts on PMMA fracture. This study employed a dynamic caustics system integrated with a Hopkinson pressure bar, Schlieren optics, and a high-speed camera to investigate how joint span and shape affect crack initiation and propagation. First, crack penetration into joints with different spans (10 mm, 30 mm, 50 mm) and different shapes (“u” and “n”) was visualized. Then, crack-tip stress intensity factors and propagation velocity were measured by high-speed caustics patterns. Finally, fractal dimensions of crack trajectories were obtained to quantitatively evaluate the complexity of the crack layout. Based on loading time, the crack behavior is divided into 4 phases: first precrack initiation, propagation toward the joint, secondary initiation from the joint and final propagation toward the boundary. Since the phase 1 duration increases with span, crack initiation from precracks clearly depends on span length. In phases 2 and 3, reflected waves occur from the joint interface; furthermore, they are confirmed to be Rayleigh waves through wave velocity. Meanwhile, the reflected Rayleigh waves from the “n”-shaped joint have a significant effect on crack propagation in phase 2. In phase 4, crack trajectories initiating from joint ends are heavily influenced by joint span, which is associated with crack interaction. Furthermore, different opening orientations (“u” and “n”) of arc-shaped joints have different effects on crack behavior. The “u”-shaped joint exhibits crack behavior similar to that of same-span line-shaped joints. The “n”-shaped joint demonstrates a strong fracture resistance. This work advances the understanding of fracture resistance as influenced by joint span and shape variations.

• Annealing after deformation is carried out in order to stabilize formed submicrocrystalline structure, to isolate dispersed strengthening particles and to increase electrical conductivity. • Optimization of copper heat-strengthened alloys deformation and heat treatment technology is a key factor in obtaining metals with an optimal combination of properties. This paper presents a new technology for copper wire processing. This technology involves deforming the wire in a rotating equal-channel stepped matrix, after which the workpiece is subjected to a drawing operation. As a result of the deformation of the copper alloy wire via this technology and subsequent annealing at 400°C, a gradient microstructure with improved mechanical properties was obtained. Annealing after deformation is carried out to stabilize the formed submicrocrystalline structure, isolate dispersed strengthening particles and increase the electrical conductivity. The surface zone is crushed to 400 nm, and the intermediate zone is crushed to 2 μm. Then, the grain size increases further toward the central part of the wire and is 22 μm. The generation of a gradient-symmetrical microstructure was confirmed via microhardness tests. Thus, our method, which combines twisting in a rotating matrix and drawing, is a promising tool for obtaining materials with improved mechanical properties. It allows reducing drawing forces, obtaining a gradient structure of the material and increasing its plasticity.