In order to improve the survival ability of armored vehicles in the war, the protecting technology has been attached importance and developed completely by the world military powers. The paper presented the research state and protecting level of modern armor, and enumerated protecting furnishment of advanced armored vehicles, and summarized the research state and level of key protecting technologyarmor material. After introducing situation of armor protecting technology, taking the research content of U.S. and U.K., the development trend to the modern armor technologysynthesis protection system were analyzed.

Bottom protection，which is of great significance for improving the survivability of military vehicles and providing effective protection for crew，has become one of the research hotspots of the military vehicles. The research on bottom protection technique of military vehicles, the analysis of protection capability and optimization of structure based on numerical simulation, the evaluation of bottom protection capability, the bottom protection strategies and their applications, the technical measures and protection capability of typical vehicles are reviewed. The technical measures which include V-shape bottom hull, tabulate bottom floor made of new type material, interior structure of vehicle and crew restraintsystems are expatiated. The application and researchstatus of numerical simulation technology which is used to analyze the protection capability of military vehicle and optimize the bottom structure of vehicle are discussed. The research status of the effects of explosion shock on vehicle and its crew and the test evaluation of the bottom protection abilities of vehicle are analyzed. Simple local protection, locally added protection kits, special protection body with protection kits, and integrated protection solution are summed up. The bottom protection measures and capability of typical vehicles are analyzed. In addition，the future research direction andpriorities of bottom protection , and how to develop the protection capability of military vehicles are suggested.

The dynamic responses of projectile-borne electronic devices which are protected by encapsulating materialunder impact loading are studied through numerical simulation. A LS-DYNA user defined material subroutine is established according to the ZWT nonlinear viscoelastic model which is used for simulating the dynamic response of the encapsulating material in the projectile. The simulations of projectile penetration were performed by adjusting the controllable parameters of ZWT model, such as nonlinear elasticity modulus, low strain rate Maxwell elastic constant, high strain rate Maxwell elastic constant, high strain rate Maxwell relaxation time and material density. Thus the dynamic responses of projectile-borne electronic devices could be obtained from the numerical results. The research results show that the shock absorption and protection effects of the encapsulating materials are better when the values of nonlinear elasticity modulus, low strain rate Maxwell elastic constant, high strain rate Maxwell relaxation time and material density are decreased. Key

The core task of tank overall design is to get the best overall performance, minimum size and minimum weight without increasing the technical difficulty of parts. Relationship among the three main performances and the general dimensions of main battle tank (MBT) is analyzed by decomposing the specifications of firepower, mobility and protection. An optimization model is established for MBT's firepower, mobility and protection performance based on physical dimension. Restraining the height of tank is the key to coordinate the firepower, mobility and protection performance of tank. Approaches to restrain the height, width and length of tank are proposed.Key

Bullet-proof effects of composite materials and the protective capability of armored vests BPV- I、Ⅱ were investigated. Materials constituting the BPV- I、Ⅱ armored vests include ： aluminium alloy plates processed through quenching and ageing , high intensity polyamide fabric and trauma packs having special structures. The results showed that armored vest BPV- I can effectively prevent the penetration of 7. 62mm pistol bullets (Model 54，Made in China) fired at a distance of 3. 41m or more and that armored vest BPV- Ⅱ can be used to protect from shell fragments traversing at 422. 1m/s ?426. 8m/s in V50. Animal experiments proved that armored vests BPV- I、Ⅱ can avoid or remarkably attenuate non-penetrating trauma (NPT ) which has appeared puzzling for so many years because of the special design of the trauma pack.

In order to explore the interaction process and mechanism of bullet impacting a gelatin target with hard/ soft composite armor，the penetration of 7.62 mm bullet into composite armor and gelatin is numerically simulated using an FEA method，and the typical phenomena of impacting process and the dynamic response of gelatin target are analyzed. The simulation results show that the formation of the ceramic cone results from the compressive and tensile stress waves. The obvious segmentation and inflection points display on the curve of projectile acceleration. The acceleration reaches its maximum when the projectile penetrates into a ceramic faceplate. The second inflection point appears when the projectile penetrates into PE rear plate. The multi-peaks appear on the velocity curve of PE rear plate due to multiple interfaces on protection layer：When the projectile reaches the maximum acceleration，the first peak appears，and the first pressure peak appears on gelatin interface；the second peak appears when the projectile penetrates into PE rear plate. The propagation of pressure wave in gelatin presents the basic form of spherical wave， and the pressure peak propagation complies with the law of exponential decay.

In order to explore the protecting effect of venting structure with light and fragile material on gas explosion in building,the dynamic characteristics of venting structure under gas deflagration condition are analyzed according to the characteristics of internal gas deflagration overpressure and the protective theory of venting structure with light and fragile material. The vented explosion tests are performed by the gas explosion loading experimental equipment. The principles of using the venting structure with light and fragile material are proposed according to the current national design code of venting deflagration, which can be used in engineering protection of indoor gas explosion. The experimental verification methods of venting performance are also presented. The research results show that,for a venting structure with calcium silicate board, the opening dynamic pressure decreases with the increase in the duration time of gas deflagration pressure. Such venting structure should be used in the case of internal gas deflagration pressure with long duration time, and the opening dynamic pressure is regarded as its venting index and the venting performance test should be made. Key

It is inevitable to evaluate the aerodynamic heat and the ablation of thermal protection material for designing a hypersonic aircraft. A coupling method is presented for the calculation of aerodynamic heat, material ablation and transient temperature distribution. The method and program are validated by experimental data. The results indicate that the method has higher precision and efficiency. For a given trajectory, the aerodynamic heat, ablation performance of thermal protection layer and temperature filed are predicted by the coupling method. The proposed method can be used to calculate the ablation and temperature distribution in given operation conditions in design phase which is referable for the design of multi-layer thermal protection material for hypersonic aircrafts.

The metastable energetic materials were prepared for the space debris shield. Hypervelocity impact tests of PTFE/Al energetic material shield under the conditions of different areal densities, projectile diameters, and impact velocities were conducted by using two-stage light gas gun, and the high speed photographs and the signals from optical pyrometer during impacting were obtained. The analysis results show that the shock initiation of PTFE/Al energetic material shield occurs in the instant of hypervelocity impact, and the perforation process can be divided into three stages: shock detonation, fracture and deflagration, and zero reaction and crushing. A dimensionless empirical expression for perforation diameter of PTFE/Al shield is established based on the experimental results of hypervelocity impact. The effect of ambient temperature on the perforation characteristics of energetic material shield is investigated. Key

The electromagnetic driving technology can be used to simulate the high overload environment in the process of fuze launching, but it may stimulate magnetic field, which has negative effects on the test fuze. Thus, it is necessary to take the electromagnetic shielding measures for test fuze. The structure and working principle of the overload experiment device for fuze based on electromagnetic driving is introduced, and then the electromagnetic shielding cover for test fuze is designed. A simulation model is established for fuze overload experiment device based on electromagnetic driving, and then the intensity of magnetic field in fuze is analyzed at three occasions: without shielding cover, shielding cover made by aluminum, shielding cover made by aluminum and steel. The results show that the maximum magnetic field in fuze is 1.54 T, 0.17 T and 4.2×10^-5 T at the occasions mentioned above, respectively, which means that the shielding cover made by aluminum and steel has better shielding performance.

The multi-objective optimization of vehicle bottom structure under landmine explosion is a mass computation, strong-nonlinearity and high dimension multi-objective optimization problem. The protective vehicle structure response is simulated based on combination of LAE and FSI methods. The thickness and geometry parameters of vehicle bottom structure are screened with sensitivity analysis. A response surface is built by employing the experimental design and regression analysis. Eventually, the Pareto optimality, normal boundary intersection and multi-objective optimization genetic algorithms are applied to get the Pareto optimal front and an ideal solution which could give a comprehensive consideration of the contradiction between lightweight and protection capability.

The complex structure with high explosives may encounter an accidental fire event during storage, transportation, service or use. The objective of thermal protection design is that the highest temperature of explosives in the complex structure should not exceed 343 K(70 ℃) in 30 min under fire condition. Some thermal protection measures are presented by analyzing the main factors that affect the temperature rise of the explosives, which are to reduce the emissivity of shell surface, increase the thermal resistance in structural supports and use phase change materials for heat leading. The thermal protection effects of different schemes are computed and analyzed using FEM numerical analysis method. The results show that single measure can only reduce a local temperature, and the combining measures can satisfy the design requirement.

The fast rise time electromagnetic pulse (FREMP) is an important cause of damage to electronic equipment, and the PIN diode can effectively suppress electromagnetic pulse. In order to investigate the transient response of PIN diodes to FREMP, a time-domain equivalent circuit model based on PIN diodes is adopted. And the transient voltage characteristic of PIN diode circuit under the effect of FREMP is analyzed. Considering the parasitic components of PIN diodes and the bonding wire inductance, the whole physical structure of FREMP protection module is set up based on Butterworth low pass filter model. A FREMP protection module is realized. The measured insertion loss of protection module is lower than 0.38 dB in 1-250 MHz.At large signal condition with input square wave pulse of 4 000 V, the response time is less than 2 ns and the output level is lower than 30 V, which meets the protection requirement of FREMP. Key

The destruction forms of soft body armor penetrated by pistol cartridge are analyzed according to the penetration characteristics of pistol cartridge. A motion model of pistol cartridge penetrating into the gelatin target with soft body armor is established by introducing the fiber constitutive model and gelatin elastic model based on the material constitutive model of ultrahigh molecular weight polyethylene. The motion model is calculated by taking two pistol cartridges with the diameters of 9 mm and 5.8 mm as killer elements. At the same time, the numerical calculation and experimental verification are carried out, respectively. The calculated results are compared with the corresponding experimental results. The compa-rativeresult shows that the motion model can describe the motion of pistol cartridge penetrating into the gelatin target with soft body armor accurately.Key

To solve the issues of armored vehicle's protective area reduction, relatively complex installation process and so on, which are led by those conventional installation ways like bolting or rack supporting, a novel protective armor installation technology, called bonding technology, is presented. The kind and preparation technology of bonding agent are determined by the characteristics of installing structures. An optimal glued structure design for protective armor is proposed by studying the effects of different glued joint thickness and bonding areas on bonding strength. The bonding technology for installation is proved to be feasible and reliable through the simulated car broadband vibration test and the environmental extreme temperatures suitability assessment test. For the tests mentioned above, the bonding thickness is 2~3 mm; multi-point small area is glued ; the bearing capability is more than 3 MPa shear stress per square centimeter of bonding area; the bonding strength at extreme temperature from -50 ℃ to 70 ℃ is not less than 70% of corresponding strength at normal temperature. The results show that the two-component polyurethane adhesive is able to satisfy the dynamic broadband vibration requirement. Key

Aimed at the difficulty of the protection efficiency test system for the thermal

In order to study the moving and combustion conditions of powder, and the firing and flame propagation characteristics of the charge structure which has overload protection with ignition by detonation, an axial symmetry two dimension-two phase flow model of the layered charge structure using the ignition by detonation was set up based on the experimental study. The main parameters of ignition process were calculated using programming language, and some typical computed results were listed, such as pressure distribution pattern and solid phase void ratio distribution pattern. From the analysis of firing and flame propagation characteristics of the ignition process, it is concluded that the layered charge structure has nicer flame propagation characteristic.

A hierarchy conceptual model of the armor protection of engineer equipment was constructed and the method of analyzing and calculating its cost and effectiveness was proposed. Taking wheeled engineer equipment as an example, the cost-effectiveness analysis model was solved by the dynamic programming method. The sensitivity analysis of the calculated results indicates that it is necessary to enhance the multilayer protection construction to improve the survival probability of battlefield multi?layer protection of engineer equipment.

Well-developed bulletproof standards can not only correctly classify the protection grade of the bulletproof materials, but also offer efficient and practical guidance for commanders to choose different protective equipment when facing danger. Each country or an international organization establish their bulletproof standards according to their own particular circumstances, and therefore the protection levels vary from country to country. Several common bulletproof standards are summarized from four aspects: body armors, bulletproof helmets, armored vehicles and ballistic transparent materials. A side-by-side comparison of the projectile penetration energy for each protection level in different ballistic protection standards was conducted, and the bullet core and morphological structure of several of the commonly tested projectiles were compared and analyzed. Through the comparison and analysis of the commonly used bulletproof standards, the similarities and differences between domestic and foreign standards in terms of protection levels and the power of the tested projectiles were summarized. The results are expected to inspire and help researchers engaged in related industries to choose or improve their ballistic resistance standards.

In order to investigate the penetrating mechanism of a rifle bullet against the gelatin target with soft/hard composite armor in detail, a numerical model is established by using finite element analysis software ANSYS/LS-DYNA. The blunt impact phenomena during penetrating process and the transient response of gelatin and simulated using the proposed model, and are validated by experiment. The investigation results show that the kinetic energy of rifle bullet is mostly dissipated during the process of penetrating a ceramic plate. The temporary cavity in the gelatin presents in the basic form of ellipsoid, and the maximum depth and expansion velocity of cavity are 25.6 mm and 35.7 m/s, respectively. The pressure wave propagates in gelatin in the form of spherical wave with the largest peak pressure at the impact location, and the pressure amplitude decreases with the increase in travelling distance. The velocity of riflebullet decreases firstly while the absolute value of acceleration increases, and then they both gradually attenuate to 0. The failure of ceramic plate is mainly caused by the interaction of the compressive and tensile stresses. The numerical results are coincided with the experimental results. Key

In military applications, pulse forming network (PFN) needs to generate a flat-top current waveform by sequentially firing pulse forming units (PFUs)for the uniform acceleration of armature. However, when PFN works under this condition, a fly-wheel diode in PFN withstands a high reverse recovery voltage which may cause the failure of the fly-wheel diode. An approach in which the damage of semiconductor device can be eliminated by preventing from the reverse voltage is proposed through the theoretical analysis of reverse recovery process of diode. The mathematical expression of the proposed approach is derived from the equations of PFN circuit. This expression is used to calculate the parameters of a 600 kJ pulse power supply (PPS) constituted of 8 individual 75 kJ PFN modules. The PPS successfully generates an approximate flat-top current waveform without device damage. The test results show that the reverse recovery voltage can be eliminated by selecting proper circuit parameter. Key

The protective performance of foam aluminum-Al composite structures with different densities and thicknesses are investigated with conventional and improved split Hopkinson pressure bars (SHPB). The experimental results demonstrate that, when foam Aluminum is used as interlayer, the primary stress wave is divided into several stress waves. The time of stress wave arriving at a back plate is postponed, and the wave intensity decreases. The impact of stress wave decreases more clearly with the increase in thickness of interlayer. When foam aluminum-Al composite structure is used as faceplate, the pulse width broadens, the rising edge is improved, and the wave intensity reduces. At the same time, the foam aluminum-Al composite structures can absorb a large part of impact energy, which can be served as stress wave protective material. With the increase in thickness and relative density of the foam aluminum, the wave shaping effect is more significant. The wave intensity reduces, the rising slop becomes flat, however the stress wave pulse changes little. The influence of Al plate thickness on composite structure can be ignored.

The average velocity of space debris impacting on on-orbit spacecrafts is 10 km/ s, and 90% of them in low earth orbit are the middle and low density materials. The experiments of Mylar foil and Al flyer impacting on Al shield structure at 14 km/ s and about 9 km/ s, respectively, are done by electric gun and magnetic driving technology, and the damage results of Mylar foil and Al flyer impacting on shield structure are obtained. The results show that the debris cloud created by Al flyer impacting on Al shielding slab at about 9km/ s contains fluid state and even gas state, and the debris cloud created by Mylar foil impacting on Al shielding material at 14km/ s is solid state. For the Mylar foil flyer, the shielding effect of double shield structure is better than that of the single layer structure.

The mechanical properties of 30 kg/m³, 45 kg/m³ and 60 kg/m³ foamed polypropylene foams with different densities were obtained through material compression experiments, and the cranial response of a dummy under the protection of a functional gradient foam lining subjected to high velocity impact of gunshot was tested and simulated to analyze the cranial biomechanical response under the combination of homogeneous foam, positive and negative gradients, and concave and convex gradients. Based on this, a new type of bulletproof helmet capable of resisting rifle bullets was developed, and the protective effect of functionally graded foam lining in bulletproof helmet was studied. The local and overall energy absorption of the foam was analyzed. The results show that the energy absorption of the layered foam is mainly concentrated in the support layer near the head, accounting for 62.33% of the total energy absorption of the foam; the gradient structure has more significant protection effect than the homogeneous structure when the average density is the same, and the negative gradient is better than the positive gradient in protection; the convex gradient structure increases the energy absorption by at least 19.57% compared with other gradient structures while reducing the overall weight.

On the basis of a study on the mechanism of disturbing jet, mechanical model and engineering algorithm for a new type of protective armor disturbing the jet is put forward. Based on the basic hypothe?sis, the shock wave pressure emerging in the medium after the jet punctures the armor unit is estimated, while deformation of the armor unit plate and the jet are calculated. The calculated results accord well with the experimental results.

The liquid cabin with multi-layer protective structure plays an important role in defending the loadings of combined high-speed fragments and blast wave, which are usually due to the close-in explosion of a cast charge, and cause severe damage to the structure of liquid cabin. A new composite structure of liquid cabin is designed based on the dynamic response characteristics and failure mode of liquid cabin under the synergistic effect of high-speed fragments and blast wave. In order to investigate the anti-blast performance of composite liquid cabin, the traditional liquid cabin and newly designed composite liquid cabin are experimentally test under the blast load of cased charge. The fragment velocity, bulkhead deformation, perforation size, strain and shock wave pressure are obtained. The experimental data are analyzed and compared.It is found that, in the composite liquid cabin, the maximum deformations of front and rear bulkheads are decreased by 22.78% and 8.47%, respectively, the plastic strain is decreased by 30%, and the shock wave peak is decreased by 18.62%. Key

A sandwich structural coating with both fire resistance and thermal insulation properties is developed to improve the heat insulation/fire resistance performances of fuze and its packaging box. The use of coatings help to avoid the potential safety hazards caused by thermal stimulation. The slow and fast cook-off tests were made to analyze the thermal insulation performances of different coating structures. The results show that the fireproof coating used alone could not serve as a thermal insulation in the slow cook-off test. After applying an insulation outer coating layer, a strong protective layer could be formed under thermal stimulation. The temperature on the back side of steel plate is reduced by 32 ℃ in the slow cook-off test and 157 ℃ in fast cook-off test. The sandwich structural coating is applied to fuze shells and their packaging boxes. And it plays an important role in heat insulation/fire resistance performance. Compared with the unprotected specimen, the sandwich structural coatings could reduce the temperatures on the back side of steel plate by 21 ℃ and 33 ℃ in the slow cook-off test, and 117 ℃ and 105 ℃ in the fast cook-off test.

The porous foam aluminum alloy plate not only overcomes the shortcomings of the traditional protective structure such as heavy weight and inconvenient transportation, but also has the advantages of fatigue resistance and high specific strength. The lightweight and efficient anti-explosion protection materials are of great significance. The finite element analysis software LS-DYNA is used to numerically simulate the failure mode and protection performance of the sandwich composite plate under the combined action of shock wave and fragment, and analyze the effect of the foam aluminum sandwich structure on the deformation of the backboard under different arrangements. The results show that, at a detonation distance of 40 cm, the fragments will act on the target plate before the shock wave, and the fragment load strength is far greater than the shock wave load strength. When the arrangement of foam aluminum and fiber is “1 mm-thick aluminum alloy panel +10 mm-thick foam aluminum +10 mm-thick foam aluminum +10 mm-thick fiber +1 mm-thick aluminum alloy backplane”, the deformation displacement of the backboard is the smallest, and the total internal energy of the structure is the highest, which are 13.9 mm and 52.7 kJ, respectively. The overall deformation degree of the structure can be more effectively reduced and the energy generated by the panel deformation is absorbed under the working condition.

Facing the present status of camouflage and defence, crucial problems, existing in camou?flage net, smoke screen and decoy for use as ground targets，photoelectric defence, were analyzed. Aiming Jiigh-tech reconnaissance and detection, new demands for camouflage techniques including wide area camouflage defence, moving target defence, effective evaluation for photoelectric counter?measures and soldier’s camouflage clothing systems were pointed out. Some new concepts and tech?niques of camouflage defence, such as artificial fog without flame, IR thermal image, simulation de?coy, adaptive camouflage and bionic camouflage for the ground targets, were put forward.

To study the experimental correlativity of aerodynamic characteristics of intake and vent grilles in armored vehicles, the aerodynamic performance experiments of grille were carried out based on some typical structures. The aerodynamic and protective performances of air intake and vent grilles in China and U.S. military armored vehicles were comparatively analyzed. The results show that the protective performance of intake and vent grilles in U.S. military armored vehicles is better, but their aerodynamic performance is lower. The aim of grille design is to get the maximum protective capability with minimum throttling pressure loss and enough cooling air mass flux. The grille opening coefficient as a dimensionless parameter was proposed to evaluate the grille leaf structure. It is shown from analysis that the smaller opening coefficient means the stronger protective capability on the basis of certain grille material and leaf thickness.

All spacecrafts in low orbit are subject to hypervelocity impacts of meteoroids and space de-bris, which can in turn lead to its significant damage and catastrophic failure. An investigation into the impact damage characteristics has become an important problem for spacecraft protection design. The damage characteristics of the hypervelocity impact of Al-spheres to the rear wall of Al-Whipple shield were studied by the methods of experiment and numerical simulation. By comparing experiment data with numerical simulation results from AUTODYN—2D, it is found that the former is consistent with the latter fully. The impact damage law of rear wall of Al-Whipple snield by hypervelocity impact of Al-spheres with the projectile diameters, impact velocity and protection space was analyzed, and the leading factors which affect the damage of rear wall were proposed.

The multi-waveband infrared antireflection and protection film, on the ZnS dome which di- amter is 150 mm, the thicKness is 6 mm and the radius of curvature is larger, was plated by the method oi electronic beam vaccum deposition and ion-beam assisted deposition. The film average trans?missivity is above 90% in 3?5 μm and 92% in 8?10 μm, ana it can pass the mal-condition tests.

For severe damage to the lower limbs of vehicle occupant caused by the explosion shock below vehicle，a vehicle occupant lower limb protection device was designed by combining the flexible floor and the explosion-proof foot pad. The protective performance of the lower limb protection device and the influence of design parameters on the protective performance are studied based on vehicle explosive simulation，and a preferable design is determined. Static stiffness analysis of the preferable design is made to determine if it can provide sufficient support in daily use. Multi-objective optimization is performed for the structure of lower limb protection device to obtain the optimal design. The vehicle explosion simulation and test were carried out to verify this design. The results show that the occupant lower limb protection device can effectively reduce the impact to the lower limbs and significantly improve the protection ability of the lower limbs.

Blast-induced traumatic brain injury (BTBI) is the main form of injury for individual soldiers in the new war mode. Especially in the frequent terrorist attacks and explosion safety accidents in recent years, more and more civilians are suffering from such kind of trauma. So far, the domestic and foreign scholars have studied the brain injury caused by blast waves, but the injury mechanism, damage threshold, protection technology and injury assessment technology have not been clarified yet. Based on the extensive investigation on the latest research frontiers at home and abroad, the generation of blast waves, the types of brain injuries and its pathological characteristics, the research methods, the injury mechanism, the damage threshold and the protection methods are reviewed, focusing on analyzing the current research status and hot spots, the existing main problems and the future research direction.

To deal with the problem of blast shock wave causing traumatic brain injury, the protective performance of helmets based on blast shock waves was investigated. Combined with the pressure sensor and the head surrogate as the simulation target, the test method of protection against blast shock waves for different helmet structures and different positions in the helmet was developed. The pressure-time curves of the forehead, calvaria and back of head were obtained and the propagation principle of the blast shock wave on the surface of head with or without protection in the experiment were analyzed. The results showed that the helmets can effectively attenuated the peak overpressure of shock waves. The peak overpressure on the forehead could be attenuated from 352.57 kPa without helmet to 151.31 kPa with QGF-03 helmet and to 11.36 kPa with the full-face helmet. At the same time, the shock waves were prone to diffraction and superposition/convergence during the propagation in the head surrogate with helmet. The peak overpressure of the back of head with QGF-03 helmet and FAST helmet respectively increased by 50%-100% and 9% compared to the situation without helmet, and the duration of overpressure on head with helmet was significantly increased. The mask could significantly reduce the effect of the blast shock wave on the head and the peak overpressure of the shock wave on the forehead and face could be attenuated by 75%. The full-face helmet had the best protection effects and the peak overpressure on forehead, calvaria and back of head were respectively reduced by 90%, 87% and 80%. Moreover, the airtightness has a positive effect on protection against shock waves.

High-level explosive noise (HLEN) is a non-lethal damage accompanying explosions, which can directly damage one's auditory system. Using the mechanism analysis of the HLEN's awareness and propagation, explosive noise tests with different TNT mass are conducted to study the sound pressure (p_sp), sound pressure level (p_spl), propagation laws of free air burst (FAB), flexible explosive proof (FEP), and steel explosive proof (SEP). The HLEN protection performances of FEP and SEP are compared with that of FAB. The results show that the HLEN has typical characteristics of low frequency and high p_sp & p_spl. At 20 m to 40 m from the explosion center, the peak p_sp attenuations are about 50%, 52%, 48%, and the peak p_spl attenuations are about 5.7%, 4.7%, and 4.9% for FAB, FEP and SEP, respectively. The peak p_sp/p_spl travel time is equal, i.e., Δt_FAB=Δt_SEP=Δt_FEP=0.057 s. FEP can weaken the peak p_sp by 52% to 93.5% and reduce the peak p_spl by 4.8% to 9.1%. SEP can decrease the peak p_sp by 24.6% to 93% and reduce the peak p_spl by 1.4% to 6.9%. Human ear injuries are graded on a scale of Ⅰ to Ⅳ. With FAB, the injury is mainly grade Ⅳ and Ⅲ. With FEP, the injury is mainly grade Ⅲ and grade Ⅲ-Ⅱ. With SEP, the injury is mostly grade Ⅳ-Ⅲ and grade Ⅲ.

To evaluate the severity of damage to the human body caused by the blunt bullet or its penetrating through the body armor when the human target wears body armor, a digital model of human body wearing an armor is developed based on real human anatomy data. Then, the process of the bullet penetrating the protected gelatin target is captured by high-speed photography. The evolution data of the instantaneous space cavity inside the gelatin target is obtained. A simplified model of the instantaneous space cavity is established. The Abbreviated Injury Scale (AIS) method is used to evaluate tissue and organ damage. Damage scores of the corresponding parts of the human body under blunt hit and penetrating hit are obtained based on MAIS and NISS damage assessment algorithms, respectively. Besides, mortality rate is predicted. Human susceptibility assessment software is developed to obtain a severity score of damage caused to the human body when a small-caliber bullet bluntly hits and penetrates the body wearing an body armor at different speeds. When a small-caliber bullet hits the human chest with a body armor at 638 m/s, it causes blunt damage; the human injury score is MAIS=3, NISS=27, and the mortality prediction result is 12.88%. When a small-caliber bullet hits at 714 m/s, it penetrates the body armor and directly invades human tissue; the human injury score is MAIS=5, NISS=75, and the mortality prediction result is 97%.

Boron carbide ceramics are characterized by high strength, high wear resistance, high hardness, and low density, thus being the most ideal material for ceramic armor. This study reviews the application progress of ballistic-resistant boron carbide ceramics that meet the need for high-performance and lightweight human protective equipment. Factors affecting the ballistic performance of boron carbide ballistic ceramics are analyzed, the advantages and disadvantages of different sintering processes compared, and the sintering aid system and ceramic toughening technology approaches summarized. Lastly, the challenges and development needs facing the application of boron carbide ballistic ceramics are analyzed.

Aramid is widely used in the field of ballistic protection due to its light weight and high strength. In order to improve the trauma resistance of single-layer aramid fabrics, the surface modification methods of thermoplastic resin polyethylene (PE) and graphene nanoparticles (GR) are used innovatively to improve the ballistic performance of aramid fabrics. The trauma resistance and energy absorption of modified aramid fabrics with different mass ratios are studied based on the backface significance (BFS). The results show that both graphene and polyethylene modification methods can improve the blunt trauma resistance. The surface density of the modified fabric is increased slightly by polyethylene modification, but the resistance to blunt injury is significantly improved. Compared with pure aramid fabric, the bullet-proof ability and specific energy absorption value of 10% PE are increased by 18.0% and 30.8%, respectively. The increased rigidity of graphene-modified fabric increases its resistance to blunt injury at low speed, but the excessive inter-yarn friction weakens its resistance to blunt injury at high speed. 2% GR is the best ratio for graphene-modified fabric. In addition, the combined design of body armor with 2 layers of 10% PE and 13 layers of six layers of orthogonal UHMWPE unidrectional fabric is obtained through optimization and verification.

To explore the dynamic physical response of cranial brain under shock wave in warfare conditions, a physical model of protected/unprotected head surrogate impacted by shock wave from a soldier's rocket muzzle and intracranial pressure is developed. The pressure and evolution of different intracranial parts are analyzed. The intracranial pressure evolution for protected/unprotected head surrogates are compared. Under muzzle shock wave, the time-overpressure curve of unprotected intracranial pressure exhibits atypical shock wave characteristics. Unlike typical shock waves, the overpressure rises more slowly and lasts longer. The overpressure curve exhibits alternating oscillations of positive and negative pressure. The oscillation period is about 1 ms. The peak overpressure varies significantly in different intracranial parts. The counter shock side of the intracranial exhibits a significant negative pressure. The peak positive pressure on the counter shock side is nearly twice of that on the shock side, but the pressure impulses at different intracranial points are close to one another. Overpressure attenuation rates of different protected intracranial parts vary significantly. Compared with other intracranial parts, the overpressure attenuation rate of the counter shock side is highest. Moreover, the negative pressure effect on the counter shock side is weakened when covered with armor. The attenuation rate of the overpressure on the shock side is not obvious. The peak overpressure even increases in some parts with amor covered.