Topological optimization of ballistic protective structures through genetic algorithms in a vulnerability-driven environment

Reducing the vulnerability of a platform,i.e.,the risk of being affected by hostile objects,is of paramount importance in the design process of vehicles,especially aircraft.A simple and effective way to decrease vulnerability is to introduce protective structures to intercept and possibly stop threats.However,this type of solution can lead to a significant increase in weight,affecting the performance of the aircraft.For this reason,it is crucial to study possible solutions that allow reducing the vulnerability of the aircraft while containing the increase in structural weight.One possible strategy is to optimize the topology of protective solutions to find the optimal balance between vulnerability and the weight of the added structures.Among the many optimization techniques available in the literature for this purpose,multiobjective genetic algorithms stand out as promising tools.In this context,this work proposes the use of a in-house software for vulnerability calculation to guide the process of topology optimization through multi-objective genetic algorithms,aiming to simultaneously minimize the weight of protective structures and vulnerability.In addition to the use of the in-house software,which itself represents a novelty in the field of topology optimization of structures,the method incorporates a custom mutation function within the genetic algorithm,specifically developed using a graph-based approach to ensure the continuity of the generated structures.The tool developed for this work is capable of generating protections with optimized layouts considering two different types of impacting objects,namely bullets and fragments from detonating objects.The software outputs a set of non-dominated solutions describing different topologies that the user can choose from.

Study of the Ballistic Impact Behavior of Protective Multi-Layer Composite Armor

The abalone shell,a composite material whose cross-section is composed of inorganic and organic layers,has high strength and toughness.Inspired by the abalone shell,several multi-layer composite plates with different layer sequences and thicknesses are studied as bullet-proof material in this paper.To investigate the ballistic performance of this multi-layer structure,the complete characterization model and related material parameters of large deformation,failure and fracture ofAl_(2)O_(3)ceramics andCarbon Fiber Reinforced Polymer(CFRP)are studied.Then,3D finite element models of the proposed composite plates with different layer sequences and thicknesses impacted by a 12.7 mm armor-piercing incendiary(API)are built using Abaqus to predict failure.The simulation results show that the CFRP/Al2O3 ceramic/Ultrahigh Molecular Weight Polyethylene(UHMWPE)/CFRP(1 mm/4 mm/4 mm/1 mm)composite is the optimized stack of layers.The simulation results under specified layer sequence and thickness have a reasonable correlation with the experimental results and reflect the failure and fracture of the multi-layer composite protective armor.

Multi-Scale Design and Optimization of Composite Material Structure for Heavy-Duty Truck Protection Device

In this paper,to present a lightweight-developed front underrun protection device(FUPD)for heavy-duty trucks,plain weave carbon fiber reinforced plastic(CFRP)is used instead of the original high-strength steel.First,the mechanical and structural properties of plain carbon fiber composite anti-collision beams are comparatively analyzed from a multi-scale perspective.For studying the design capability of carbon fiber composite materials,we investigate the effects of TC-33 carbon fiber diameter(D),fiber yarn width(W)and height(H),and fiber yarn density(N)on the front underrun protective beam of carbon fiber compositematerials.Based on the investigation,a material-structure matching strategy suitable for the front underrun protective beam of heavy-duty trucks is proposed.Next,the composite material structure is optimized by applying size optimization and stack sequence optimization methods to obtain the higher performance carbon fiber composite front underrun protection beam of commercial vehicles.The results show that the fiber yarn height(H)has the greatest influence on the protective beam,and theH1matching scheme for the front underrun protective beamwith a carbon fiber composite structure exhibits superior performance.The proposed method achieves a weight reduction of 55.21% while still meeting regulatory requirements,which demonstrates its remarkable weight reduction effect.

Abrasion test of flexible protective materials on hydraulic structures

In this study, several kinds of flexible protective materials sprayed with polyurea elastomers （hereinafter referred to as polyurea elastomer protective material） were adopted to meet the abrasion resistance requirement of hydraulic structures, and their abrasion resistances against the water flow with suspended load or bed load were studied systematically through tests. Natural basalt stones were adopted as the abrasive for simulation of the abrasion effect of the water flow with bed load, and test results indicate that the basalt stone is suitable for use in the abrasion resistance test of the flexible protective material. The wear process of the polyurea elastomer protective material is stable, and the wear loss is linear with the time of abrasion. If the wear thickness is regarded as the abrasion resistance evaluation factor, the abrasion resistance of the 351 pure polyurea is about twice those of pure polyurea with a high level of hardness and aliphatic polyurea, and over five times that of high-performance abrasion-resistant concrete under the abrasion of the water flow with suspended load. It is also about 50 times that of high-performance abrasion-resistant concrete under the abrasion of the water flow with bed load. Overall, the abrasion resistance of pure polyurea presented a decreasing trend with increasing hardness. Pure polyurea with a Shore hardness of D30 has the best abrasion resistance, which is 60 to 70 times that of high-performance abrasion-resistant concrete under the abrasion of the water flow with bed load, and has been recommended, among the five kinds of pure polyurea materials with different hardness, in anti-abrasion protection of hydraulic structures.

The Use of Underground Metro Stations and Tunnels as Protective Structures in Case of Nuclear Emergencies

This paper discusses the use of Underground Metro stations and tunnels as protective structures in case of nuclear emergencies. Six lines are taken as a case study to investigate the use of their underground stations and tunnels. The research explains the structural design of Underground Metro and the necessary needs for hidden people inside Underground Metro used as shelters. The research investigates the calculations of the number of hidden persons inside Underground Metro used as shelters. A field study has been conducted to an Underground Metro station to detemaine the peaceful use and the emergency use of all basements of the station. Also, the field study aims to determine the existing spaces and the needed spaces of the Underground Metro station to dual--used as a nuclear shelter. Three Underground Metro stations have been selected and a field study has been conducted to determine the usages of these basements, the planning, general and design features for each one of them, and whether they can be used as protective structures for citizens in emergencies. These basements were compared for their protective factors. Also, their capacities for sheltering were calculated.

Effects of Protective Structures in Morpho-Sedimentological Changes： A Case Study of Rufisque＇s Coast, Petite C6te, Senegal

Protective structures, built in the 1980＇s in order to reduce or stop coastal erosion in Rufisque, involved a modification of the coastal morpho-sedimentary landscape and have intensified the coastal dynamics. The diachronic study of beach profiles, before and after the seawalls construction showed that these protective structures accentuated the coastal erosion, with more important sedimentary deficits at the ends of the structures. Today, the Rufisque coast is characterized by a set of sedimentary cells whose morphological evolution and annual sedimentary dynamics are controlled by seasonal forcing： sedimentary deposits in dry season and erosion in wet season. However, this alternation of deposits and erosion phase shows spatiotemporal disparities. These disparities are very marked between a northwestern area characterized by concave profiles and a southeastern area （the bay of Rufisque） characterized by convex profiles and a much more important sedimentary deficit. The results also showed that these methods of shoreline protection are not durable measurements （degradation of the structures） and have exacerbated the vulnerability to coastal erosion as well as those of the coastal populations.

Effect of TYLCV Infection on Leaf Anatomical Structure and Protective Enzyme System of Tomato

[Objective] The aim was to study the effect of tomato yellow leaf curl virus （TYLCV） infection on leaf anatomical structure and protective enzyme system of tomato. [Method] The anatomical structure of infected and healthy leaves of tomato were observed and compared by using paraffin section method. The activity changes of SOD, POD and CAT in the infected leaves of tomato were determined. [ Result] The results revealed that there were some differences in anatomical structure between healthy and infected leaves. Some cells of infected leaves were damaged so that the leaves curled and became yellow, which affected the normal function of organs. Compared with control, enzyme activities in the tomato plants infected by TYLCV were enhanced at the early periods and higher than that in control, then started to decline at the middle and late periods but lower than that in control.[ Conclusion] After infection by TYLCV, the leaf anatomical structure of tomato was changed greatly and the protective enzyme system was damaged severely, and affected the normal physJological metabolic functions of tissues and organs in tomato in further.

The personal protective equipment(PPE)based on individual combat:A systematic review and trend analysis

With the development of ordnance technology,the survival and safety of individual combatants in hightech warfare are under serious threat,and the Personal Protective Equipment(PPE),as an important guarantee to reduce casualties and maintain military combat effectiveness,is widely developed.This paper systematically reviewed various PPE based on individual combat through literature research and comprehensive discussion,and introduced in detail the latest application progress of PPE in terms of material and technology from three aspects:individual integrated protection system,traditional protection equipment,and intelligent protection equipment,respectively,and discussed in depth the functional improvement and optimization status brought by advanced technology for PPE,focusing on the achievements of individual equipment technology application.Finally,the problems and technical bottlenecks in the development of PPE were analyzed and summarized,and the development trend of PPE were pointed out.The results of the review will provide a forward-looking reference for the current development of individual PPE,and are important guidance for the design and technological innovation of advanced equipment based on the future technological battlefield.

Structural Design and Protective Methods for the 100 kW Shoreline Wave Power Station

The structural design and protective methods for the 100 kW shoreline wave power station in China are described in detail. The proper structural type is designed for effective minimization of wave loads and bending stress. Various protective devices are adopted to protect the station in the extreme conditions against excessive power of airflow, excessive torsion of the shaft, over-pressure of the chamber, over-speed of rotation, power failure, and so on. It turns out that the structural design and protective methods for the 100 kW shoreline wave power station are successful.

Design and test of a protective structure for the double vertical explosive welding of large titanium/steel plate

A comprehensive protective structure with rigidity and flexibility was put forward and designed in view of the quality and safety problems for the double vertical explosive welding of large titanium/steel cladding plate.The movement speed and displacement of the protective structure was calculated by establishing its physics model.The dynamics and stabilization properties were analyzed,and the protective structure parameters were optimized and devised.The comprehensive protective structure,which is composed of rigidity unit and flexibility wall,can bear the impact of detonation wave and the high-speed movement of the cladding plate.There are no damage and deformation in the protective structure and the cladding plate.The protective structure can be used many times.The bonding rate of the Ti/steel plate obtained was nearly 100%,and there is no deformation,surface cracks,and big wave and micro-defects.Therefore,the protective problems of the double vertical explosive welding can be solved effectively by the protective structure.

Experimental study on anti-penetration mechanism of bolted composite protective structure with limited span under impact of low-velocity projectile

In order to study the influence of the bolt joint mode on low-velocity projectiles penetrating the composite protective structure,two bolt joint models which connect the composite target to the fixed frame were designed,the ballistic test of the bolted composite protective structure with limited span was carried out,and the bearing and failure characteristics of the bolted region,as well as the energy dissipation of each part of the structure,were analyzed.The results show that in the condition of lowvelocity impact,there are three failure modes for the bolted composite protective structure subjected to projectile penetration,including failure of the impact point of the composite target,failure of protective structure connecting components and failure of the holes in the bolted region of the composite target;the failure mode of bolt holes in the bolted region has a great influence on the protection performance,and the allowable value of the bearing capacity of the bolted region depends on the sum of the minimum failure load in the failure modes and the friction force;shear-out failure occurring in the bolt holes in the bolted region exerts the greatest effect on ballistic performance,which should be avoided;When simultaneous failure occurs in the bolted region and the free deformation region of the composite protective structure,the energy absorption per unit surface density of the composite protective structure reaches the maximum,which can give full play to its anti-penetration efficiency.

Seismic protection of frame structures via semi-active control:modeling and implementation issues

Theoretical and practical issues concerning the multi-faceted task of mitigating the latero-torsional seismic response of a prototypal frame structure with asymmetric mass distribution are approached, Chevron braces with embedded magnetorheological dampers acting on the interstory drift are used to ensure additional energy dissipation. The semi-active control strategy employed to govern the modification of the damper characteristics via feedback is based on the selection of optimal forces according to a H2/LQG criterion, with respect to which the actual forces are regulated by a clipped-optimal logic. A dynamic observer is used to estimate the state through a non-collocated placement of the acceleration sensors. Several aspects to be addressed throughout the complex process including the design, modelization, and implementation phases of semi-active protection systems are discussed. Finally, experimental results obtained to mitigate the motion induced by ground excitation in a large-scale laboratory prototype, simulating the seismic response of a two-story building, are summarized.

Editorial: Special subject on the mechanical behavior of thermal protection materials and structures

The thermal protection materials and structures are widely used in hypersonic vehicles for the purpose of thermal insulation, and their mechanical behavior is one of the key issues in design and manufacture of hypersonic vehicles. It is our great pleasure to present the seven papers in this special subject of Theoretical ＆ Applied Mechanics Letters （TAML） and introduce the recent progresses on the mechanical behavior of thermal protection materials and structures by the authors.

Fibre Optic Protection System for Concrete Structures

The design concepts, modelling and implementation of various fibre optic sensor protection systems for development in concrete structures were investigated. Design concepts and on-site requirements for surface-mounted and embedded optical fibre sensor in concrete were addressed. Finite element （FE） modelling of selected sensor protection systems in strain-transfer efficiency from the structure to the sensing region was also studied. And experimental validation of specified sensor protection system was reported. Results obtained indicate that the protection system for the sensors performs adequately in concrete environment and there is very good correlation between results obtained by the protected fibre optic sensors and conventional electrical resistance strain gauges.

Thermal and Structural Behaviour of Offshore Structures with Passive Fire Protection

In offshore structures,hydrocarbon fires cause the structure to loose its rigidity rapidly and this leads to structural integrity and stability problems.The Passive Fire Protection(PFP)system slows the transfer rate of fire heat and helps to prevent the collapse of structures and human losses.The vital design factors are decided in the detailed design stage.The determined design thickness must be accurately applied in the fabrication yard.However,there are many cases that the PFP is overused because of various reasons.This excessive application of the PFP is an unavoidable problem.Several studies have been conducted on the efficient application and optimal design of the PFP.However,the strength of the PFP has not been considered.In addition,research studies on the correlation between the thickness of the PFP and the structural behaviour are not widely available.Therefore,this study attempts to analyse the thermal and mechanical effects of the PFP on the structure when it is applied to the structural member.In particular,it is intended to determine the change in the behaviour of the structural member as the thickness of the PFP increases.

A Review of Current Researches on Blast Load Effects on Building Structures in China

The damages of building structures subjected to multifarious explosions cause huge losses of lives and property. It is the reason why the blast resistance and explosion protection of building structures become an important research topic in the civil engineering field all over the world. This paper provides an overview of the research work in China on blast loads effect on building structures. It includes modeling blast shock wave propagation and their effects, the dynamic responses of various building structures under blast loads and the measures to strengthen the building structures against blast loads. The paper also discusses the achievements and further work that needs be done for a better understanding of the blast loads' effects on building structures, and for deriving effective and economic techniques to design new or to strengthen existing structures.

Comparative analysis of structural characteristics and cardiomyocyte protective effects of glucomannan extracted from Bletilla striata using varied methods

Doxorubicin(DOX)is a widely employed tumor therapy,yet its substantial toxic side effects pose a considerable challenge.Bletilla striata has demonstrated efficacy in preventing and treating these toxic side effects in clinical practice,with polysaccharides identified as the principal active component.In the present study,16 fractions of B.striata polysaccharides(BsPs)were extracted using diverse methods,including hot-water extraction(HWE),ultrasonic-assisted extraction(UAE),enzyme-assisted extraction(EAE),dilute acid-water extraction(ACWE),and dilute alkali-water extraction(ALWE).These extractions were subsequently precipitated at final ethanol concentrations of 80%and 95%,respectively.The investigation encompassed yields,total carbohydrate content(TCC),total protein content(TPC),preliminary structural properties,and anti-DOX myocardial cytotoxic activity.Results indicated that the extraction method significantly influenced the physicochemical properties,associated functional properties,and anti-DOX myocardial cytotoxic activity of BsPs.HWE and UAE yielded higher BsPs quantities.The relative molecular weight(RMW)distribution of BsPs differed notably between HWE or UAE,EAE,ACWE,and ALWE.The RMW of primary BsPs obtained from HWE and UAE(1.9×10^(7)-1.7×10^(7) Da)exceeded that from EAE(7.5×10^(3)-2.8×10^(4) Da)and ALWE(5.1×10^(4)-1.7×10^(4) Da),with smaller molecular weights primarily precipitated by higher ethanol concentrations.BsPs were composed of Man and Glu,with partial fractions containing small amounts of Gal or Ara,displaying varying molar ratios.Notably,BsPs from ACWE exhibited the most significant structural differences,lacking 1,4-α-D-Glcp and a triple-helical structure.Furthermore,BsPs obtained from HWE,UAE,and EAE demonstrated heightened anti-DOX myocardial cytotoxic activity compared to other methods.This study underscored the influence of extraction methods on BsPs’structure and myocardial protective activity,offering a foundation for exploring structural diversity and employing specific extraction methods to extract polysaccharides with robust myocardial protective properties efficiently.

Root structure of slope protection plants in a high-grade highway

Root length and root length density of Lespedeza bicolor,Amorpha fruticosa,and Sea buckthorn were investigated in a country highway-TongSan highway（Tongjiang to Sanya） in Heilongjiang Province,China.The root lengths were divided into five root orders according to Pregizter sequence classification method.Results show that sea buckthorn roots are dominated by coarse roots in the horizontal growth,while L.bicolor has a large proportion of fine roots in vertical conical growth and A.fruticosa is in depth growth.Root length density of L.bicolor in all the root sequences is higher than that of sea buckthorn and A.fruticosa.On the basis of the root structure,it is inferred that L.bicolor roots mainly absorb the surface soil moisture for its normal growth;in contrast,A.fruticosa has good uptake ability to deep soil water.The root structure of sea buckthorn implies that it has a strong drought resistance.

Reaction degree of composition B explosive with multi-layered compound structure protection subjected to detonation loading

The explosive reaction degree and protection from explosions are concerns in the military field.In this work,the reaction degree of the composition B explosive was investigated experimentally.Multi-layered compound structures were used as barriers to weaken the blast loads.A comprehensive experiment using a high-speed camera and image processing techniques,side witness plates,and bottom witness plates was presented.Using the experimental fragment velocities,fragment piercing patterns,and damage characteristics,the reaction degree of the explosive impeded by different multi-layered compound structures could be precisely differentiated.Reaction parameters of the explosive obstructed by compound structures were obtained by theoretical analysis and numerical simulations.Unlike the common method in which the explosive reaction degree is only distinguished based on the initial pressure amplitude transmitted into the explosive,a following shock wave reflected from the side steel casing was also considered.Different detonation growth paths in the explosive formed.Therefore,all these shock wave propagation characteristics must be considered to analyze the explosive response impeded by compound structures.

A SIMULTANEOUS APPROACH TO WATER - RESOURCE PROTECTION AND ECONOMIC STRUCTURAL ADJUSTMENT—A Case Study of Guanzhong Region in the Huanghe River Basin, China

A regional multiple objective water resource and economic optimization model was developed using a quantitative method of systematic analysis. Input to the model includes indexes of economic structure and development, water resource utilization, wastewater and pollutant discharge, and investment in wastewater treatment. The model, which consists of production structure and industrial structure optimization modules, was applied to the Guanzhong region in the middle reaches of the Huanghe (Yellow) River basin in China. By evaluating several alternative production and industrialization schemes, the modal indicate that water pollution will get worsen though wastewater treatment improves if the economy continues to develop at the planned speed without structural adjustment. However, the results also show that not only economic goals but also water resource protection and pollution control targets can be achieved under an alternative, recommended production and industrial structure. This example illustrates that economic development and environmental protection can be improved coordinately by the regional multiple objective water resource and economic optimization model. It provides an operable approach to the simultaneous sustained development of water resources and economic growth.