Defense Engineering Research Articles

Experimental and Three-dimensional Mesoscopic Simulation Study on Coral Aggregate Seawater Concrete with Dynamic Direct Tensile Technology

The dynamic tensile properties of coral aggregate seawater concrete (CASC) play a substantial role in reef engineering and marine military defense engineering applications. CASC and sisal fiber coral aggregate seawater concrete (SFCASC) with sisal fiber content of 3 kg/m3 were prepared in this study. The dynamic tensile test under high strain rate was carried out using the Split Hopkinson Tension Bar (SHTB) technology. The 3D mesoscopic concrete model was used to simulate the dynamic tensile properties of CASC. And the destruction mechanism of CASC was revealed from the experiment and meso-simulation. The results showed that sisal fiber contributes little to the DIF growth of strength and fracture energy under dynamic tensile loading, and the cracks in the common concrete bypass the aggregate, while the cracks in the CASC develop through the aggregate due to the micro pumping effect of the aggregate and the characteristics of brittle and porous coral. The DIF calculation models of the tensile strength and fracture energy were established according to the test results. The numerical model established by the mesoscopic method can accurately predict the mechanical properties of CASC under impact load. The simulated crack appeared in the middle of the specimen, which was consistent with the failure pattern obtained by the test, and further verified the accuracy of the 3D meso model for simulating the impact performance of CASC.

Individual Liability and the Development of Defensive Engineering in Professional Practice

AbstractRecent years have witnessed increased individual sanctions for engineers in the event of a major failure such as the Deepwater Horizon blowout. The medical profession experienced a similar ...

Research progress of anti-penetration yaw technology for concrete protective structures

Concrete protective structure is an important part of national defense engineering. It is of great significance to study its development status and penetration mechanism. This article summarizes the recent research status of concrete protection yaw technology, and summarizes the existing yaw technology by distinguishing materials and structural asymmetry. The anti-penetration and yaw mechanism of the protective structure is summarized: The first is to analyze the effects of warhead shape and material, the incident state of the projectile, the configuration of the reinforcement and the aggregate parameters on the resistance to the penetration and yaw. The second is angle of attack effect and contact theory; the third is to analyze the role of numerical simulation in the research of yaw technology; and put forward suggestions for future research work.

Risk Assessment and Management of National Defense Engineering Construction Based on HHM-RFRM

The risk of the national defense engineering construction is generated under the influence of various factors such as personnel, mechanical equipment and environment. This paper uses Hierarchical Holographic Modeling ideas and Risk Filtering, Rating and Management theory(HHM-RFRM) research method, constructs a risk measurement model for multi-dimensional construction risk scenarios by using repeatedly iterative methods; combined with Bayes’ theorem, filters and grades multi-dimensional construction risk scenarios qualitatively and quantitatively, and finally takes a national defense engineering construction as an example to verify the practicability of the proposed model and the feasibility of the method. The evaluation method overcomes the limitations of the traditional risk assessment method with a single perspective and a single model, and better expresses the authenticity of the risk and the complexity of the system, and provides a theoretical basis for the construction risk management and decision-making of the position and practical reference.

Metallurgy and machine building - traditions and innovations

In December of 2019, CNIITMASH celebrates the 90th anniversary. Through all these years, the CNIITMASH team takes and active participation in the development of national machine building, creating new machines and technological processes, doing fundamental research necessary to solve the problems of equipment designing, developing new steel grades and dealing with heat treatment modes to improve materials properties. The information on the stages of formation and development of the Institute presented. Scientific and technical achievements in such areas as creation of fundamentally new technological directions, materials with special properties and equipment for their manufacturing; elaboration of technologies and materials for brand new equipment samples for power and heavy engineering; development of special electro-metallurgy and foundry technologies for nuclear and power machine building etc. The contribution of CNIITMASH into to gear engineering for purposes of heavy machine building, power, transport, defense and other engineering sectors.

High-resolution helicopter geophysics in support of a Defence engineering project

project at an Australian RAAF base in support of a base expansion project. The purpose was to identify, document and if possible, mitigate potential sources of groundwater contamination and related pathways. The two boom-mounted airborne systems that were deployed were designed for detection and mapping of shallow buried metals. An area of 1740ha was s urveyed with a combination of magnetic gradiometer and time-domain electromagnetic induction. Approximately 1230ha of this was flown at low altitude (1-3m) with a 16-sensor vertical gradient system (VG-16). The remaining area was flown at higher altitudes due to vegetative cover. Areas of special interest totaling 290ha were followed up with an 8-receiver low altitude electromagnetic survey (TEM-8). Ground follow-up with excavation was then conducted on a selection of anomalies to identify their causative sources.

The Future Exchange of Digital Engineering Data and Models: an Enterprise Systems Analysis

In the process of the Defense Department’s Digital Engineering transformation, a series of innovation programs and challenges will need to be sponsored that lead to an evolutionary transformation of the defense engineering and acquisition enterprise. The DoD should pursue a set of development/investment opportunities in the areas that have the most impact on short and long term transformative change. A critical innovation impact area is the process of digital information exchange. In a study to address this transformation process, we used the systemigram method to create a conceptual model of a likely future digital information exchange process emerging from the department’s strategy. The systemigram process creates a holistic view of the outcomes of enterprise change for the stakeholders, who usually only have a small part of the system in their mental models. The systemigram was presented and validated at a Digital Information Exchange Working Group meeting attended by a broad group of government and industry stakeholders. The meeting and accompanying discussions started a process of community agreement on terminology and innovation needs surrounding the exchange of digital system information. This paper presents that systemigram model and discusses the outcomes of the community discussion. For those interested in the future information exchange process, the systemigram provides a first look at the end-to-end business process that should emerge from DoD Digital Engineering initiatives and strategy. For innovators, the systemigram provides a number of opportunity spaces that might be pursued.

3D meso-mechanical modelling of impact response of reinforced concrete beams

An understanding of the response and failure of reinforced concrete structures subjected to impact loadings is of great importance in safety calculations and assessment in civil as well as defence engineering. In this paper, a numerical study is performed on the impact response of reinforced concrete beams by a newly proposed 3D meso-mechanical model together with a recently developed computational dynamic constitutive model for concrete. In the 3D meso-mechanical model, concrete is considered as a three-phase composite material consisting of mortar matrix, coarse aggregates and interfacial transition zone (ITZ layers). The constitutive model for concrete takes into account pressure dependency, shear damage, tensile softening, Lode effect and strain rate effect, etc. It is shown that the numerical results are in good agreement with the experimental observations in terms of time histories of impact force and displacement as well as crack distribution and propagation and that the newly developed 3D meso-mechanical model together with the previously proposed constitutive model for concrete can be used to predict the response and failure of reinforced concrete structures subjected to impact loading.

The rise of defensive engineering: how personal liability considerations impact decision-making

Based on a survey of Australian engineers (n = 275) this paper examines the impact of personal liability considerations on engineering decision-making. Almost all respondents who make high-stakes decisions saw questions of liability as having both positive (90%) and negative (87%) impacts. Our analysis shows that awareness of personal liability acts to focus the attention of many engineers on the moral dimension of their work. However, it also encourages more expensive decision-making, inhibition of innovation and professional paralysis. We argue that while personal legal liability is a legitimate way to focus engineers’ attention on the potential impact of their work, a problem arises when decision-makers are held responsible for disasters over which they had little control. The focus then shifts to ‘defensive engineering’ practices that are aimed at limiting individual liability rather than disaster prevention. Legal processes that are seen to unfairly allocate blame do not encourage practices that support future disaster prevention.

Numerical Simulation on the Yawing Performance of Grouting Steel Pipe in Exempt-incision Entrance Technology

The exempt-incision entrance technology of rock mass reinforced by grouting steel pipe is a new entrance and defense technology. By applying dynamic 3-D ANSYS/LS-DYNA10.0, this article simulated the process of GBU-28 normally penetrating into rock mass reinforced by grouting steel pipe. The analysis result proved that the grouting steel pipe contributes well to the yawing of the projectile, which can reduce the projectile’s penetration depth and obviously improve the defense performance of the tunnel entrance. This technology will be widely used in defense engineering.

Courtyard Defense Engineering of Traditional Dwellings in Henan

Defense engineering in Henan area is mainly the local fortress, but some areas have not form a fortress, but emphasize courtyard defense. This paper will analyze the composition and characteristics of courtyard defense engineering of Henan traditional dwellings through the on-the-spot investigation, hoping to show the defense engineering of Henan traditional dwellings which is different from fortress system.

A comparison of strain-rate enhancement approaches for concrete material subjected to high strain-rate

High strain-rate induced from intense dynamic loadings will cause an obvious enhancement of concrete material frequently used in civil and defense engineering, which plays an important role in correct numerical simulations of concrete members subjected to intense dynamic loadings. In this article, the existing three strain-rate enhancement approaches for concrete material are compared by three aspects, that is, flexibility of fitting data, consistency condition, and time-dependent behavior. The so-called “overstress approach” is found to be not flexible for fitting high strain-rate data and unable to well predict the strain-softening behavior but can capture the inherent viscidity of concrete material. The “consistency approach” can describe the strain-softening behavior and the inherent viscidity but may be inconvenient and time-consuming when fitting high strain-rate data. The “simplified approach” widely used in commercial concrete material models can describe the strain-softening behavior and fit high strain-rate data by a more convenient and direct way but cannot capture the inherent viscidity of concrete material. Examples of uniaxial stress including loading and unloading under constant and varying strain-rates are presented to demonstrate the above-mentioned findings, in which the updating algorithm of dynamic stress is presented in detail.

Risk-Based Software Development Practices for CREATE Multiphysics HPC Software Applications

The January/February 2016 issue of this magazine presented descriptions of the US Defense Department's Computational Research and Engineering Acquisition Tools and Environments (CREATE) program and the software engineering approach for managing its programmatic risks. This article describes the software engineering methodology deployed to manage the development risks faced by CREATE, that is, the risks arising in the product development cycle and environment. The approach here is similar to the one for the management of CREATE programmatic risks and is based on a set of shared development practices. The management of these risks is especially challenging in the environment of distributed teams developing physics-based, system-of-systems, high-performance computing software anchored in the three military departments. The CREATE experience provides a concrete example of successful implementation of best software engineering practices in a computational science and engineering milieu that has historically questioned the value of traditional software engineering wisdom and has resisted the adoption of plan-centered software engineering processes. It has allowed CREATE to adopt important software engineering practices such as use case-centered requirements management, use of pilot projects to align customer and developer expectations, continuous code integration of modular components, and scalable product support models, among others.

Safe Lithium-Ion Batteries? Predicting Performance over a Range of Operating Conditions

Electrochemical-thermal coupled modelling of lithium-ion batteries is used to simulate battery performance. Modelling can be used to investigate the effects of different materials and design parameters on battery performance and safety. Numerous models exist for lithium-ion batteries1 from microscopic through to module scale simulations. Majority of these models simulate cell performance under normal charge and discharge operation. Generally these models do not accurately predict cell behaviour outside of normal conditions, such as at high temperatures. Operating lithium-ion cells at high temperatures can lead to an internal thermal event and ultimately cell failure. A number of models have been developed to simulate cell behaviour outside normal conditions however these models do not include the performance of cells during normal operation. A model that simulates cell performance over a range of conditions is necessary to make an informed decision regarding material and design changes. This work aims to combine two existing models to create a new model for simulation of cell performance under normal and high temperature conditions. Two existing models were chosen to create the new model. The models were selected to meet the following criteria: 1) single cell model 2) stacked plate configuration 3) individual component layers modelled (no homogeneous core assumption) 4) includes temperature dependent material properties (or able to be included). The first is a 1D electrochemical-thermal reduced order model developed by Gambhire et al.2 for simulation under normal charge and discharge operation. The second is a 1D electrochemical-thermal coupled model developed by Wang et al.3 for simulating internal thermal events including decomposition reactions for each cell component. Key aspects of both models have been used to create a new model implemented in COMSOL Multiphysics®. The new model is expected to more accurately describe cell behaviour over a range of conditions. The results of this study will be presented at the conference. Acknowledgments: The authors acknowledge the funding support provided by the ARC Research Training Centre for Naval Design and Manufacturing, PMB Defence Engineering, and the CSIRO Manufacturing High Performance Metal Industries Program.

Fragmentations of Solids Under Impact Tension

Materials usually break into many pieces (fragments) under high strain-rate tension. Understanding the fragmentation properties of solids is important to the researchers in fields of physics, mechanics, aerospace and defense engineering. In this paper, we reviewed the researches on tensile fragmentation undertaken since 1940s. Recent advances in the fragmentation studies from theoretical analysis, experimental investigation, and numerical simulation are addressed. Some suggestions were provided for the future development in this field.

Guest editorial: Challenges in RF and microwave defense engineering

Guest editorial: Challenges in RF and microwave defense engineering

爆炸、冲击防护材料复合结构研究进展

本文从材料组成结构及其对性能影响的规律出发，总结了国内外大量关于抗爆炸、冲击材料复合结构的设计和研究，系统介绍了由水泥混凝土、金属、有机材料等基体材料组成的复合结构的设计方法、特点和及其防护效果，重点介绍两层材料组合结构和三层材料组合结构；期望能够为有抗爆炸、抗冲击要求的各类国防工程、人防工程，以及民用和工业建筑进行防护材料和结构的研制提供参考。 Based on material composition structure and its effects on impact performance, the literature of anti-explosion and impact composite structure design and research is summarized. The design, technical feature and efficiency of composition structure based on cement concrete, metal and organic materials respectively are summarized, especially introducing the two-layer and three-layer structures. The paper may provide a technical reference for all kinds of studies and designs about the anti-explosion and anti-impact structure of national defense engineering, civil air defense engineering, as well as civil and industrial buildings.

Basalt fiber reinforced porous aggregates-geopolymer based cellular material

Basalt fiber reinforced porous aggregates-geopolymer based cellular material (BFRPGCM) was prepared. The stress–strain curve has been worked out. The ideal energy-absorbing efficiency has been analyzed and the application prospect has been explored. The results show the following: fiber reinforced cellular material has successively sized pore structures; the stress–strain curve has two stages: elastic stage and yielding plateau stage; the greatest value of the ideal energy-absorbing efficiency of BFRPGCM is 89.11%, which suggests BFRPGCM has excellent energy-absorbing property. Thus, it can be seen that BFRPGCM is easy and simple to make, has high plasticity, low density and excellent energy-absorbing features. So, BFRPGCM is a promising energy-absorbing material used especially in civil defense engineering.

The Research of Communication System of Civil Defense Engineering Based on Siemens PPI Bus

In civil defense engineering, three anti-ventilation, air conditioning dehumidification, power supply and other electrical control equipment have long distance, distributed monitoring area and are not convenient for centralized monitoring. To improve the level of civil air defense system of automatic monitoring, enhance the system's rapid response ability, adapt to the need of modern war, this paper based on data communication problems of distributed electrical system in civil defense engineering, combined with the low communication rate and high security requirements in civil defense engineering, puts forward the communication solutions based in Siemens PPI fieldbus, configures the communications PLC which has powerful functions, compiles multipoint PPI communication program, designs remote monitoring system and gives results of test analysis when it is running. Actual operation results show that the communication system of civil defense engineering based on Siemens PPI fieldbus has fast communication speed, low error rate, strong expansibility and other advantages..

Study of Application of Thermal Infrared Camouflage Materials in the National Defense Engineering

In this paper, a series of semi-interpenetrating polymer network materials based on poly ((2-dimethylamino) ethyl methacrylate)/poly (N, N-diethylacrylamide) (PDMAEMA/PDEA) were synthesized at room temperature. The influence of this additive on the property of resulting PDEA materials was investigated and characterized. The glass transition temperature (Tg) of the semi-IPN materials was observed by Differential Scanning Calorimetry (DSC). Compared to PDEA, the semi-IPN materials exhibited excellent mutative values in response to an alternation of the temperature, and showed fast swelling and deswelling rates in response to temperature change, which suggests that these materials have potential application as thermal infrared camouflage materials.