Review:Recent Progress on Poly(ether ether ketone) and Its Composites for Biomedical, Machinery, Energy and Aerospace Applications

Poly(ether ether ketone)(PEEK)has drown researchers’wide attention because of the exceptional performances such as mechanical properties,thermal stability,chemical resistance,and biocompatibility.These properties endow it with broad potential use in biomedical,engineering,and aerospace applications.In addition,multifunctional fillers have been intensively incorporated into PEEK matrix,as it is conducive to the enhanced properties,and has the desired properties in concrete applications.This review introduced the basic content and synthesis pathway of PEEKs and their composites,focusing on the various applications,including biomedical,machinery,energy storage,and aerospace applications.Considerable efforts have been devoted to explore the concrete modified method to obtain the desired performances of PEEK based materials.At the end,existing problems and development directions for the PEEK based materials were analyzed and predicted.

Research Progress and Aerospace Applications of Shape Memory Alloys

As one of the newly developing intelligent/smart materials,shape memory alloys(SMAs)have become an important material and have broad application prospects.With smart structures,the integration of SMAs as actuators and sensors in structural components,has drawn significant attention and interest in the aerospace field.In this paper,the research status of SMAs at home and abroad in recent years was reviewed,including the characteristics,classification,investigation progress and applications in the aerospace field.Finally,the development trend prospects for SMAs was also presented.

Kinetic Laws of Heating Initiated Reactions for Materials in Aerospace Applications

Cure and decomposition reaction kinetics of typical organic materials in aerospace applications are introduced.From the data of dynamic differential scanning calorimetry(DSC)experiments,and based on changes of the peak temperatures(T_(p))with different heating rates(β),a linear equation,T_(p)=T_(1)+△Tlnβ,has been obtained more reasonably.The above equation can be used to explain some laws of higher or lower of apparent activation energies(E_(a)),by which the apparent activation energy(E_(a))is nearly equal to RT^(2)_(1)/△T.A number of kinetic investigations of typical thermosetting resins and energetic materials in aerospace applications were chosen to validate the above equations.

Multi-functional SiC/Al Composites for Aerospace Applications

Multi-functional Al-matrix composites with high volume fraction （55%-57%） of SiC particles are produced with the new pressureless infiltration fabrication technology. X-ray detection and microscopic observation display the composites which are macroscopically homogeneous without porosity. The investigation further reveals that the SiC/Al composites possess low density （2.94 g/cm^3）, high elastic modulus （220 GPa）, prominent thermal management function as a result of low coefficient of thermal expansion （8 × 10^4 K^-1） and high thermal conductivity （235 W/（m.K）） as well as unique preventability of resonance vibration. By adopting a series of developed techniques, the multi-functional SiC/Al composites have managed to be made into near-net-shape parts. Many kinds of precision components of space-based optomechanical structures and airborne optoelectronic platform have been turned out. Of them, several typical products are being under test in practices.

PHM with Aerospace Applications

The application areas for prognostics and health management （PHM） methods are very broad encompassing aerospace, energy, manufacturing, defense, automotive, transportation, communication, and healthcare. PHM methodologies can provide effective means for reduction in the cost associated with the maintenance and sustainability of complex systems, equipment, and facilities through the accurate assessment of incipient damages and the reliable prediction of the remaining useful life at component and system levels, thereby enabling predictive maintenance while replacing periodic/routine maintenance scheme. Aerospace systems usually require the highest level of reliability and safety and thereby demand more advanced PHM techniques. This special column is intended to provide some sample works to showcase the latest advances and developments in PHM with aerospace applications.

Application of the titanium alloy in civil aviation

Titanium and titanium alloys have been widely used in civil aviation due to their high strength-to-weight ratio and excellent corrosion resistance. A brief history of the development of titanium for aerospace application, including application areas and reasons why aviation manufacturing uses titanium, is introduced in this study. Its future trend is analyzed and discussed as well, including information on trends of the alloy development, melting technologies, present and emerging manufacturing technologies, new alloys and some new techniques for producing low cost titanium.

A review of topology optimization for additive manufacturing:Status and challenges

Topology optimization was developed as an advanced structural design methodology to generate innovative lightweight and high-performance configurations that are difficult to obtain with conventional ideas.Additive manufacturing is an advanced manufacturing technique building asdesigned structures via layer-by-layer joining material,providing an alternative pattern for complex components.The integration of topology optimization and additive manufacturing can make the most of their advantages and potentials,and has wide application prospects in modern manufacturing.This article reviews the main content and applications of the research on the integration of topology optimization and additive manufacturing in recent years,including multi-scale or hierarchical structural optimization design and topology optimization considering additive manufacturing constraints.Meanwhile,some challenges of structural design approaches for additive manufacturing are discussed,such as the performance characterization and scale effects of additively manufactured lattice structures,the anisotropy and fatigue performance of additively manufactured material,and additively manufactured functionally graded material issues,etc.It is shown that in the research of topology optimization for additive manufacturing,the integration of material,structure,process and performance is important to pursue high-performance,multi-functional and lightweight production.This article provides a reference for further related research and aerospace applications.

A new approach to time domain analysis of perturbed PWM push-pull DC-DC converter

In this paper, an analytical technique is presented for time domain analysis （transient and steady-state response） of perturbed PWM push-pull DC-DC converter using interesting corollary on Kharitonov＇s theorem. The main advantage of the proposed analysis is that even though the transfer function model of a PWM push-pull DC-DC converter is perturbed, the complete analysis has been done on a linear transfer function model of a PWM push-pull DC-DC converter. The proposed analysis is verified using MATLAB simulation. This analysis will be very much useful to power electronics engineers, since the technique is very simple and computationally efficient and easily applicable in precise applications such as aerospace applications.