In this paper, someearly research on drag reduction technology is briefly reviewedand the existing representative underwater turbulence dragreduction technologies are analyzed and discussed in detail. Andthen the research actualities of riblet surface drag reductiontechnology, microbubble drag reduction technology andhydrophobic/superhydrophobic surface drag reduction technology areexpounded through experimental and theoretical researches withdrag reduction mechanisms purposively emphasized. In addition, thedrag reduction technologies by compliant coating and walloscillation are also briefly described. Finally, futuredevelopment of underwater drag reduction technology and itsapplication are prospected.

Hyper-elasticmaterials are a kind of irreplaceable macromolecule materials withunique characteristics and wide applications. Researches on theunique instability problems of hyper-elastic materials havegreatly promoted the development of finite deformation andhyper-elastic theory in the field of continuum mechanics. Variousinstability problems for hyper-elastic materials are reviewed inthis paper, such as the Rivlin cube problem, inflation ofthin-walled cylindrical tubes and thin-walled spherical shells,torsional instability of cylindrical tubes, surface instability ofcompressed or bent blocks, the formation of void and the suddengrowth and collapse of void. The characteristics and solutionmethods are then analyzed for this nonlinear problem of materialinstability, and finally, main results and future developments aregiven and discussed.

The split Hopkinsonpressure bar (SHPB) experimental technique is the most commonmethod to evaluate the dynamic mechanical properties in the rangeof strain rates from 10$^{2}$s$^{ - 1}$ to 10$^{4}$s$^{ - 1}$. Thestate-of-the-art methods in Hopkinson bar experiments aresummarized after a detailed discussion of the three classic papersby Hopkinson, Davies, and Kolsky. Advancements of the Hopkinsonbar experimental methods are discussed, including fundamentaltheories, loading techniques and improvements in measurements.Fundamentals of the Hopkinson bar experimental procedure areoutlined, including specimen design, friction effect and pulseshaping. The loading techniques consist of pulse shaping,single-pulse loading and controlled multi-pulse loading. Thequartz-crystal system, the laser system and the infrared systemrepresent recent improvements in the SHPB experimental technique.This paper provides necessary information for conducting aHopkinson bar experiment and analyzing the experimental data. Itis essential to standardize the SHPB technique and apply it toeven larger range of materials in the future.