On the effect of pitch and yaw angles in oblique impacts of smallcaliber projectiles

A terminal ballistic analysis of the effects of 7.62 mm × 51 AP P80 rounds on inclined high-strength armor steel plates is the focus of the presented study.The findings of an instrumented ballistic testing combined with 3D advanced numerical simulations performed using the IMPETUS Afea? software yielded the conclusions.The experimental verification proved that slight differences in the pitch-andyaw angles of a projectile upon an impact caused different damage types to the projectile’s core.The residual velocities predicted numerically were close to the experimental values and the calculated core deviations were in satisfactory agreement with the experimental results.An extended matrix of the core deviation angles with combinations of pitch-and-yaw upon impact angles was subsequently built on the basis of the numerical study.The presented experimental and numerical investigation examined thoroughly the influence of the initial pitch and yaw angles on the after-perforation projectile’s performance.

On the Definition of Propellant Force

Comments are given on the various physical definitions of the force constant of propellant. As there are more or less defects in these definitions, two new definitions are presented to reflect the physical essence of propellant force more perfectly and could well compatible with the mathematical expression.

Deformation,fragmentation and acceleration of a controlled fragmentation charge casing

Two different finite element software,LS-DYNA and Impetus,have been evaluated to test their ability to predict the deformation,fragmentation and acceleration of a controlled fragmentation charge casing.The general-purpose program LS-DYNA was used with a multi-material ALE formulation and a masspreserving erosion criterion coupled to a Johnson-Cook fracture criterion.In the Impetus simulations,a third order Lagrangian element formulation was used for the casing and a node-splitting element erosion treatment coupled to a Cockcroft-Latham failure criterion was used to describe casing fracture.The high-explosive gases were described by a discrete particle formalism.In order to acquire data to validate our computational tools and constitutive models,a series of experiments have been performed using a laboratory charge with an internal grooved casing.In the test series,the charge geometry was fixed except that the groove depth were varied from very shallow to very deep resulting in different deformation patterns,fracture modes and terminal velocities.Various diagnostic tools captured the different stages of the expansion and fragmentation of the casing.A high-speed framing camera depicted the deformation pattern before fragmentation and was used to determine the moment when the casing failed.Three different complementary techniques were used to follow the acceleration of the fragments;a Photon Doppler velocimetry to determine the initial acceleration of the casing,double exposed radiographs to estimate the fragment velocity after break-up and a high-speed video to determine the terminal velocity of the fragment after leaving the fireball.In addition,the fragments were soft recovered in a set of sawdust pit tests and their final shape and weight were measured.A SEM was used to characterise the fracture surfaces and to determine the modus of fracture(tensile or shear failure).Comparisons to experiments show that both software can predict the change in deformation behaviour when the groove depth increases,from tangential necking for shallow grooves to radial punching for deep groves.Both software could also reasonable well predict the acceleration of the fragments,though both overestimates the terminal velocity for the charge with the deepest grooves.

THE SLIDING SURFACE ALGORITHMSINTHREE－DIMENSIONAL DYNAMIC FINITE ELEMENT CODE

In this paper, the sliding surface algorithms in dynamic finite element analysis ofhigh velocity impact are presented. With these algorithms, the momentum and theangular momentum of the element can be conserved. The calculated examples showthat the calculation using these algorithms in dynamic finite element analysis of highvelocity is valid and stable.

Global Celebration of Chinese New Year with the Highlight of Combining Cultural and lourism Resources

More than 1,500 cultural programs will take place in 396 cities in 133 countries and regions during the Happy Chinese New Year 2019 under the cooperation with nearly 1,000 partners around the world. One of the highlights is an excellent combination of Chinese cultural and tourism resources. Various cultural experience and tourism promotion activities complement each other, injecting new impetus into the promotion of Chinese New Year as an international festival shared by the world.

Impetus for Export-Oriented Economy——Review of foreign capital utilization in Hunan during the Eighth Five-Year Plan period

Since its implementation of the openingpolicy,China has witnessed greatsuccess in foreign fund utilization.Hunan,situated in the hinterland,beganto introduce foreign capital a little later thanthe coastal areas.In 1979,Hunan began toconduct processing and assembling businessand compensation trade,but gained only afew million US dollars.A vast change wastook place in the Eighth Five-Year Planperiod,achieving a great quantitative andqualitative rise in foreign capital utilizationas compared with the sixth and seventh Five-Year Plan periods.In the past five years,Hunan has approved 4,001 foreign-fundedprojects,a 5,5-fold increase over the total forthe previous 12 years(1979-1990),including3,584 projects directly financed by

The Logic of Practice and Development Opportunities of Digital Transformation of Education

“Digital transformation of education”is a hot topic of present educational reform and the development tendency of future educational innovation.Digital transformation of education,as a process stressing technology-driven educational innovation and reform,boasts the importance of development in its birth and practice.It is driven jointly by social and cultural transitions,the impetus of technical innovation,the guidance of national policies,and the endogenous development of the education system.The logic of practice of the transformation can be regarded as the behavior choice dominated by value and intentions,and the underlying generation principles in practice comprise the“problem-driven+concept-led”principle,the“system evolution+innovative breakthrough”principle,and the“value assessment+iterative optimization”principle.At present,under the background of constructing the new ecology of a smart society and a high-quality education system,and under the pressure of COVID-19 pandemic,the transformation faces golden development opportunities.Nonetheless,the present transformation practice still has some differences from the expected value orientation.Therefore,it is required to research and develop a mature digital education model or framework,carry out a national digital education preparation campaign,work for pilot schemes for the transformation at all levels and of all kinds,attach importance to theoretical research on education relating to the digital transformation of education,and more actively embrace the new wave of educational reform worldwide.

INJECTING IMPETUS

China continues to drive up consumption to boost the economy As China steps into the Year of the Pig,which symbolizes good fortune,it is also striving to achieve prosperity commensurate with its implications.Before the Lunar New Year on February 5.

Tourism Becomes Shanghai’s New Impetus

Shanghai, dubbed "China’s Pearl of the Orient," is particularly beautiful in autumn. Tourists could smell the fragrance of sweet osmanthus and also feel a joyful atmosphere everywhere in Shanghai due to Shanghai Tourism Festival 2011,

New Impetus

Chinese and North Korean leaders reaffirm their commitment to stronger