Research on Damage Law of Asterococcus muratae Kuwana

[Objective] The aim is to investigate the impact of different host plants, planting methods and directions on the damage law of Asterococcus muratae. [Method] The quantity of pests, size of female pests and quantity of ova of A. mu-ratae in Suzhou in different host plants under two planting methods and in four di-rections of a host plant were measured. [Result] A. muratae exhibits selectivity to host plants, and their quantity, female pest size and reproductive capacity are higher in Magnolia grandiflora（southern magnolia） than in other plants. The four directions of the host plant suffer to different extents, and the north part is usual y the most in-jured. Mass-planted southern magnolias are more seriously impacted than individual y-planted ones. Both size and weight of a female pest have significant linear relations with ovum quantity, and the weight of a female pest is more closely related to its ovum quantity. Based on the weight of a female pest, we can predict the exact ovum quantity according to the equation y=2E-05x＋0.003 7. [Conclusion] The research re-sults provide reference for making an effective control plan for A. muratae.

Predictive Elastoplastic Damage Constitutive Law: Establishment of Equivalence Relation between Intrinsic and Extrinsic Material Parameters

The purpose of the current work is the development and application of a new identification method of material parameters of elastoplastic damage constitutive model under large strains. A relationship relating the intrinsic and extrinsic parameters of a reference material is built and transformed in equivalence relation. Extrinsic parameters concern the shape of their experimental tensile force/elongation curve, however, intrinsic parameters deal with Swift hardening law coupled with an isotropic damage variable. The relationship is carried out from a statistical characterization of a material reference (standard-steel E24). It based on multiple linear regression of a data set obtained according to a full factor design of numerical simulations of mechanical tensile tests. All materials satisfying this equivalence relation belong to the same equivalence class. This is motivated by observing that gathered materials must behave somewhat like the reference material. The material parameters can be immediately identified by only one task by running the found relationship. The current method facilitates the identification procedure and offers a substantial savings in CPU time. However it just needs only one simulation for the identification of similar behavior instead of the few hundred required when using other methods.

Effects of Strain Rate and Fiber Content on the Dynamic Mechanical Properties of Sisal Fiber Cement-Based Composites

In this paper,a split Hopkinson pressure bar(SHPB)was used to investigate the dynamic impact mechanical behavior of sisal fiber-reinforced cement-based composites(SFRCCs),and the microscopic damage evolution of the composites was analyzed by scanning electron microscopy(SEM)and energy-dispersive X-ray spectrome-try(EDS).The results show that the addition of sisal fibers improves the impact resistance of cement-based composite materials.Compared with ordinary cement-based composites(OCCs),the SFRCCs demonstrate higher post-peak strength,ductility,and energy absorption capacity with higher fiber content.Moreover,the SFRCCs are strain rate sensitive materials,and their peak stress,ultimate strain,and energy integrals all increase with increasing strain rate.From the perspective of fracture failure characteristics,the failure of OCCs is dominated by the brittle failure of crystal cleavage.In contrast,the failure mode of the SFRCCs changes to microscale matrix cracks,multi-scale pull-out interface debonding of fibers(fine filaments and bundles),and mechanical interlock.This research provides an experimental basis for the engineering application of high-performance and green cement-based composites.

A New French Rational Design Method for Airfield Pavements

The aim of this paper is to present the results of a long-term research project consisting in the elaboration of a new rational airfield pavement design procedure applied to flexible pavements. The described methodology is based on the principles and the feedback obtained from the highway pavement design process which has been applied for more than 30 years in France as well as in many other countries. Adaptations to airfield pavements have been made, including features such as accurate traffic description, consideration of lateral wander of aircrafts for instance. The results of these developments have led to a new methodology which enables optimizing pavement designs by considering various input parameters such as the type of pavement section （runway, taxiway or apron）, the material properties and the temperature. The complete description of this method is available in the new pavement design manual and it is implemented in the dedicated software Aliz6-Airfield Pavement.