CRACK INITIATION POINT DETERMINATION AND DYNAMIC FRACTURE TOUGHNESS FOR CHARPY PRE-CRACKED SPECIMEN

The method to detect the crack initiation point of Charpy pre-cracked specimen under dy- namie loading was studied using strain gauge.The load-time curve and nominal strain-time curve at the crack tip for impact testing specinens may be shnultaneously measured by twin-channel oscilloscope with high speed sampling and diskette storing.Based on the dynam- ic finite element simulation of impact response of Charpy specimen,the measuring method of dynamic fracture toughness was analysed and some problems in previous dynamic fracture toughness measurement were discussed.

Modeling the blast load induced by a close-in explosion considering cylindrical charge parameters

Structural damage is significantly influenced by the various parameters of a close-in explosion.To establish a close-in blast loading model for cylindrical charges according to these parameters,a series of field experiments and a systematic numerical analysis were conducted.A high-fidelity finite element model developed using AUTODYN was first validated using blast data collected from field tests conducted in this and previous studies.A quantitative analysis was then performed to determine the influence of the charge shape,aspect ratio(length to diameter),orientation,and detonation configuration on the characteristics and distributions of the blast loading(incident peak overpressure and impulse)according to scaled distance.The results revealed that the secondary peak overpressure generated by a cylindrical charge was mainly distributed along the axial direction and was smaller than the overpressure generated by an equivalent spherical charge.The effects of charge shape on the blast loading at 45°and 67.5°in the axial plane could be neglected at scaled distances greater than 2 m/kg^(1/3);the effect of aspect ratios greater than 2 on the peak overpressure in the 90°(radial)direction could be neglected at all scaled distances;and double-end detonation increased the radial blast loading by up to 60%compared to singleend detonation.Finally,an empirical cylindrical charge blast loading model was developed considering the influences of charge aspect ratio,orientation,and detonation configuration.The results obtained in this study can serve as a reference for the design of blast tests using cylindrical charges and aid engineers in the design of blast-resistant structures.

A GENERALIZED GRADIENT PROJECTION METHOD FOR OPTIMIZATION PROBLEMS WITH EQUALITY AND INEQUALITY CONSTRAINTS ABOUT ARBITRARY INITIAL POINT

In this paper, we give a new generalized gradient projection algorithm for nonlinear optimization problems with arbitrary initial point. This new algorithm has some important advantages as follows: (1) The algorithm does not require initial feasible point; (2) It can deal with nonlinear equality and inequality constraints problems; (3) The structure of our algorithm is very simple;(4) Under some mild assumptions, it has global convergence.

Key Points of the Initial Actions for the Implementation of the Joint Statement

I. The parties held serious and productive discussions onthe actions each party will take in the initial phase for theimplementation of the Joint Statement of September 19,2005. The parties reaffirmed their common goal and will

ON THE CONVERGENCE OF KING-WERNER ITERATIONMETHOD IN BANACH SPACEON THE CONVERGENCE OF KING-WERNER ITERATIONMETHOD IN BANACH SPACE

In this paper. a Kantorovitch- Ostrowski type convergence theorem and an error estimate of using the information of higher derivatives at the center between initial points for King-Werner iteration method in Banach are established.