Table of Content

28 September 2007, Volume 0 Issue 5

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BASIC STUDY

EXPERIMENTAL STUDY OF CONCRETE BEAMS STRENGTHENED WITH PRESTRESSED GLASS FIBER REINFORCED PLASTICS

Zeng, X. T., Ding, Y. H., Li, H. M.

2007, 197(5):  3-6. 

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Directing to the insufficient of concrete beams strengthened with fiber reinforced plastics,the study is focused on prestressing to glassfiber reinforced plastics and bonding prestressed GFRP on the tension surface of concrete beams to improve the load-bearing capacity of concrete beams.Considering the low shear strength capacity of GFRP,the article studies the method of prestressing to GFRP and then,9 strengthened beams with different prestress and concrete grade are done in the experiment of bending strengthening.Strengthened beams with different bonding style on the side of concrete beams with the same prestress are also made in the experiment of shear strengthening.Experiment results show that concrete beams strengthened with prestressed GFRP can enhances the cracking moment and ultimate bearing capacity and strength utilization factor of GFRP and can also lead to a much slower growth of cracks and improve resistance to deformation.

CURE KINETICS OF A TGDDM EPOXY/DDS System MODIFIED WITH POLYSULFONE NANOFIBER 

Yang, L. P., Li, P., Xue, Z. M., Li, G., Yang, X. P.

2007, 197(5):  7-10. 

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The cure kinetics and mechanisms of 4,4'-diamiodiphenyl methane(TGDDM) epoxy/4,4'-diaminodiphenyl sulfone(DDS) modified with various composition of polysulfone nanofibers are studied using differential scanning calorimetry.The results show that the autocatalytic mechanism is observed by the PSF-nanofiber-modified epoxy;the curing rate and the extend of curing of the modified system are accelerated with the addition of PSF-nanofiber.

POLYGONAL FINITE ELEMENT METHOD OF MECHANICAL PROPERTY ANALYSIS FOR HETEROGENEOUS MATERIALS

Wang, Z. Q., Li, S. P.

2007, 197(5):  11-16. 

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The popular tool to analyze mechanical properties of materials is finite element method.For particulate-reinforced composite material,the reinforced phases or inclusions are usually irregular polygons.Owing to partition dense finite elements by classically FEM to simulate heterogeneous materials,it decreases the computational efficiency.In this paper,by using polygons as computational elements and applying rational functions as trial and test functions,the polygonal finite element method for heterogeneous materials simulation is presented.The reduce formulations of Wachspress interpolation shape functions are given.Applying Wachspress interpolations as displacement functions of polygonal elements,the interelement compatibility of displacements can be automatically ensured.According to the real structure of materials,the computational grids contain some polygonal elements.Numerical examples are presented to demonstrate the performance and accuracy of the polygonal finite element method.