Light-weight metal or alloy was widespread in aerospace and aeronautical engineering. Alloy Li-Mg was the lightest
metal structural materials. Focus was recently on this alloy. Static mechanical properties were important for materials
before they were applied into practical use. Static Testing of a new alloy Li-Mg was accomplished in this paper by
universal materials testing system Model INSTRON 5500R. Stress-strain curve was acquired. And ultimate stress, yield
stress, elongation in percentage and reduce of area in percentage were measured in detail. The result showed that alloy
had higher strength to 250MPa in tension. But the deformation was hardly changed in length or section before it cracked.
All the experimental result proved that this material was typical brittle materials. Fractography had been observed by
scanning electron microscope (SEM). SEM Photos were also verified alloy Li-Mg was ductile material.
The interest for continuous basalt fibers and reinforced polymers has recently grown because of its low price and rich
natural resource. Basalt fiber was one type of high performance inorganic fibers which were made from natural basalt by
the method of melt extraction. This paper discusses basic mechanical properties of basalt fiber. The other work in this
paper was to conduct tensile testing of continuous basalt fiber-reinforced polymer rod. Tensile strength and stress-strain
curve were obtained in this testing. The strength of rod was fairly equal to rod of E-glass fibers and weaker than rod of
carbon fibers. Surface of crack of rod was studied. An investigation of fracture mechanism between matrix and fiber was
analyzed by SEM (Scanning electron microscopy) method. A poor adhesion between the matrix and fibers was also
shown for composites analyzing SEM photos. The promising tensile properties of the presented basalt fibers composites
have shown their great potential as alternative classical composites.
Long span beams with wide-flange in w shapes section commonly appeared to support deck in various ships. Many holes
in web of the beam were punched into a few shapes because it was necessary for wires through them in the process of
building of ship. Basically, shapes of holes were circular and elliptic and positions were in mid-span or near to two ends.
Stress concentration of holes had to take into account in the design and reasonable measurements enhanced strength
around the holes had to be properly applied. A new mixed geometric similarity theory was applied to produce many
types of models of long-span beam with holes in web, in which dimension ratio varied with different parts of beam in
order to avoid a part of model beam was too thin. Many models of beam were made from a new photoelastic materials
with low freezing temperature (50°C~70°C). Different types of Loading and constraints were simulated. Thus,
isochromatic fringe patterns were obtained in circularly polarized light field. Factor of stress concentration were
calculated and conclusion were drawn through fringe patterns. Methods were acquired to enhance strength of beam and
reduce stress concentration.
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