In the manufacturing of bulk graphite, pores produced by vaporization and discharge of volatile materials in binders during carbonization reduce the density of bulk graphite, which adversely affects the electrical conductivity, strength and mechanical properties. Therefore, an impregnation process is introduced to fill the pores and increase the density of bulk graphite. In this study, bulk graphite is prepared by varying the viscosity of the impregnant. The microstructure of bulk graphite is observed. The flexural strength and electrical resistivity are measured. As the viscosity of the impregnants decreases and the number of impregnations increases, it is shown that the number of pores decreases. The density before impregnation is 1.62 g/cm3. The density increases to 1.67 g/cm3 and porosity decreases by 18.6 % after three impregnations using 5.1 cP impregnant, resulting in the best pore-filling effect. After three times of impregnation with a viscosity of 5.1 cP, the flexural strength increases by 55.2 % and the electrical resistivity decreases by 86.76 %. This shows that a slight increase in density due to the pore-filling effect improves the properties of bulk graphite.

Recycling is required for all disused vehicle since 2015. The resource recycling act also recommends that most disused vehicle parts have to be reused except for steering and brake parts. Since vehicle windshields should provide protection for drivers and passengers, they need high structural strength and reliability. However, the vehicle windshields themselves contain many defects arising from glass production process. Because the vehicle windshields are exposed to harsh road conditions, they are expected to experience the formation and growth of surface cracks, which can result in sudden failure. In this study, equibiaxial flexural strength tests are performed on used vehicle windshields to examine whether or not the parts can endure high impact stress due to foreign flying objects. The following conclusions can be drawn: (1) The equibiaxial flexural strength of used vehicle windshields fits the two-parameter Weibull distribution. The equibiaxial flexural strength with a 99.9% failure probability is 69MPa for used vehicle windshields. (2) The equibiaxial flexural strength with six sigma quality level and maximum principal stress at vehicle windshield under high impact load are 8.05MPa and 23MPa respectively. Therefore, Structural safety factor of used vehicle windshields is 0.35 and so we should prohibit used vehicle windshields from keeping in reuse.

Complete closed-type carbon fiber reinforced polymer stirrups with a rectangular section (CFRPRS) were developed and tested in this research. The CFRPRS was intended to relieve stress concentration and to reduce the number of kinked fibers at the bent portion. A total of 16 B.5 specimens were tested regarding the bend strength of the CFRPRS and CFRP stirrups with circular section. Test results showed that CFRPRS improved the bend strength compared to its counterpart of conventional CFRP stirrups having a circular section, with the larger ratio of width to thickness being more effective for the same sectional area. The best correlation between the test results and predictions on CFRPRS bend strength was observed when the section of CFRPRS was modeled as a collection of transformed individual circular sections.