Advanced Materials Research Vol. 934

Abstract: To investigate the changes of corneal tissues morphological structure and biomechanical properties in different month age rabbits, the eyeballs of the 1 month, 2 month and 3 month-old-New Zealand white rabbits were obtained and getting the cornea tissues, and then measured the thickness of the cornea tissues. The first part of the corneal tissue was used to observe cornea structure with HE staining. The second part was used to observe collagen fibrils by electron microscope. The third part of the cornea tissues were cut into strips and used to test the elastic modulus of the cornea on Instron5544 tester. The thickness of the cornea was increased with month age. HE staining observation shows that the numbers of corneal fibroblasts were decreased and the fiber bundle increased with month age. Electron microscope observation shows that the diameters of collagen fibrils were increased at 2 and 3 month. Biomechanical experiment results reveal that cornea tissues elastic modulus was increased with month age. In the post-embryonic stages, the structure of cornea, the structure and number of collagen fiber, the number of corneal fibroblasts and the biomechanical properties of cornea were changed continually.

Abstract: The relative displacement between the skull and brain can be caused by road accidents and leads to permanent health issues or even death. The objective of this study is to investigate the influence of gyri and sulci on skull-brain motion with two two-dimensional finite element head models with detailed structures. The material properties were adopted from the relative literature and assigned to the different model parts. Firstly, frontal impacts were simulated by impacting the head models with the same box-shaped object respectively to enable a comparison between simulation results and experiment data. Next, the same load condition of Nahum’s experiment reported in the literature was used as input to the finite element models. The results indicate that the influence of gyri and sulci on skull-brain motion is not significant.

Abstract: A finite element model with detailed anatomical structure of human cervical spine was established in this paper based on the CT scan data of the cervical vertebrae obtained from a 50th percentile Chinese male. The model was validated by the data from the head-neck drop test conducted by Nightingale et al in 1996. In the drop test simulation, the contact force between the head and impact surface, as well as head acceleration were chosen to gauge the accuracy of the model predictions against test results. The results show that the head - neck finite element model without muscle tissue has a consistent mechanics and dynamics with the body drop test. The model can be applied to the exploration of a more detailed neck injury model with muscle tissue and can also be directly applied to the study of injury mechanism of the cervical spine in the car crash accidents.

Abstract: In this paper, a finite element model of human head was established based on CT scanning on a 40-year-old and 50 percentile Chinese male volunteer, and the model was verified with the experiment conducted by Verschueren and skull fracture was investigated during the collision. The frontal of head was impacted with different velocities during the impact tests. A break-deletion element process was represented to simulate the pathological phenomena of skull fracture.The results showed that the simulation results and experimental results were in a good consistency on both mechanics and pathology.

Abstract: Mechanical properties of the structure of human body joint always is an important research topic of biomechanics, the biomechanics of the knee joint research, this article through the establishment of a complete dynamic model of the gait cycle of human knee joint of human lower limb gait has carried on the numerical analysis, simulated by dynamic mechanical parameters of the structure of the human body joint, three-dimensional finite element model for the knee joint, through calculation and analysis to determine the rule of the inside of the knee joint dynamic stress, strain, for the study of complex shapes and complex load and complex material of human body joint provide a research idea.

Abstract: In the 19th century, Julius Wolff put forward the law of bone transformation, it has been widely known that the trabecular structure of cancellous bone depend on the mechanical characteristic of cancellous bone. At present, in the field of bone remodeling and biomechanics, FE method and computer simulation are playing important role in simulating and predicting the bone mineral density or bone structure. To establish a quantized biological model of bone growth and remodeling adaptation, which integrates animal experiments, unknown parameter inversion identification of mathematical functions and technique of computer simulation. The 80 rats were randomly divided into three groups: 15 rats were in normal control groups, 45 in experiment groups, 20 in validation and prediction groups. By designing a new animal experiment, we investigate the effects of stress environments on bone growth and remodeling of rapid growing rats. And gather the bone mineral density (BMD) of proximal femur in the same interval for the unknown parameters (B and K) inversion of bone growth. The model of bone growth and remodeling advanced in this paper can not only numerically simulate the relationship between outer stimulus and the femur BMD variation of rapid growing rats, but also predict the growth trend of rat femur under different stress environments in its whole lifecycle.In this paper, we showed that the modeling ideas and methods for human bone reconstruction tips to provide clue and reference to establishing human model of bone growth and remodeling.

Abstract: Purpose: In order to further study the physical differences between sports major and non-sport major male students, and better carry out individualized physical education. Methods: Body composition analyzer and power cycling were used to test body composition and maximal oxygen uptake for sports major and non-sport major male students. Data were analyzed by SPSS 17.0, and compared among the groups by t test. Results: The results showed that the percentage of body fat of sports majors was 10.57 ± 3.07 %, non-sport major male students’ body fat percentage was 17.66 ± 6.28 % (P<0.05), and sports majors male students’ protein content was 13.25 ± 0.64 kg, non-sport major students’ protein content was 10.98 ± 1.15 kg (P<0.05). Sports majors students’ body fluid content and maximal oxygen uptake was significantly higher than non-sport major male students (P<0.05). in addition, other indexes of body composition, sports major students were better than that of non-sport major students, but they showed no significant differences. Conclusion: This study showed that long term training engaged in sports majors students’ protein content, and body fluid content aspects were significantly higher than that of non-sport major male students and aerobic capacity was significantly better than the non-sport major students.

Abstract: In Lithuania, it has always has been an important issue to find durable and cost-effective solutions for paving low-volume roads. The conventional asphalt concrete structures were built using paving grade bitumen with the penetration of 70/100 or 100/150 over the recent 20 years. The performance of those pavements was satisfactory. As an alternative solution, the use of soft asphalt pavements was proposed. This technology is widely used in Nordic countries. But in Lithuania it has never been applied. Research on the designed soft asphalt mixtures was carried out and the trial on-site sections were constructed. The results of laboratory tests and on-site research were positive and promising. Based on that, the technology could be considered as successfully implemented and good quality was achieved.

Abstract: This work examines the processing and some mechanical properties of copper-electroplated graphite compacts. Shear and wear tests were conducted. Natural graphite (NG) flakes were compressed to make graphite compacts. No polymer binder was added in the compact. For reinforcing and preventing the NG particles from peeling off, a copper layer was electroplated on the compact. The density of green graphite compact approached a limit when the forming pressure was higher than 100 MPa. The results indicated that the shear strengths increase 150% and the wear resistance is improved more than ten times because of the copper layer. The induced damage mechanisms were examined, and the influence of the copper layer on the damage is discussed.