This paper describes some locomotion modes of small aquatic and beach creatures. Some locomotion mechanisms of small living things which live in underwater and the seashore were analyzed by a digital high-speed video camera system. Test living things in this paper were zooplanktons, opossum shrimps, cirolanid isopods, and amphipods. Free swimming and tethered swimming of small aquatic creatures were analyzed from the viewpoint of hydrodynamics. Walking and jump behavior of small beach creatures were analyzed from the viewpoint of kinetics. A swimming mechanism propelled by the magnetic torque was manufactured in order to investigate the swimming characteristics of aquatic creatures. Frequency characteristics of artificial mechanism were also examined experimentally. The diversity of locomotion characteristics of small aquatic and beach creatures was clarified from the viewpoint of dynamics.

View full abstract

    The foot joint has the great mechanisms. One of them is its arch structure. This makes bipedal locomotion possible. However, the mechanism is not elucidated, so engineering research is required. Experimental analysis by a photoelasticity method was done in this research. It targeted the normal foot and the flatfoot. The change in the height of an arch was investigated. All loads were static loading. The experiment model was a frame model without the tendons of a muscle. A pilot experiment of a 2-dimensional model was done. The cross-section of the inner side arch and the outside arch was made. It was divided into four by the bone positions. The simple stress distribution map of a foot arch was obtained. The 3-dimensional experiment was done with the result of two dimensions as reference. The 3-dimensional stress freezing method was used. All the bones of the foot joint were made separately. The stress distribution map showed some things. In a normal foot, the stress of a Calcaneus ground plane decreases outside. A flatfoot has much more stress concentration. Change in an arch influences the load distribution.

View full abstract

    Loss of fixation at interfaces among stem/bone cement/cortical bone can contribute to clinical loosening of cemented total hip arthroplasty (THA), though PMMA cements are widely used to fix the prosthesis into the cortical bones for joint arthroplasty. It has been frequently reported that micromotion at the interfaces among the stem/bone cement/cortical bone is one of leading causes of the loosening. Therefore, it is really important to measure the deformation behavior of these interfaces. However, few studies have been conducted from the view point of experimental mechanics, which enables to obtain displacement and strain distributions, because the experimental approach is difficult and complicated. Then, the distribution has not been fully verified yet. In this study, microscopic deformation at these interfaces was measured by using a digital image correlation method. Specimen was composed of a tapered Ti-prosthesis, PMMA bone cement, and bovine femur. Compressive load was applied to the specimens. The results show that the micromotion at these interfaces was directly observed in this experiment, and the micromotion was larger at the interface between stem/bone cement compared to the interface between bone cement/cortical bone. Strains severely concentrated in the bone cement near the interface between bone cement/cortical bone. Shear strain concentration was particularly prominent in the bone cement. The normal strain distributions were strongly dependent on the intraspinal configuration of the cortical bone.

View full abstract

 The modern and widely known artificial hip joint developed by John Charnley in the 1970s consisted of three parts, 1. a metallic femoral stem, 2. a UHMWPE acetabular liner, 3. a metallic acetabular socket or bone cement. Acetabular liner has a bearing surface of UHMWPE which has a low coefficient of friction and low wear rate. In the long term, wear particulate dose accumulate and lead to a condition known as osteolysis, which leads to bone loss, joint loosening, discomfort, and ultimately limits the lifespan of the artificial joint. Therefore, the evaluation of the wear on acetabular bearings, which depends directly on contact pressure, is essential to analyze the failure of the acetabular implant, as well as for a better design of artificial joint. The objective of the present study was to develop a method of applying discrete element analysis (DEA) based on rigid-body-spring-model (RBSM) to artificial hip joint, using patient-specific 3D bone model and motion capture data, and to analyze the stress distribution on bearing surface during gait motion. The two peaks in peak stress were observed with a maximum value of 12.3 MPa and the corresponding contact area was 21.8% of total bearing area, and small contact area less than 25% at the edge of the superior bearing surface was observed during gait motion.

View full abstract

  In order to improve the education for space recognition of design engineers, the solving process of MCT (Mental Cutting Test) problems are analyzed and new teaching problems are developed. The developed problems were applied to the freshmen of Osaka Electro-Communication University. The new developed problems were evaluated through the MCT results which were obtained before and after solving the developed problems. The new problems were proven to be effective to space grasp abilities.

View full abstract

    The questionnaire was carried out in order to examine the relationship between design experience and job ability of the engineer which belongs to occupational cohort. The data were statistically analyzed by using the multivariate analysis software (JUSE Stat Works ver4.0). Job ability of the mechanical design engineer is classified into six clusters. The cluster in which the job ability is maintained high level with no relation on the design experience is considered the field which the university education should shoulder.

View full abstract

   The experimental results for a photoelastic model fabricated by stereolithography are presented. The stereolithograhy is possible to automate production of the photoelastic model. It is desirable to use stereolithograhy for the automation of the photoelasticity. The fabricated models have many concavities on their surfaces. The influence of surface, residual stresses in the model and applied stresses were quantitatively examined by experiments by a conventional method and an immersion method. Stress analysis is possible in the conventional experiment, despite the intensity varying irregularly in the measured images. In the immersion experiment, the intensity in the measured images is uniform so that the images of the analysis results are clearer than those obtained in the conventional experiment. This demonstrates that models fabricated by stereolithography are useful for photoelastic models.

View full abstract