• Journal of the Korean Society for Precision Engineering
• /
• v.24 no.11
• /
• pp.116-125
• /
• 2007

Human muscle skeletal model was developed for biomechanical study. The human model was consists with 19 bone-skeleton and 122 muscles. Muscle number of upper limb, trunk and lower limb part are 28, 60, 34 respectively. Bone was modeled with 3D beam element and muscle was modeled with spar element. For upper limb muscle modelling, rectus abdominis, trapezius, deltoideus, biceps brachii, triceps brachii muscle and other main muscles were considered. Lower limb muscle was modeled with gastrocenemius, gluteus maximus, gluteus medius and related muscles. The biomechanical stress and strain analysis of human was conducted by proposed finite element analysis model under Kumdo head hitting motion. In this study structural analysis has been performed in order to investigate the human body impact by Kumdo head hitting motion. As the results, the analytical displacement, stress and strain of human body are presented.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.3 no.6
• /
• pp.96-111
• /
• 1995

A bellows is a component installed in the automobile exhaust system to reduce the impact from an engine. It's stiffness has a great influence on the natural frequency of the system. Therefore, it must be designed to keep the specified stiffness that requires in the system. This study present the finite element analysis of U-typed bellows using a curved conical frustum element and the shape optimal design with specified stiffness. The finite element analysis is verified by comparing with the experimental results. In the shape optimal design, the weight is considered as the cost function. The specified stiffness from the system design is transformed to equality constraints. The formulation has inequality constraints imposed on the fatigue limit, the natural frequencies, the buckling load and the manufacturing conditions. A procedure for shape optimization adopts a thickness, a corrugation radius, and a length of annular plate as optimal design variables. The external loading conditions include the axial and lateral loads with a boundary condition fixed at an end of the bellows. The recursive quadratic programming algorithm is selected to solve the problem. The result are compared with the existing bellows, and the characteristics of the bellows is investigated through the optimal design process. The optimized shape of the bellows are expected to give quite a good guideline to the practical design.

• Advances in Computational Design
• /
• v.1 no.2
• /
• pp.139-154
• /
• 2016

The usage of sandwich structure is extensively increasing in lightweight protective structures due to its low density and other useful properties. Sandwich panels made of metal sheets with unfilled cellular cores are found to exhibit lower deflections by comparing to an equivalent monolithic plate of same metal and similar mass per unit density. However, the process of localized impact on solid structures involving plastic deformation, high strain rates, temperature effect, material erosion, etc. does not hold effectively as that of monolithic plate. In present work, the applications of the sandwich plate with corrugated core have been extended to develop optimized lightweight armour using foam as medium of its core by explicit finite element analysis (FEA). The mechanisms of hardened steel projectile penetration of aluminum corrugated sandwich panels filled with foams have been numerically investigated by finite element analysis (FEA). A comparative study is done for the triangular corrugated sandwich plate filled with polymeric foam and metallic foam with different densities in order to achieve the optimum penetration resistance to ballistic impact. Corrugated sandwich plates filled with metallic foams are found to be superior when compared to the polymeric one. The optimized results are then compared with that of equivalent solid and unfilled cores structure to observe the effectiveness of foam-filled corrugated sandwich plate which provides an effective resistance to ballistic response. The novel structure can be the alternative to solid aluminum plate in the applications of light weight protection system.

• Advances in Computational Design
• /
• v.1 no.1
• /
• pp.37-60
• /
• 2016

In this paper an electromechanically coupled isogeometric finite element is utilized to analyse Lamb wave excitation with piezoceramic actuators. An effective actuator design reduces the energy needed for Lamb wave excitation, which is beneficial if a structural health monitoring system should be applied for a structure. For a better understanding of the actuator behavior the piezoeceramics are studied both free and bonded at a structure. The numerical part of the analysis is performed utilizing isogeometric finite elements. To obtain the optimal performance for the numerical analysis the effect of k-refinement of the isogeometric element with respect to the convergence is studied and discussed. The optimal numerical setup with the best convergence rate is proposed and is validated with free piezoeceramic actuators. The validated model is then utilized to study the impact of actuator shape and adhesive bondline effect to the wave amplitude. The study shows that simplified analytical equations do not predict the optimal excitation frequencies for all piezoceramic designs accurately.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.17 no.2
• /
• pp.145-156
• /
• 2021

Ultrasonic Nanocrystal Surface Modification (UNSM) is a peening technology that generates elastic-plastic deformation on the material surface to which a static load of a air compressor and a dynamic load of ultrasonic vibration energy are applied by striking the material surface with a strike pin. In the UNSM-treated material, the structure of the surface layer is modified into a nano-crystal structure and compressive residual stress occurs. When UNSM is applied to welds in a reactor coolant system where PWSCC can occur, it has the effect of relieving tensile residual stress in the weld and thus suppressing crack initiation and propagation. In order to quantitatively evaluate the compressive residual stress generated by UNSM, many finite element studies have been conducted. In existing studies, single-path UNSM or UNSM in a limited area has been simulated due to excessive computing time and analysis convergence problems. However, it is difficult to accurately calculate the compressive residual stress generated by the actual UNSM under these limited conditions. Therefore, in this study, a minimum finite element peening analysis area that can reliably calculate the compressive residual stress is proposed. To confirm the validity of the proposed analysis area, the compressive residual stress obtained from the experiment are compared with finite element analysis results.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2000.04a
• /
• pp.26-30
• /
• 2000

• Structural Engineering and Mechanics
• /
• v.60 no.2
• /
• pp.225-235
• /
• 2016

Fluid impact tests on plates containing mesh reinforcement and polypropylene fibers were modeled and simulated using explicit finite element analysis software, LS-DYNA. The scabbing dimensions obtained by the experiments and the simulations were compared and crack formations were matched. The objective was to test the accuracy and fidelity of the model and to confirm that damage caused by fluid impact on the plates can be estimated with a reasonable accuracy over a wide range of impact velocity.

• Journal of the Korean Society of Safety
• /
• v.9 no.3
• /
• pp.3-12
• /
• 1994

This study employed the Eshelby's equivalent inclusion method incorporated with mean field theory to investigate the Internal stress of short fiber-reinforced metal matrix composites during static loading and the dynamic finite element analysis by using alternative unit cell model to investigate the impact behaviors during the impact loading. Using the 2124 Al-SiC system as an example, the general effects of parameters such as fiber's aspect ratio, content and modulus were examined.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.10a
• /
• pp.822-825
• /
• 1995

Linear elastic stress analysis of aluminum wheel was studied using ANSYS and Unigraphics. The load condition of wheel impact test was replaced whit static force using energy valance concept. And the results were compared with strain gaga test. The test results were good agreement with analysis results.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.20 no.5
• /
• pp.521-532
• /
• 2007

Elastic wave propagations in the semi-infinite transversely isotropic cylinder under various kinds of longitudinal impact loads are analyzed using the axisymmetric finite element method and Houbolt time-integration scheme. For which the finite element program is newly constructed and verified through the comparison of present numerical results with those by other researchers. E-type glass-epoxy composite cylinders with different fiber volume fractions are adopted and studied in detail with dynamic responses of the isotropic cylinder. Three dimensional wave motions are given in graphic form to show the realistic view of the wave propagation. Nondimensionalized dynamic characteristic variables which relate the size of finite element mesh, the time step, and the wave speed are presented for obtaining accurate and stable numerical results.