• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.06a
• /
• pp.1222-1227
• /
• 2000

The optimization study are carried out for helicopter rotor blades with composite box-beam spar. The objective function is to minimize the weight of rotor blades subject to frequency, aeroelastic stability and failure constraints. Design variables include the number of ply and ply angles of the laminated walls. The beam model of a hinge less rotor blade is based on a large deflection beam theory to describe the arbitrary large deflections and rotations. The p-k method and unsteady two dimensional strip theory are used to calculate aeroelastic stability boundary.

• Journal of the Korean Society for Precision Engineering
• /
• v.12 no.12
• /
• pp.165-172
• /
• 1995

Many algorithms to enhance a speed performance of a robot have been studied, but it's rare to consider disign aspect of a robot arm for time optimal problem. In this paper, section demensions of a robot arm and a velocity profile of an end-effector were optimally designed to minimize the cycle time. Capacity of actuators, deflections of end-effector, and a fundamental natural frequency of the robot arm were constrained in optimal design. For a given path with a trapezoidal velocity profile, torques of each joint were calculated using the inverse kinematics and dynamics. For the SCARA type robot which is mainly used for assembly tasks, the time optimal design of each robot arm id presented with the above constraints.

• Transactions of Materials Processing
• /
• v.16 no.1 s.91
• /
• pp.15-19
• /
• 2007

This paper presents an integrated machining error compensation method based on captured images of tool deflection shapes in flat end-milling processes. This approach allows us to avoid modeling machining characteristics (cutting forces, tool deflections and machining errors etc.) and accumulating calculation errors induced by several simulations. For this, a high-speed camera captured images of real deformed tool shapes which were cutting under given machining conditions. Using image processes and a machining error model, it is possible to estimate tool deflection in cutting conditions modeled and to compensate for machining errors using an iterative algorithm correcting tool paths. This corrected tool path can effectively reduce machining errors in the flat end-milling process. Experiments are carried out to validate the approaches proposed in this paper. The proposed error compensation method can be effectively implemented in a real machining situation, producing much smaller errors.

• Transactions of Materials Processing
• /
• v.23 no.4
• /
• pp.206-210
• /
• 2014

The metal lead frame, a semiconductor component, has product tolerances in micro units as compared to products made with a larger size mold. Therefore, small deflections of the mold and of the press as well as the press molding process itself have a strong influence on accuracy of the product. Hence, it is necessary for the process design to consider the structural response of the mold and the press during deformation. In the current study, the mold deflection and pressure on the punch is examined using the finite element modeling (FEM) program ABAQUS. The results from the simulation were verified with the dynamic deformation measurement equipment using digital image correlation (DIC).

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.04a
• /
• pp.470-475
• /
• 2000

This research covers the resting of precast/prestressed concrete I-Girder bridge. The research was designed to examine processes for improving the condition evaluation and rating of prestressed concrete bridge. To establish procedures that allow for the full utilization of prestressed concrete bridge capacity, a 28-year old sample was loaded to failure in site. The bridge was constructed with 12 spans, and girders of each span were simply supported. At each loading stage, the deflections, reinforcement strains, prestressing wire strains and concrete strains were examined. Failure behavior was analyzed, and failure load was also evaluated. The test results wee compared to the analytical results from the non-linear finite element analysis.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.04a
• /
• pp.433-439
• /
• 2000

Reinforced concrete beams show increased ductile behavior when the compressive concrete is confined with transverse steel. In the inelastic range, the most variations of ductile behaviour are defined the equivalent length of the plastic hinge and the plastic hinge rotation. In an investigation to study the influence of such confinement, sixteen reinforced concrete beams were tested in flexure and the deflections noted at all stages of loading. For all the beams tested, the plastic hinge rotation have been computed and the effect of confinement on the same examined. The conclusions are summarized as follows: The equivalent lengths of the plastic hinge are ranged within the effective depth comparatively. The ability of the plastic hinge rotation of the reinforced concrete beams confined with transverse steel are enlarged when transverse reinforcement content are increased, but the spaces are more important as the shear force are largely increased.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1997.10a
• /
• pp.633-638
• /
• 1997

This study was performed to investigate the fatigue behaviour and fatigue damage process of RC structures under repeated load. Especially, the behavior of RC beams subjected to flexure-shear force has been focused. The test results show that the deflections of beam and the strains of longitudinal steels and stirrups under cyclic loads increase with constant rate, and these increases depend on diagonal crack openings and strain increases. The present study provides useful data for the analysis of damage accumulation of reinforced concrete beams under repeated loadings.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1997.10a
• /
• pp.450-455
• /
• 1997

In recent years the research and development about the new material proceeds rapidly and actively in building industry. We are concerned with high-strength concrete as a new material. As the building structure becomes bigger, higher and more specialized, so does the demand of material and member with high strength for building expands greatly. In the future, we will quite need to research repair and rehabilitation to make high strength concrete structural building for our safe. So, I did an study on carbon fiber sheet rehabilitation(CFSR) of reinforced high strength concrete beams. The carbon fiber reinforced plastic(CFRP) bonding method is widely used for reinforcing the existing concrete structure among the various methods. The test results indicate that CFS is very effective for strengthening the damaged beams and controlling deflections of the repaired beams. When carbon fiber sheet rehabilitation of reinforced high strength concrete beams happened diagonal crack, the increase in the number of CFS layer didn't effect the increase in strength of beams. Also, by changing the CFS stick position gave diversified ultimate load in CFSR beams.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.05a
• /
• pp.591-596
• /
• 2003

Many studies have dealt with strengthening by epoxy-bonded CFRP(Carbon Fiber Reinforced Polymer) composites. However, the effects of various influencing factors have not been clarified on the behavior of strengthened RC beams. This study was performed to verify the effects of strengthening due to various bond details of externally attached CFRP Composites. In this study, major test parameters include the bond type and the anchor type. The deflections, failure load, strain of reinforcing bar, concrete and CFRP are measured at each loading step. The failure mode and debonding loads(ultimate loads) are analysed from these measured data. According to the test results, all specimens are failed by intermediate flexural crack induced interfacial debonding.

• Advances in Computational Design
• /
• v.5 no.2
• /
• pp.177-193
• /
• 2020

In the present research, dynamic analysis of functionally graded (FG) graphene-reinforced beams under thermal loading has been carried out based on finite element approach. The presented formulation is based on a higher order refined beam element accounting for shear deformations. The graphene-reinforced beam is exposed to transverse periodic mechanical loading. Graphene platelets have three types of dispersion within the structure including uniform-type, linear-type and nonlinear-type. Convergences and validation studies of derived results from finite element approach are also presented. This research shows that the resonance behavior of a nanocomposite beam can be controlled by the GPL content and dispersions. Therefore, it is showed that the dynamical deflections are notably influenced by GPL weight fractions, types of GPL distributions, temperature changes, elastic foundation and harmonic load excitation frequency.