A strut tower brace is one of the components that can improve the driving stability of a vehicle. This component has received steady attention for a long time due to its affordable price and easy installation. However, strut tower braces sold in the market have different structures. Moreover, most of them do not contain sufficient information related to safety or stability. Thus, this study aimed to analyze and compare structural behaviors of strut tower braces having various body shapes under bending and compressive scenarios. For this purpose, this study selected six representative models in the market and calculated structural behaviors (stress and deformation) using finite element analysis. Results revealed the body shape had a decisive effect not only on the durability of the strut tower brace, but also on the safety and stability of the vehicle. Among the six models tested, the model having a body shape with a single-axis form utilizing a wide rectangular cross-sectional showed the best bending and compressive performances. This study also confirmed that bending and compressive performances could be simultaneously improved depending on body shape.

In this study, based on directed energy deposition (DED) technology, one of the additive manufacturing technologies, a porous material fabricated by mixing various aluminum alloys and foaming agent was manufactured. First, the foaming agent formed pores inside the deposited materials and differences in foaming characteristics were observed depending on the type of aluminum. Also, the foaming characteristics according to the laser power, which is a representative process variable, were analyzed. As a result, a closed-cell porous material with a maximum porosity at a laser power of 1,100 W was manufactured. Results of the compression test showed that the porous material made by the pores generated therein collapses to absorb energy, and the internal pores disappear to become high density. Therefore, Young’s modulus and yield stress were reduced by the pores inside the sample of pure aluminum and Al6063. However, it was found that the specific energy absorption, which is an advantage of the foamed materials, increased compared to non-porous materials. The findings of this study confirmed that it was possible to manufacture DED-applied foam materials using aluminum powder and a foaming agent.

The literature states that the existing guidelines mainly focus on the ultimate strength of uniform corroded joints in the Jacket-type re-assessment. However, joints are non-uniformly corroded in different shapes in reality. Results derived from theoretical equations in these scenarios are significantly different from the actual capacity of the frame joints. This paper studies the influences of thickness and corroded area on the T- joint’s ultimate strength for a chord based on the numerical model ABAQUS. Numerical results show the effects of location and dimension at corroded areas on the tubular joint ultimate strength. Moreover, this research proposes a new formula based on API to estimate the strength of T-joints connected with non-uniform corroded compressive braces in certain conditions. This equation is validated by comparison of the numerical simulation in independent cases.

Carrying heavy objects in agricultural and industrial sites is the most basic labor, which requires a lot of energy. Many equipment such as crane, chain block, elevator, and forklift truck has been developed to reduce human power. Nevertheless, many tasks require human labor. In addition, rapid aging is increasing musculoskeletal diseases in industrial workers. Consequently, various muscle auxiliary wear robots and devices are being developed. In this study; a passive upper limbs exoskeleton (H-Frame) was developed to help carry over 20 kg of weight in industrial and agricultural sites. For the functional test of the developed H-Frame, tests were carried out for 20, 30, and 40 kg of each box. To measure the objective and numerical data of the H-Frame, various sensor values such as EMG (Electromyography), harness compression force sensor, and load cell value of side support and rope were measured. EMG and metabolic experiments were also performed on 8 subjects before and after wearing the device. The average value of the upper extremity muscle showed a 44% reduction effect after wearing. The device helped the wearer when carrying heavy objects. It could help prevent musculoskeletal diseases in industrial and agricultural fields.

The bone compression and the inertia from cochlear fluid or middle ear (ME) ossicles, are generally considered to be important components inducing bone-conducted (BC) hearing. To clarify the bone compression effect on the BC hearing caused by variation of Young’s modulus of skull, two different types of three-dimensional finite-element models were used in this study. The FE models were (1) Isolated cochlea model comprising ME and cochlea containing basilar membrane (BM) and (2) Head model comprising the isolated cochlea structure. The model was validated by comparison of cochlear responses such as BM velocities with those of otosclerosis patients’ clinical data. Additionally, results showed that the bone compression effects on a BC hearing is highly depended on the Young’s modulus of a skull. Also, the bone compression effects could be underestimated at low frequencies in temporal bone experiments, whereas the effects could be overestimated at high frequencies in cadaver experiments.

Rubber is positioned as an important material and essential tool and means for mass production of products in all industries due to its unique properties such as sealing, elasticity and shock absorption. However, in the case of conventional press rubber molding, its energy efficiency is low due to considerable heat loss, and the deviation of the temperature distribution of the molding mold is high due to the indirect heating method in which heat is transferred to the upper and lower molds installed on hot plates. The upper and lower heating plates were heated by several heaters installed on the hot plates. The high deviation of the temperature distribution causes unformed defects. Among the rubber mold working methods that consume considerable energy, this study attempted to reduce energy consumption by directly heating the mold via installing a heater inside the upper and lower molds in a compression mold with large energy loss. As a result, compared to the conventional method of transferring heat to the mold by heating the hot plate of the press, energy was saved by 30%, the initial mold heating time was shortened by 20 minutes, and the product defect was reduced with a rate of 25%.

Microlattice is well known as an efficient structure having a low density which maintains mechanical properties, so microlattice is being applied to the structural design of lightweight material in many industrial fields. In this study, we proposed a core-shell microlattice structure by the conformal coating of a metal nanoparticle-polymer composite in order to enhance the mechanical properties of polymeric microlattice printed by light-based 3D printing method. Polymeric architected microlattice was fabricated using digital light printing, which enabled the printing of complex structures with good surface smoothness. Then, the polymeric microlattice was conformally coated with aluminum nanoparticle-polymer composites. To investigate the effect of the metal nanoparticle-polymer composite coating on the mechanical properties of the microlattice, we studied the compressive behavior of cubic and octet-truss microlattices. As a result, we confirmed that both compressive strength and toughness of the two types of microlattices were effectively increased by coating with aluminum nanoparticle-polymer composites.

The present investigation studies the effects of heat treatment temperature on the corrosion behavior of cold worked 6111 aluminum alloy. The specimens were cold worked at different cold working ratios, namely, 10, 20, and 40%. They were then heat treated at 100, 200, and 400°C. Corrosion tests were performed using tap water with 0.01 M sodium hydroxide, as a corrosive medium, and the weight loss of the corroded specimens plus the corrosion rates were then calculated. Experimental results showed that corrosion rates depended on the amount of cold working percentage and the heat treatment temperature. Corroded surfaces were also photographed and analyzed. The graphs revealed large numbers of corrosion pits, in addition to crevice corrosion and fine grains of rust, and these rusts were cultivated to scales that were detached from the surfaces and were subjected to corrosive medium.

In this work, the degradation progression of a polyurethane (PU) hydraulic reciprocating seal with respect to the sliding distance were investigated using a pin-on-reciprocating tribo-tester. Also, the acceleration effect of alumina particles added in lubricant on degradation of PU seal were assessed, with an aim to contribute to the development of accelerated wear testing methods. As a result, It was shown that the height of PU specimens decreased drastically at the initial stage of sliding. Then, the height decrease was found to become gradual as sliding distance further increased. The result also shows that the height decrease of the PU specimen was mainly due to the effect of the compression set and wear. In addition, the noted abrasive wear of the PU specimens was found to be significantly accelerated due to the alumina particles in lubricant, which determined a further result in 50 % faster height decrease with increasing sliding distance, as compared to the normal lubricant. The outcome of this work may provide significant and useful information for the prediction of the lifetime of a hydraulic reciprocating seal, and for the continued development of accelerated wear testing of the hydraulic reciprocating seal.