• Structural Engineering and Mechanics
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• 제88권6호
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• pp.609-623
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• 2023

The objective of this study is to investigate the distribution of von Mises stress, peeling stress, and shear stress in the adhesive layer used to bond two composite panels, considering various parameters using a three-dimensional finite element method. The stiffness of the materials and the effect of the stacking order on the amount of load transferred to the adhesive layer were examined to determine which type of laminate generates less stress at the bond line. The study analyzed six different stacking sequences, all with a common first layer in contact with the adhesive and a 0° orientation. Additionally, the impact of using hybrid composites on reducing bond line stress was investigated.

• Tribology and Lubricants
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• 제39권5호
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• pp.190-196
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• 2023

Anti-adhesion coatings are very important in the processing of adhesive materials such as optical clear adhesive (OCA) films. Choosing the appropriate release coating material for dies and tools can be quite challenging. Hydrophobic surface treatment is usually performed, and its performance is often estimated by the static water contact angle (CA). However, the relationship between the release performance and the CA is not well understood. In this study, the water CAs of surfaces coated with anti-adhesion materials and the peel strengths of the acrylic-based adhesive films are evaluated. STC5 and SUS304 are selected as the base materials. Base materials with different surface roughnesses are produced by hairline finishing, mirror-polishing, and end milling. Four fluoropolymer compounds, including a self-assembled monolayer, are selected to make the base surface hydrophobic. Static, advancing, and receding CAs are mostly increased due to the coating, but the CA hysteresis is found to increase or decrease depending on the coating material. The peel strengths all decreased after coating and are largely dependent on the coating material, with significantly lower values observed for fluorosilane and perfluoropolyether silane coatings. The peel strength is observed to correlate better with the static CA and advancing CA than with the receding CA or hysteresis. However, it is not possible to accurately predict the anti-adhesion performance based on water CA alone, as the peel strengths are not fully proportional to the CAs.

• 접착 및 계면
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• 제23권4호
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• pp.108-115
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• 2022

본 연구에서는 표면처리된 Cu 리드프레임과 에폭시 컴포지트의 접착강도를 향상시키기 위하여 신규 고분자 접착증진제인 poly(itaconic acid-co-acrylamide) (IAcAAM)를 합성하였다. 이타콘산과 아크릴아마이드를 포함하는 IAcAAM은 라디칼 수성 중합을 통해 제조되었다. IAcAAM의 구조 및 물성은 FT-IR, ¹H-NMR, GPC 및 DSC로 분석하였다. Cu 리드프레임의 표면은 고온, 알칼리, UV 오존으로 처리하였다. 표면처리 후 Cu 리드프레임의 접촉각이 감소함에 따라 Cu 리드프레임/에폭시 컴포지트의 접착강도는 증가하였다. 에폭시 혼합물에 IAcAAM을 첨가함에 따라 Cu 리드프레임/에폭시 컴포지트의 접착강도가 증가하였다. 또한, 에폭시 혼합물에 실리카 함량이 증가할수록 Cu 리드 프레임과 에폭시 컴포지트의 접착강도는 약간 감소하는 경향을 나타내었다.

• 대한치과기공학회지
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• 제37권1호
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• pp.17-21
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• 2015

Purpose: In this study, Spreadability of denture adhesive in accordance with the saturation level of saliva, respectively, by using the resin plate and the glass was measured thickness and Spreadability. Methods: Examine the spreadability of denture adhesive in accordance with the saturation level of saliva, respectively, by using the resin plate and the glass was measured thickness and Spreadability. Also, by measuring the adhesive strength according to the amount of saliva, and the edentulous patients using denture adhesive and dry mouth patients attempt to provide clinical information of the denture adhesive. Therefore, by using the relatively low shrinkage cold curing resin, after fabricating specimen of plate form, for 7 days, it was immersed in water. Results: For the control group only denture adhesive, an artificial saliva for the experimental group were injected in $0.1m{\ell}$, $0.2m{\ell}$ and $0.3m{\ell}$ of the denture adhesive on the surface, experimental results of the investigation of the 10 times the tensile bond strength of the specimens in each group was obtained the following results. Conclusion: As the time to pressure increase in the same amount of saliva was found that the amount coming out of the denture adhesive, as the amount of saliva in the same pressure increase coming out of many denture adhesives. And the greater the pressure came out a lot of denture adhesives. Spreadability in measuring saliva contact with $0.1m{\ell}$ and $2m{\ell}$ and $3m{\ell}$ group pressured the diameter of the circular was the denture adhesive is small when compared to the group without adding the pressure of 2kg and 3kg put the saliva. The size of the circle is the same amount of saliva denture adhesive spread more pressure showed a greater increase.

• Tribology and Lubricants
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• 제38권3호
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• pp.73-83
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• 2022

This paper is concerned with an analysis of a surface edge crack emanated from a sharp contact edge. For a geometrical model, a square wedge is in contact with a half plane whose materials are identical, and a surface perpendicular crack initiated from the contact edge exists in the half plane. To analyze this crack problem, it is necessary to evaluate the stress field on the crack line which are induced by the contact tractions and pseudo-dislocations that simulate the crack, using the Bueckner principle. In this Part I, the stress filed in the half plane due to the contact is re-summarized using an asymptotic analysis method, which has been published before by the author. Further focus is given to the stress field in the half plane due to a pseudo-edge dislocation, which will provide a stress solution due to a crack (i.e. a continuous distribution of edge dislocations) later, using the Burgers vector. Essential result of the present work is the corrective functions which modify the stress field of an infinite domain to apply for the present one which has free surfaces, and thus the infiniteness is no longer preserved. Numerical methods and coordinate normalization are used, which was developed for an edge crack problem, using the Gauss-Jacobi integration formula. The convergence of the corrective functions are investigated here. Features of the corrective functions and their application to a crack problem will be given in Part II.

• 대한기계학회논문집A
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• 제32권4호
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• pp.354-361
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• 2008

Cold rolled steel sheet for automotive was treated by Ar/$O_2$ atmospheric pressure plasma to improve the adhesive bonding strength. Through the contact angle test and calculation of surface free energy for cold rolled steel sheet, the changes of surface properties were investigated before and after plasma treatment. The contact angle was decreased and surface free energy was increased after plasma treatment. And the change of surface roughness and morphology were observed by AFM(Atomic Force Microscope). The surface roughness of steel sheet was slightly changed. Based on Taguchi method, single lap shear test was performed to investigate the effect of experimental parameter such as plasma power, treatment time and flow rate of $O_2$ gas. Results shows that the bonding strength of steel sheet treated in Ar/$O_2$ atmospheric pressure plasma was improved about 20% compared with untreated sheet.

• Steel and Composite Structures
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• 제44권4호
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• pp.519-529
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• 2022

Sandwich structures with the superior mechanical properties such as high stiffness and strength-to-weight ratio, good thermal insulation, and high energy absorption capacity are used today in aerospace, automotive, marine, and civil engineering industries. These structures are composed of moderately stiff, thin face sheets that withstand the majority of transverse and in-plane loads, separated by a thick, lightweight core that resists shear forces. In this research, the finite element technique is used to simulate a sandwich panel with a truss core under axial compressive stress using ABAQUS software. A review of past experimental studies shows that the bondline between the core and face sheets plays a vital role in the critical failure load. Therefore, this modeling analyzes the damage initiation modes and debonding between face sheet and core by cohesive surface contact with traction-separation model. According to the results obtained from the modeling, it can be observed that the adhesive stiffness has a significant influence on the critical failure load of the specimens. To achieve the full strength of the structure as a continuum, a lower limit is obtained for the adhesive stiffness. By providing this limit stiffness between the core and the panel face sheets, sudden failure of the structure can be prevented.

• 한국정밀공학회지
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• 제33권3호
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• pp.231-234
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• 2016

Pouch film is manufactured by laminating aluminum foil, polyamide film and polypropylene film with an adhesive or extrusion resin. However, a surface treatment is required for the aluminum because bonding does not occur easily between the aluminum foil and the polymer film. Thus, for this study, surface treatment experiments were performed in order to confirm the effect on adhesion strength. First, a variety of surface treatment solutions were coated on aluminum foil, and contact angle and surface morphology analysis was carried out for the surface-treated aluminum. For lamination of the surface-treated aluminum foil with polyamide film, a polyurethane base adhesive was prepared for the adhesive strength test specimens. The adhesive strength between the aluminum foil and the polyamide film of the resulting specimens was measured (UTM). With such an experiment, it was possible to evaluate the effect on adhesive strength of the various surface treatments.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1997년도 제25회 춘계학술대회
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• pp.80-88
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• 1997

Repeated sliding contact wear test was performed with copper specimens to obtain the relationship between wear and surface hardening. Wear surface and wear track section were observed by optical microscopy. Wear volume and micro-vikers hardness of sublayer below wear surface were obtained. These results suggested that wear mechanism depended on contact load than sliding velocity. Therefore wear mechanism was abrasive wear within critical contact load and adhesive wear over critical contact load. Wear rate increased with contact load, sliding distance but decreased with sliding velocity. Surface hardening increased with sliding velocity and sliding distance but decreased with contact load.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제32회 추계학술대회 정기총회
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• pp.212-220
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• 2000

Single flighted screw extrusion is the most cost effective method for the production of film, sheet, pipe and the fundamental step in other processes including blow molding and injection molding. The temperature of polymer melts and injection pressure play a very important role in the injection molding machine. Thermal distortion and displacement of screw by temperature difference and injection pressure difference cause adhesive wear by metal-to-metal contact. In this paper we analyze thermal distortion and stress of screw includes pressure and temperature distributions by finite element analysis to understand dynamic characteristics of screw.