• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.27 no.3
• /
• pp.372-380
• /
• 2003

Impact tests were conducted to study the effect of angle ply and metal laminate on impact damage characteristics of Fiber Metal laminates (FML). Impact tests were conducted using drop weight impact machine and damage behavior were analyzed by comparing with load-displacement curve and surface observation and microscopic observation of cross sections. The effect of angle ply on impact characteristics of FML are influenced by property of metal laminate. i.e., when the metal laminate is not enough to strong to prevent fiber debonding, Angle ply FML is superior to singly oriented ply (SOP) FML because angle ply enhance the stiffness by fiber supports and prevent (rack propagation. However, when the metal laminate is enough to strong to prevent fiber debonding, SOP FML is superior to Angle ply FML because the fiber of lower ply in Angle ply FML are more stressed than that of SOP FML.

• Proceedings of the KSME Conference
• /
• 2001.11a
• /
• pp.204-209
• /
• 2001

In this research, the effects of fiber stacking sequence on damage behaviors of FML(Fiber Metal Laminates) subject to indentation loading. SOP (Singly Oriented Ply) FML and angle ply FML were fabricated to study fiber orientation effects and angle ply effects. FML were fabricated by using 1050 aluminum laminate and carbon/epoxy prepreg. To increase adhesive bonding strength, Al laminate was etched using FPL methods. The static indentation test were conducted by using UTM(5ton, Shimadzu) under the 2side clamped conditions. During the tests, load and displacement curve and crack initiation and propagation behaviors were investigated. As fiber orientation angle increases, the crack initiation load of SOP FML increases because the stiffness induced by fiber orientation is increased. The penetration load of SOP FML is influenced by the deformation tendency and boundary conditions. However, the macro-crack of angle ply FML was initiated by fiber breakage of lower ply because angle plies in Angle ply FML prevents the crack growth and consolidation. The Angle ply FML has a critical cross-angle which prevent crack growth and consolidation. Damage behavior of Angle ply FML is changed around the critical cross-angle.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.5
• /
• pp.960-968
• /
• 2002

In this research, the effects of fiber stacking sequence on damage behaviors of FML(Fiber Metal Laminates) subject to indentation loading. SOP (Singly Oriented Ply) FML and angle ply FML were fabricated to study fiber orientation effects and angle ply effects. FML were fabricated by using 1050 aluminum laminate and carbon/epoxy prepreg. To increase adhesive bonding strength, Al laminate was etched using FPL methods. The static indentation test were conducted by using UTM under the 2side clamped conditions. During the tests, load and displacement curve and crack initiation and propagation behaviors were investigated. As fiber orientation angle increases, the crack initiation load of SOP FML increases because the stiffness induced by fiber orientation is increased. The penetration load of SOP FML is influenced by the deformation tendency and boundary conditions. However, the macro-crack of angle ply FML was initiated by fiber breakage of lower ply because angle plies in Angle ply FML prevents the crack growth and consolidation. The Angle ply FML has a critical cross-angle which prevent crack growth and consolidation. Damage behavior of Angle ply FML is changed around the critical cross-angle.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.26 no.3
• /
• pp.21-28
• /
• 1989

The optimun laminated composition of the stiffened composite plates is studied from the view point of buckling strength. The finite element method is applied to the buckling analysis of the composite plates taking into account the effect of shear deformation through the plate thickness. The stiffened plate model is discretized using plate thickness and symmetrically stacked. Parametric study is carried out for the selection of the optimum laminate structure; optimum fiber angle sequence through the thickness. Laminate structure of $[-45^{\circ}/45^{\circ}/90^{\circ}/0^{\circ}]$, is found to give the best buckling strength. For the case of that layer number is more than eight, best result is obtained when layers of the same fiber angle are put together, leaving the laminate has the same fiber angle sequence as a whole.

• Journal of the Korea Convergence Society
• /
• v.10 no.1
• /
• pp.155-161
• /
• 2019

As composite is the light weight material whose durability and mechanical property are more superior than the existing general material. By taking notice of the composite with light weight, this study was about to investigate the static fracture characteristic of the bonded CFRP structure jointed with adhesive. Also, CFRP double cantilever beam with the variable of laminate angle was designed and the static fracture analysis was carried out. The laminate angles of CFRP double cantilever beam designed for this study were $30^{\circ}$, $45^{\circ}$ and $60^{\circ}$ individually. As the study result, the specimen with the laminate angle of $45^{\circ}$ was shown to have the durability better than those with the layer angles of $30^{\circ}$ and $45^{\circ}$. It was checked that the specimen with the laminate angle of $30^{\circ}$ had the weakest durability among all specimens. The damage data of the bonded CFRP structure by laminate angle could be secured through this study result. As the damage data of bonded interface obtained on the basis of this study result are utilized, the esthetic sense can be shown by being grafted onto the machine or structure at real life.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.15 no.1
• /
• pp.28-40
• /
• 1991

Affine transformation was used to analyze the bending, buckling and vibration behaviors of a thick antisymmetric angle-ply rectangular simply supported laminate. Introducing the generalized parameters, the comprehensive solutions are found. The generalized parameters are a generalized rigidity ratio ( $D^*1), a generalized Poisson's ratio (.epsilon.) and a principal rigidity ratio (.alpha.). Hence, the transverse deflection decreases, the uniaxial buckling load and the fundamental frequency increase with increasing $D^*1 and decreasing .alpha., but the effect of .epsilon. is negligible. With decreasing the thickness ratio, the results by the classical plate theory are more erroneous. The transverse deflection is minimum, the uniaxial buckling load and the fundamental frequency are maximum if the fiber angle is 45.deg., and number of plies is more than 4. The time and efforts can be saved to understand the behaviors of composite laminates because these results can be applied to another composite material easily.sily.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.10
• /
• pp.1824-1832
• /
• 1992

This study investigated the compressive Young's modulus and the impactinduced damage of CFRP angle-ply laminate under same impact energy condition. The specimens of angle-ply laminate composites [0.deg.$_{6}$/ .theta..deg.$_{10}$/ 0.deg.$_{6}$] with .theta..deg. =30.deg., 45.deg., 60.deg. and 90.deg. were employed, and damaged by steel balls of diameter of 5mm and 10mm propelled by air gun type impact testing machine. The impact damaged zones were observed through a scanning acoustic microscope(SAM), and their cross-sections were observed through a scanning electron microscope(SEM). The compressive Young's moduli before and after impact were measured, and compared with the theoretical values calculated. The results obtained were as follows: (1) The damage areas on the interfacial boundaries showed more severe change on the back side interface than on the impact side interface with increasing ply-angle. (2) The damage areas on the interfacial boundaries became larger with increasing impact velocity or ply-angle. (3) The impact damaged zone showed the delamination on the interfacial boundaries and transverse cracks inside laminas. (4) The impact damaged zone was affected by the impactor size and speed or ply-angle under same impact energy condition. (5) Compressive Young's moduli before and after impact were lower than theoretical value, but showed a similar change according to ply-angle. (6) Compressive Young's moduli after impact were higher than those before impact, but there was no remarkable change in apparent compressive modulus after impact.t.act.

• Structural Engineering and Mechanics
• /
• v.69 no.3
• /
• pp.327-334
• /
• 2019

The purpose of this paper is to investigate the hygrothermal effects on the behavior of reinforced-concrete beams strengthened by bonded composite laminate plates (${\theta}n/90m)s$. This work is based on a simple theoretical model to estimate the interfacial stresses developed between the concrete beam and the composite with taking into account the hygrothermal effect. Fibre orientation angle effects of number of $90^{\circ}$ layers and effects of plate thickness and length on the distributions of interfacial stress in the concrete beams reinforced with composite plates have also been studied.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.25 no.4
• /
• pp.58-68
• /
• 1988

This paper is concerned with mechanical properties of unidirectional laminate $[(0^{\circ})_{8T},\;(90^{\circ})_{8T}]$, composed of angle plies $[({\pm}15^{\circ})_{2S},\;({\pm}30^{\circ})_{2S},\;({\pm}45^{\circ})_{2S},\;({\pm}60^{\circ})_{2S},\;({\pm}75^{\circ})_{2S}$ and laminate $[(9^{\circ}/90^{\circ})_{2S},\;(90^{\circ}/{\pm}45^{\circ}/0^{\circ})_S,\;({\pm}45^{\circ}/0^{\circ}/{\pm}90^{\circ})_S,\;({\pm}45^{\circ}/90^{\circ}/0^{\circ})_S,\;(0^{\circ}/90^{\circ}/{\pm}45^{\circ})_S,\;(90^{\circ}/0^{\circ}/{\pm}45^{\circ})_S]$ under the condition of uniform strain tension. Also, experimental investigation was conducted $[10]_{8T}$, off-axis tensile test for intralaminar shear characterization. The experimental data on the failure criterion of tensor polynomial were compared with those from the classical laminate theory. Acoustic Emission experiments have been carried out to investigate the changes of the amplitude distributions of Acoustic Emission monitored during failure of tensile tests on Carbon/Epoxy composites.

• Elastomers and Composites
• /
• v.36 no.3
• /
• pp.195-200
• /
• 2001

Ultraviolet photografting of acrylic acid onto low density polyethylene was characterized using XPS and contact angle measurement. Effects of surface modification at LDPE and aluminum on LDPE/Al laminate were also investigated. Contact angle decreased significantly at initial state arid tends to level off with increasing UV irradiation time. The improvement of hydrophilicity was due to the presence of acrylic acid on LDPE surface. Graft of acrylic acid onto LDPE was also identified from O1s/C1s ratios in XPS spectrum. Adhesion strength of LDPE-g-AAc/Al laminate showed about 30 times higher than LDPE/A1 system and it could be attributed to the increase of polarity of LDPE surface. Chemical treatment of Al surface using sulfuric acid/sodium dichromate also increased the adhesion strength of LDPE/Al laminate. Adhesion strength of LDPE/Al laminate decreased significantly under acetic acid.