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Honeycomb sandwich composites are widely used in many industries. It is important to determine the impact strengths resulting from low-velocity impacts that sandwich composites may encounter in accordance with their intended use. In this study, the low-velocity impact performance of sandwich composites, which are combined with carbon fiber reinforced composite plates (CFRP) on the top and bottom surfaces of the cores produced from polylactic acid (PLA) filament in 3D printer, using honeycomb geometries with three different cell widths and cell wall thicknesses were investigated. Honeycomb geometries with three different cell widths and cell wall thicknesses of 6_0.8mm, 9_1.2mm and 12_1.6mm, respectively, were used in the study. In order to obtain equal surface area in samples exposed to low-velocity impact, these measurements were preferred by increasing both cell width and cell wall thickness. Low-velocity impact tests at five different energy levels (30J, 40J, 60J, 80J and 100J) were applied to honeycomb sandwich composite samples produced in dimensions in each geometry, and the sandwich composites were full perforated at 100J impact energy. Sandwich structures with the smallest cell width and the highest number of cells with 6mm cell width showed better performance against impact at 30J, 40J and 60J impact energy levels. With increasing impact energy, sandwich structures with three different cell widths at 80J and 100J energy levels were found to have similar performance against impact. [ABSTRACT FROM AUTHOR]

Today, 3-dimensional (3D) printers are developing increasingly, and rapid progress is being made to become an alternative to traditional production methods. 3D printers, which produce with the Fused Deposition Modeling (FDM) method, commonly produce by using polymer materials in the form of filament with a diameter of 1.75 mm or 2.85 mm. This study, tensile test specimens were produced using PLA filaments of different diameters (1.75 mm and 2.85 mm) with two different 3D printers. The electricity consumption of 3D printers during the production of tensile test samples was measured. The energy consumed by both 3D printers in producing tensile test specimens was compared. Instead of simultaneously producing a single test sample, it has been determined that the power consumption per test sample will be reduced by producing many test samples together. [ABSTRACT FROM AUTHOR]

Sandwich panel composites have a wide range of uses in material technology applications. The designed sandwich panel composite material; is made of stainless steel-316 as the top and bottom plate, aluminum 1050A-0 as the core material, and DP-8405 acrylic adhesive as the binding element. Three-point bending tests and finite element models investigated the bending behavior of S-core composite sandwich panels. Finite element models have been developed to characterize the effect of the bending behavior of composite elements on variations. The specific flexural modulus and strength of composite S-core sandwich structures can be compared with core structures in the literature. Accordingly, the minimum weight design provided a guideline for obtaining weight and density-efficient hybrid composite sandwich panels. When the damage loads in the test results were examined, it was concluded that the damage loads increased between 6.54% and 34.81% as the core thicknesses increased, and the damage loads decreased between 3.65% and 31.46% as the radius of curvature increased. [ABSTRACT FROM AUTHOR]

The properties of natural fibers such as poor ultraviolet (UV) resistance and hydrophilicity that reduce the durability of composites limit their usage as reinforcements in polymer matrix composites. To compensate this, new types of composites are proposed in the present study. The tribological behaviors of multiphase composites with polyaspartic polyurea matrix produced by vacuum assisted resin transfer molding (VARTM) technique with jute reinforced, filled by graphene nanoplatelets (GNPs) and titanium dioxide (TiO2) nano-fillers at high temperatures are investigated. The wear tests were performed under 10, 20, and 30 N loads, at 60% humidity and temperatures of 100°C, 125°C, and 150°C using a heat moduled pin-on-disc tribotester with an AISI 4140 counter-surface disc having an average surface roughness value of 1.033 µm. The tests were carried out under dry friction conditions along 6000 m sliding distance at a sliding speed of 2 m/s. The results show that the wear damage types changed according to the nano-filler type. Wear loss and specific wear rate increased with increasing temperature and load in almost all types of composites. Using nano-filler caused irregularities in the change of the friction coefficient. [ABSTRACT FROM AUTHOR]

In this study, tensile test specimens have been produced using ABS (acrylonitrile butadiene styrene) and PLA (poly-lactic acid) material at different printing speeds (20-40-60-80-100-120-140mm/s) with Ultimaker 2 Extended 3D printer. The effect of printing speed on mechanical properties has been investigated. Masses, hardness and surface roughness of the produced samples have been measured, porosity values have been calculated and tensile test has been performed on the produced samples. After the tensile test, images have been taken by scanning electron microscopy (SEM) from the breaking regions of the broken samples. The mechanical properties of the samples produced with the same parameters with both materials have been compared. As a result; it has been determined that the tensile strength of the samples produced with PLA material are higher than the samples produced with ABS material, and the elongation at break values of the samples produced with ABS material are higher than the samples produced with PLA material. [ABSTRACT FROM AUTHOR]

• S-core sandwich panel composites design and manufacturing were done. • Finite element modeling and mechanical tests were performed in three-point bending. • Bending behaviors were compared. Sandwich panel composites have numerous applications in material technology. The sandwich panel composite structure's mechanical behavior and performance are determined by the material properties and geometry of the relevant components. The top and bottom sheets of the designed sandwich panel composite material are made of stainless steel-316, the core material is aluminum 1050A-0, and the binding element is DP-8405 acrylic adhesive. Three-point bending tests and finite element models were utilized to investigate the bending behavior of S-core composite sandwich panels. Finite element models have been developed to characterize the effect of composite element bending behavior on variations. The specific flexural modulus and strength of composite S-core sandwich structures can be compared to core structures in the literature in general. As a consequence, the minimum weight design was used as a guideline to produce weight and density-efficient hybrid composite sandwich panels. The load-carrying capacity of the composite panel increased as the wall thickness of the S-shaped core increased when the damage loads were examined in the variations. It has been ascertained that as the core height increases, the load-carrying capacity of the composite panel decreases. [ABSTRACT FROM AUTHOR]

In recent years, natural fiber reinforced composites have become an alternative to synthetic fiber reinforced composites in some areas due to their properties like low cost, biodegradability and lightness. In this study, abrasive wear tests were applied to jute fabric reinforced epoxy matrix composites filled with graphene nanoplatelets (GNPs) at different filling ratios (0, 0.5, 1, 2 wt.%), produced with vacuum assisted resin transfer molding (VARTM) method. Tribotests were carried out using a pin-on-disk type tribotest device on the counterface of 400 grit SiC emery paper with 5 N, 10 N and 15 N loads at a sliding speed of 1 m s-1 and a sliding distance of 200 m. In the tests carried out, the interface temperature and specific wear rate values were followed. It has been found that the specific wear rate is minimal at 1 wt.% GNPs filler and the interface temperature generally increases with increasing load. [ABSTRACT FROM AUTHOR]

In this work, elasto-plastic stress analysis of single lap joints with and without protrusion in adhesive bondline subjected to tension and bending was carried out using 2D non-linear finite element analysis and confirmed experimentally. AA 2024-T3 aluminum adherends were bonded with SBT 9244 film adhesive. The protrusion was obtained by extending the adhesive film by 2 mm from the overlap length at both overlap ends. Three different adher-end thicknesses and overlap lengths for each loading and bondline type were used. The joints with and without protrusion, for comparison, were loaded with the same load for each adherend thickness and overlap length. Finally, it was observed that the protrusion reduces the strength in the joint under tension, while the protrusion increases the strength in the joint under bending. [ABSTRACT FROM AUTHOR]

In this study, stress analysis of double-strap joints used to fasten parts, particularly in aircraft and automotive industries and in the repair of damaged parts, was done using the finite element method. In classical double-strap adhesive joints, patch parts are bonded to the outer surface and these parts resist air flow. To decrease this effect and for constructive and aesthetic requirements, patch parts were embedded into the adherends. The effects of embedded patch parts on failure loads and stress distributions were investigated experimentally and numerically. For this purpose, AA 2024-T3 aluminum adherends with four different thicknesses (4.8, 5.6, 6.4 and 7.2 mm) were bonded as double patches with 0.4, 0.8 and 1.2 mm spring steel patch thicknesses and 20, 40 and 60 mm overlap lengths. The stress analyses were done under plain strain assumption. To verify the finite element model, experiments were carried out. The results show that adherends and patch thicknesses as well as overlap length all have considerable influence on failure loads and stress distributions. [ABSTRACT FROM AUTHOR]

Abstract: The stresses and deformations in the shrink-fitted hub–shaft joint for various fit forms have been analysed using finite element method. First, the results of finite element method (FEM) were compared with the results of Lame’s equations along central radial line of one shrink fit type for accuracy of model and it was proved by these results. Then, the most appropriate fit type was investigated. It was observed that the most effective parameter to determine appropriate fit type is to be stepped or not for shaft and the geometries of hub of which edges were wasted have been found as more appropriate to reduce the stresses and deformations. Finally, it was also observed that the each point of the shaft or the hub at the moment of the first meeting to its partner during fit can enter the plastic region, and this situation must be taken into consideration as design parameter. [Copyright &y& Elsevier]

The use of adhesive bonding as fastener presents very high usage potential, especially for different environments. However, the designers do not have enough data yet to address the changes in the mechanical properties of adhesives in the course of time. In this study, the ageing of film-type adhesives, Structural Bonding Tapes (SBT) 9244 and 9245, which are different in thickness and possess pressure-sensitive and visco-elastic properties, was investigated. First, the bulk adhesive specimens were prepared and exposed to two different environmental conditions until saturated. In the same time, single lap joints with two different adhesive layer thicknesses, consisting of AA2024-T3 as the adherend, were exposed to the same environmental conditions for exposure times of 90 days. The immersion environments were 100% relative humidity (RH) and 3.5% NaCl solution. At the end of exposure time, the failure surfaces were examined by Scanning Electron Microscopy (SEM) after the strength of joints was determined with the lap shear test. Both SBT adhesives absorb more water from 100% RH than from 3.5% NaCl solution and, therefore, they deteriorate rapidly in 100% RH. In addition, as the thickness of adhesive layer increases, the loss in the strength increased. [ABSTRACT FROM AUTHOR]

Powder mixing is a significant step in the manufacturing process of many industrial products such as pharmaceuticals, foodstuffs, plastics, fertilizers, and ceramics. Especially in recent years, with the development of material technology, the importance of powder mixers has increased. But dynamic characteristics of powder mixer is very complex problem. In this paper, a Turbula type mixer has been modeled with the Solidworks® and its nonlinear transient response was investigated by the Finite Element Method (FEM). Finite element analysis (FEA) was used to determine the transient response of the vessel and stirrups under different load conditions. The transient analysis is carried out for different rotation speeds (30, 45, and 60 rev/min) of powder mixer and equivalent stresses on vessel and stirrup were obtained. In addition, 1, 3 and 5 kg mass added to the vessel homogeneously in order to obtain the influence of added mass (represent the powder mass). Results revealed that with increasing rotation speed and added mass, the equivalent stress in the vessel and stirrups increased. Maximum stress occurred in the joint of stirrup and vessel. Commercial software ANSYS Workbench (version 19.2) and nonlinear ANSYS® Mechanical APDL solver have utilized for transient response of powder mixer. [ABSTRACT FROM AUTHOR]

Abstract In this study, single lap joints were formed by adding nano-Al 2 O 3 , nano-TiO 2 and nano-Al 2 O 3 powders in various proportions to the epoxy adhesive and using the additive-free epoxy adhesive; and also the mechanical properties of the connections were experimentally investigated at 20, 25, 30, 50 and 70 mm overlap lengths under shear load. In the experimental work, DP460 epoxy adhesive was used as adhesive and AISI 304 stainless steel plate as adherent material. When the results obtained from the experiments were examined, it was revealed that the average damage load in connection with the use of nanoparticle-added adhesives increased considerably in general. As a result of the experiments, the most effective nanoparticle in increasing the failure strength of the adhesive joints with nano-Al 2 O 3 particles and the maximum failure strength increase rate was 20 mm in overlap length and 97% in 4 wt% nano-Al 2 O 3 reinforced specimens. It was also found that the nanoparticle strain was an important parameter in the tensile strength of the adhesive joints. In addition, it has been found that the addition of nanoparticles into the adhesive increases the elongation of the joints. When the adhesion surfaces of the samples were examined as in the case of plain adhesives, damage was observed as adhesion separation while nanoparticle reinforcement was observed as a mixture of adhesion and cohesion. Graphical abstract Image 1 Highlights • Behaviour of nano-particle used in the adhesive joints was analyzed by experimental. • The effects on the tensile strength of nano-particles were investigated in single lap joints added nano-particle. • Three type nano-particles are used to mix with adhesive. • Experimental analyses were carried out to predict the failure loads. • The maximum failure strength increase rate was 20 mm in overlap length and 97% in 4 wt% nano-Al 2 O 3 reinforced specimens. [ABSTRACT FROM AUTHOR]

Abstract Because of their many advantages, adhesively bonded joints are intensively used in many engineering fields. So, the mechanical research of the adhesively bonded joints is very important to use these joints safely. There are many studies performed by researchers to investigate the mechanical properties of the adhesive joints. There has been a considerable interest in nanoparticles added to structural adhesives recently because nanoparticles improve the mechanical properties of adhesives and joints. In this paper, different nanoparticles reinforced by epoxy adhesive, and neat adhesive were used to produce single lap joints. The static and fatigue strengths of single lap joints incorporating nanoparticles were compared to those without nanoparticles. Experiments were performed at 20 mm overlap length. DP460 epoxy was used as the adhesive material, and nano-Al 2 O 3 , nano-TiO 2 and nano-SiO 2 were used as the nanoparticles; and AISI 304 stainless steel plates were used as the adherents. The results of the experimental research revealed that average failure load increased significantly in nanoparticle-reinforced adhesive joints. The highest average failure load was obtained with 4 wt% nano-Al 2 O 3 in epoxy adhesive. Fatigue tests were performed at 10 Hz frequency, and 0.1 loading ratio (R). When the fatigue test results were examined, it was observed that the addition of the nano-Al 2 O 3 and nano-SiO 2 to the adhesive increased fatigue strength of the adhesive joints, on the other hand, the addition of the nano-TiO 2 to the adhesive reduced fatigue strength of the adhesive joints. Graphical abstract Image 1 Highlights • Behavior of nano-particle used in the adhesive joints was analyzed as experimental. • The effects of nano-particles were investigated in the single lap joints on the static and fatigue strength. • Three type nano-particles are used to mix with adhesive. • The highest average failure load was obtained with 4 wt% nano-Al 2 O 3 in epoxy adhesive. • It was observed that the addition of the nano-Al 2 O 3 and nano-SiO 2 increased fatigue strength of the adhesive joints. [ABSTRACT FROM AUTHOR]

Accidents in the industry, especially in the field of aerospace, are quite common. Damages like tears cracks and holes occur especially when small sand particles present in the airfield collide with the body and wings of an airplane during takeoff and landing. This torn, cracked, or pierced region should be repaired gently. Damaged parts are frequently small regions for which repair is more suitable than complete replacement as workmanship; cost and time are an important concept in today’s world. A gap occurs between the patches if double-bonded patches are used in the repair of the damaged parts. In this study, the region between patches in a joint with and without intermediate parts was modeled and its effect on strength was examined numerically and experimentally. The effects of patch thickness, overlap length, adherent thickness, and gap length on the strength of the joints with and without intermediate part was compared. The results show that the intermediate part does not have any influence on the strength of the lap joint such that double strap joints without intermediate part have higher failure load. Additionally, it is seen that the failure load decreased with increasing patch thickness and increased with the thickness of the adherent. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, it is aimed to compare mechanical behaviors of T-joint types with embedded and non-embedded supports subjected to bending moment. For this purpose, after experimental studies on the two different T-joint types were conducted, stress analyses in the T-joints were performed with a three-dimensional finite element method by considering the geometrical non-linearity and the material non-linearities of the adhesive (DP460) and adherend (AA2024-T3). Finally, stress analyses and experimental results show that the variation of the geometry of the bonding zone, e.g., embedding the supports, would change the stress distributions and strength of the joint. Additionally, it is seen that T-joints with embedded supports carry 30% more load than T-joints with non-embedded supports although their bending stiffnesses decrease. [Copyright &y& Elsevier]

This paper presents an approach to predicting the failure and strength of joints bonded with a film-type adhesive (FM 73) using non-linear finite element method. First, lap-shear tests on Single-Lap Joints (SLJs) with different adherend thicknesses and overlap lengths were carried out and fracture surfaces of the SLJs were examined by scanning electron microscopy (SEM). Then, the stress analyses in the SLJs using a non-linear finite element method were performed by considering both the geometrical non-linearity and non-linear material behaviors of both adhesive and adherend (AA2024-T3), and Finite Element Analysis (FEA) results were compared with experimental results. Two different failure loci were seen when the failure surfaces of the SLJs were examined and both the stress analyses and experimental results showed that a catastrophic failure occured around the central zone of the overlap due to the effect of shear stresses, while the failure at the free edges of the adhesive layer originated from the peel stress in tension. [ABSTRACT FROM AUTHOR]

In this work, elasto-plastic stress analysis of a Single Lap Joint (SLJ) subjected to bending moment was investigated using 2D non-linear Finite Element Analysis (FEA). The SLJs, consisting of hardened steel as the adherend bonded by two adhesives, one stiff and one flexible, with very different mechanical behaviors were analyzed. In order to determine the effect of geometrical parameters on the performance of the SLJs, four different adherend thicknesses and overlap lengths for each adhesive were used. For verification of the analysis, the FEA results were compared with experimental results. It was observed that there was a significant effect of adherend thickness on the strength of the joint with both adhesives. However, the load carried by the SLJ with the flexible adhesive increased with increasing overlap length. [ABSTRACT FROM AUTHOR]

Abstract: In this study, mechanical properties of adhesively bonded single-lap joint (SLJ) geometry with different configurations of lower and upper adherends under tensile loading were investigated experimentally and numerically. The adherends were AA2024-T3 aluminum and carbon/epoxy composite with 16 laminates while, the adhesive was a two-part liquid, structural adhesive DP 460. In experimental studies, four different types of single-lap joints were produced and used namely; composite–composite (Type-I) with lower and upper adherends of the same thicknesses and four different stacking sequences, composite–aluminum (Type-II) with lower and upper adherends of the same thicknesses and four different stacking sequences, composite–aluminum (Type-III) with lower adherend (composite) of the same thickness but upper adherend of three different thicknesses, aluminum–aluminum (Type-IV) with lower adherend of the same thickness but upper adherend of three different thicknesses, composite–composite (Type-V) with [0]16 stacking sequences and three different overlap length, aluminum–aluminum (Type-VI) with three different overlap length. In the numerical analysis, the composite adherends were assumed to behave as linearly elastic materials while the adhesive layer and aluminum adherend were assumed to be nonlinear. The results obtained from experimental and numerical analyses showed that composite adherends with different fiber orientation sequence, different adherend thicknesses and overlap length affected the failure load of the joint and stress distributions in the SLJ. [Copyright &y& Elsevier]