Tensile Adhesion Strength Research Articles

Strength analysis due to thermal loading and tensile loading when metals are bonded by heat-curing adhesives

Heat-curing adhesives are widely used after being cured by heating to a temperature higher than room temperature. To evaluate the adhesive strength, therefore, it is necessary to consider both the thermal stress generated during heat curing and external loads such as tensile stress. Butt joint specimens are essential for evaluating tensile adhesive strength but also thermal strength. The interfacial strength can be discussed from the stress intensity factor (SIF) of a fictitious edge interfacial crack assumed at the interface end. This is because the SIF is controlled by the intensity of singular stress field (ISSF) at the crack-free interface end and a constant term associated with the thermal load. In this paper, a useful thermal SIF solution is proposed by superposing the SIF under tensile stress and the SIF under uniform interface stress associated with thermal loading. This general SIF expression provided under arbitrary material combination can be applied for predicting the tensile strength σc and critical temperature change ΔT without performing new FEM calculations. The usefulness of the expression is confirmed through the adhesive strength of Aluminum/Epoxy butt joint experimentally obtained. Once the critical SIF K1C can be obtained from the tensile strength σc and the temperature change ΔT, the adhesive strength can be expressed asK1C = constant of an assumed fictitious interface, and this can be used to predict critical σc for various temperature change ΔT and for various adhesive bondline thickness h.

Waste From Alwar Quartzite (A Global Heritage Stone From Rajasthan - India) As Secondary Raw Materials for Cementitious Tile Adhesives

Waste deriving from quarrying operations of natural stone material retains almost all the mineralogical and compositional characteristics of the original material, for such reason this research aimed to test prototypes cementitious tile adhesives made up recycling the Alwar Quartzite waste, used as fine and ultra-fine aggregate. Particle size distribution analysis, along with X-ray diffractometry, X-ray fluorescence and Scanning Electron Microscopy were carried out to characterize the waste. Experimental research involved the mix-designing of three dough formulations (a regular one [N], a latex added [L] and a fast-setting [R]) tested by using different types of tiles: (i) polished metal plates, (ii) ceramic tiles and (iii) rough natural stone slabs. Fresh prepared doughs were firstly tested for thixotropy achieving high values (ranging 82–93%) and cured for normative requested time after being stuck on a concrete support as reported in European UNI standard regulations. After respective curing time, adhesives technical performances were evaluated by the Pull-Off test obtaining results for Class 1 (N and R) and Class 2 (L) adhesives with high initial tensile adhesive strength. Experimental results carried out in this research proved the possibility to use huge amounts of waste coming from Indian stone industry in cementitious tile adhesives sector without compromising technical performances, proposing itself as an alternative method to landfill disposal for this waste.

Strength Enhancement of Polyurethane Film by Solution Annealing.

Recently, polyurethane elastomer (TPU) has attracted more and more attention depending on its excellent optical, mechanical, and retreatment properties. The high strength of polyurethane has always been pursued, which can enable its application in more fields. In this work, an aliphatic polyurethane elastomer membrane (HRPU6) was successfully synthesized, and its strength was obviously improved by solvent annealing technology. The tensile strength and adhesion strength can reach 64.56 and 2.58 MPa, but 36.55 and 1.57 MPa only before solvent annealing, respectively. The impact strength of laminated glass based on HRPU has also been significantly improved after solvent annealing, confirmed through drop ball impact testing. It has been confirmed that the increase in strength of HRPU6 is attributed to the enhancement of hydrogen bonding and the improvement of the phase separation degree.

Tensile strength of adhesives in peripheral nerve anastomoses: an in vitro biomechanical evaluation of four different neurorrhaphies

BackgroundThe fundamental prerequisite for prognostically favorable postoperative results of peripheral nerve repair is stable neurorrhaphy without interruption and gap formation.MethodsThis study evaluates 60 neurorrhaphies on femoral chicken nerves in terms of the procedure and the biomechanical properties. Sutured neurorrhaphies (n = 15) served as control and three sutureless adhesive-based nerve repair techniques: Fibrin glue (n = 15), Histoacryl glue (n = 15), and the novel polyurethane adhesive VIVO (n = 15). Tensile and elongation tests of neurorrhaphies were performed on a tensile testing machine at a displacement rate of 20 mm/min until failure. The maximum tensile force and elongation were recorded.ResultsAll adhesive-based neurorrhaphies were significant faster in preparation compared to sutured anastomoses (p < 0.001). Neurorrhaphies by sutured (102.8 [cN]; p < 0.001), Histoacryl (91.5 [cN]; p < 0.001) and VIVO (45.47 [cN]; p < 0.05) withstood significant higher longitudinal tensile forces compared to fibrin glue (10.55 [cN]). VIVO, with △L/L0 of 6.96 [%], showed significantly higher elongation (p < 0.001) compared to neurorrhaphy using fibrin glue.ConclusionWithin the limitations of an in vitro study the adhesive-based neurorrhaphy technique with VIVO and Histoacryl have the biomechanical potential to offer alternatives to sutured neuroanastomosis because of their stability, and faster handling. Further in vivo studies are required to evaluate functional outcomes and confirm safety.

Performance evolution of epoxy adhesive and CFRP-steel epoxy-bonded joints subjected to hygrothermal exposure

Carbon fiber-reinforced polymer (CFRP)-steel epoxy-bonded joints are widely used in civil, mechanical, and railway engineering structures. However, the mechanical and bonding performance of the epoxy adhesive is sensitive to hygrothermal exposure, which may lead to performance degradation of CFRP-steel bonded interfaces. In this study, the performance evolution of epoxy adhesives and CFRP-steel epoxy-bonded joints after hygrothermal exposure was investigated. Three hygrothermal exposure temperatures (25 °C/50 °C/75 °C) and three hygrothermal exposure times (24 h/120 h/360 h) were considered. The dynamic mechanical behavior and tensile properties of the bulk adhesives were studied by dynamic mechanical analysis (DMA) and tensile tests, respectively. Additionally, the mechanical failure properties of the bonded joints, including failure mode, strain distribution, and bond-slip relationship were obtained by tensile tests. The results indicated that the glass transition temperature (GTT) and tensile strength of adhesive J133 are always higher than those of A2014 in all test scenarios. The interface remains the weakest after hygrothermal exposure. After the 50 °C hygrothermal exposure, both CFRP-steel joints possess the highest bond strength and interfacial maximum bond stress, which corresponds to their higher adhesive tensile strength at the same temperature. In addition, we also find that both CFRP-steel joints show an increase in bond strength after short-term hygrothermal exposure.

Evaluation of mechanical properties of cement mortars containing pond ash as partial replacement of river sand and prediction of properties by regression models

Despite vast research on the utilisation of coal ashes in cement mortars, many studies lack a comprehensive evaluation of properties related to mortar for masonry and plaster work. This study investigate properties like workability, compressive strength, drying shrinkage, tensile bond strength and adhesive strength through a systematic replacement of river sand by pond ash in cement mortars. Volumetric mix proportions of 1:3, 1:4, 1:5 and 1:6 (cement: sand) were considered, where river sand was replaced in the range of 20–100% by pond ash. At 30% pond ash content, properties like the compressive strength, tensile bond strength and adhesive strength improved in the range of 21–30%, 13–20% and 14–24%, respectively, for all mix proportions. At 60% pond ash content, these strength properties were comparable with those of control mixes and found suitable for mortars for masonry works. However, the drying shrinkage increased with an increase in pond ash content. At 30% pond ash content, drying shrinkage increased in the range of 26–40% for all mix proportions. The thermogravimetric analysis (TGA) showed that mixes with pond ash demonstrated reduced portlandite content compared to the control mixes, resulting in the formation of secondary C-S-H gel. Simple regression models were developed based on experimental results to establish the relationships between different properties. Based on coefficient of determination (R 2), variance inflation factor (VIF) and Durbin–Watson statistics, relationships between the strength and shrinkage properties were very well quantified to be used by researchers and practitioners. Utilisation of pond ash as partial replacement of river sand in mortars proved to be a useful step towards achieving circular economy at the same time reducing threat to depletion of limited natural resources.

Improved tribological performance and enhanced tensile adhesive strength of micro- to near-nanocrystalline WC-17 wt. %Co coatings sprayed using HVOF

This study investigated the performances of micro- and near-nanocrystalline coatings of WC-17 wt.% Co applied to a steel substrate using the high-velocity oxy-fuel (HVOF) spraying method. The near-nanocrystalline coatings exhibited reduced decarburization, as shown by the XRD and Rietveld refinement analyses. SEM analysis revealed small grain size, low porosity, and uniform surface texture in the near-nanocrystalline coatings. These coatings exhibited superior properties, including a high hardness (∼1298 HV), high tensile adhesive strength (≈9890 PSI), low wear rate (∼0.0011 mm3/m), and minimal wear volume loss (∼0.022 mm3), surpassing microcrystalline coatings. Near-nanocrystalline coatings exhibited 52.17 % less wear volume loss, attributed to factors such as smaller particle size, denser coating structure, reduced porosity, limited decarburization, and the high hardness of near-nanocrystalline coatings. Triboscopic analysis further confirmed their exceptional wear resistance, low wear volume loss, and low coefficient of friction, suggesting that near-nanocrystalline coatings could be effective for protecting substrates in demanding critical conditions, align with the Boeing Standard BSS 7072 requirements, and hold promise as robust surface protection solutions.

Avaliação do desempenho de argamassas autonivelantes utilizando resíduos de fosfogesso e cerâmica branca

Abstract This study investigates the properties of self-leveling subfloor mortar mixtures with natural and calcined phosphogypsum waste in the form of calcium sulfate called anhydrite and white ceramic, by replacing 50% of the mass of Portland cement CP II Z-32. The effects of using waste were evaluated in the fresh (initial fluidity, flow retention, regeneration time, setting time, and heat of hydration) and hardened (compressive and flexural tensile strength, density, water absorption, void ratio, linear shrinkage, and tensile adhesion strength) state. The optimized mixture at a 1:1.5 cement/sand ratio (by mass) with 50% white ceramic had a 32.66 ± 4.26 MPa compressive strength at 28 days, low shrinkage and heat of hydration, showing the best performance among the wastes studied. In the calcium sulfate mortars, the mixtures with anhydrite showed better results for compressive and flexural tensile strength and tensile adhesion strength, with the waste calcination being beneficial.

Autogenous Self‐healing of CTRC Repair Layers Exposed to Tensile Threshold Loading

AbstractThe experimental investigations presented in this paper contribute to fill the knowledge gaps on the subject of autogenous self‐healing of DURTEX layers for the surface repair of cracked or cyclic crack opening of concrete and reinforced concrete structures. Composite specimens, so‐called crack distribution specimens, were subjected to at least 1000 and up to 6900 cycles. Investigations show that neither the crack characteristics (e. g. crack width, crack geometry) change nor the mechanical properties (e. g. adhesive tensile strength or tensile load‐bearing behavior) are reduced compared to the reference specimens as a result of cyclic loading with both pore and crack water pressure. Also, the self‐healing potential of a selected material combination is demonstrated despite cyclic loading. It was observed that cracked DURTEX layers with wmax = 0.116 mm, under cyclic loading (Δwop = 0.6 mm) at a constant test speed set to 0.05 mm/min (piston controlled) with a 5 m pore and crack water pressure can self‐heal themselves leading to water tightness after 14 days. Chemical‐mineralogical analysis using X‐ray diffraction (XRD) on material taken from the cracked surface of the specimen evidenced the formation of CaCO3 as calcite.

Synthesis of polyurethane hot melt adhesive without solvent via Diels-Alder reaction

Polyurethane hot melt adhesive was synthesized without any solvent via Diels-Alder (DA) reaction between furan terminated prepolymer and bismaleimide (BMI) and was coded as PU-DA-NS. Firstly the DA reaction was inhibited at higher temperature (110 °C) to reduce the viscosity and benefit the contact of furan terminated prepolymer and BMI. Consequently, PU-DA-NS was obtained via DA reaction at lower temperature (70 °C). The structure of PU-DA-NS was investigated via 1H NMR, DSC and TGA. The results showed that the solvent-free preparation cannot reach the reaction degree of solvent preparation, due to the contact of the reactants cannot be as good as preparation in solvent such as DMF, although the higher temperature decreased the viscosity of the reactant. However the heating and pressing procedure during the adhesive process destroyed the looser structure and increased the adhesive tensile strength to 70 % of PU-DA synthesized via solvent preparation.

Aryloxyphosphazene-Modified and Graphite-Filled Epoxy Compositions with Reduced Flammability and Electrically Conductive Properties

A method has been developed for producing an epoxy composition based on a low-viscosity epoxy-resorcinol resin, a phosphazene-containing curing agent, isophoronediamine, and thermally expanded graphite as a filler. The degree of cure and the absence of side reactions during the curing process were confirmed using IR spectroscopy. The influence of the content of phosphazene-containing curing agent and filler on the physico-mechanical properties of the composition, its fire resistance, and antistatic properties were studied. Using the UL-94 HB horizontal burning test, it was found that the addition of 10 and 20 wt. % phosphazene-containing curing agent (relative to isophoronediamine) reduces the burning speed by 10 times compared to a sample without phosphazene. The addition of a filler to a composition containing phosphazene reduces the burning speed by 25 times compared to a composition without phosphazene and imparts antistatic properties to the epoxy composition, as evidenced by the specific volume electrical resistance of the order of 101 Ohm·m. Phosphazene-containing curing agent had no statistically significant effect on specific volume electrical resistivity (p &gt; 0.05). Tests of physico-mechanical and adhesive properties (tensile strength, compressive strength, water absorption, water solubility, abrasion resistance, and adhesive strength) of filled epoxy compositions with 10 and 20 wt. % phosphazene-containing curing agent demonstrated that these properties met the requirements for floor coverings in construction and parts of electrical devices.

Using of microsilica for improvement of physical and mechanical properties of epoxide-based composite material

Utilization of industrial waste and secondary raw materials, in particular, in the production of metallic silicon and silicon-containing alloys, which include silica vapors (microsilica), is the main task of implementing environmental policy and solves the problem of their storage and negative impact on the environment, in order to reuse them in polymer composites. The use of microsilica as a filler in composite materials based on epoxy resins contributes to a positive effect on the basic properties of the resin, and also makes it possible to use the composite material as coatings and parts in the repair of machinery and equipment. The aim of the work was to establish the positive effect of microsilica as a filler in composite materials based on ED-20 epoxy resin on improving the physical and mechanical properties of composite materials. Within the framework of this work, studies were conducted to test composite materials based on ED-20 epoxy resin, differing in different filler content of 2, 5, 10, 15 wt. % on impact strength, tensile strength and modulus of elasticity, adhesion and impact strength of the coating. The analysis of the obtained results showed a positive effect of microsilica as a filler in composite materials based on ED-20 epoxy resin on the physical and mechanical properties of the composite material. The optimal filler content was determined, which is 2 % of the mass of the ED-20 epoxy resin, while an increase in adhesion, toughness of the composite material by 45 %, tensile strength and modulus of elasticity by 21 % and 5 %, respectively, and the strength of the coating on impact by 32 %, compared with the addition of microsilica in ED-20, which shows the prospects of using microsilica as a filler in composite materials

Optimization of Segmented Thermal Barrier Coatings (s-TBCs) for High-Temperature Applications

AbstractHot section components of stationary gas turbines, such as turbine blades and vanes, are coated with thermal barrier coatings (TBCs) to increase the component life. TBCs provide thermal insulation to the metallic components from hot gas in the gas turbines. The TBCs represent high-performance ceramics and are mainly composed of yttria-stabilized zirconia (YSZ) to fulfill the thermal insulation function. The microstructure of the TBCs should be porous to decrease heat conduction. Besides the porous TBCs, the subsequently developed vertically segmented thermal barrier coatings (s-TBCs) feature outstanding thermal durability. For the formation of this segmented coating microstructure, the YSZ should be deposited under high thermal tensile stress during the coating process. Therefore, substrates are heated just before the coating by plasma or in an oven in recent research. In this work, the development of process parameters for s-TBCs produced by atmospheric plasma spray (APS) without pre-heating is presented. Within the experiments, the relevant process parameters, such as plasma gases, powder feed rate, surface speed, and pathway strategy, have been optimized to achieve the segmented coating microstructure with high deposition efficiency by a conventional plasma torch. Furthermore, YSZ powders used in this study are characterized, and the effect of powder characteristics on the coating microstructure is investigated. The coating microstructure in this work aims to achieve the formation of a high number of vertical cracks with a combination of low internal residual stress and high adhesive tensile strength for the s-TBCs.

Application of Vietnamese Nano Graphene as SBR Rubber Reinforcement for Abrasion Resistance Conveyors

Graphene has been extensively considered as an ideal additive to improve the mechanical properties of many composite materials, including rubbers, because of its novel strength, high surface area, and remarkable thermal and electron conductivity. Styrene Butadiene Rubber (SBR) is considered a good material for abrasion resistance conveyors in industries. However, the mechanical properties of SBR still need to be improved. This study shows the enhancement of Vietnamese nano graphene (GNPs) on mechanical properties of SBR rubber such as tensile strength, tear strength, abrasion resistance, and adhesion strength. The distribution of the Dioctyl Phthalate (DOP)-modified GNPs in the SBR matrix was investigated using scanning electron spectroscopy. Results show a significant increase in SBR/GNPs nanocomposite mechanical properties with the presence of GNPs (tensile strength, and tear strength increased by 29.67% and 31.89% respectively in comparison with SBR rubber without GNPs, and abrasion weight loss was decreased by 30.84% in comparison with SBR and adhesion strength with polyester fabric was 3 times higher than that of SBR). The evaluation of GNPs content in SBR/GNPs nanocomposite material was carried out. Results show that 0.5 phr of GNPs content in SBR/GNPs nanocomposite material was the optimal GNPs content with good mechanical properties, high abrasion resistance, and good adhesion with polyester fabric.

Impact of Preceded Tumor Therapeutic Irradiation on the Microtensile Bond Strength of Universal Adhesives Applied in Self-Etch Mode to Human Dentin In Vitro

The aim of this study was to investigate the effect of preceded tumor therapeutic irradiation on the tensile bond strength of three modern universal adhesives applied in self-etch mode on dentin. Specimens prepared from 135 extracted human third molars were divided into three superior groups. These received either no radiation, 5 Gy, or a total dose of 60 Gy in vitro irradiation, fractionally applied. The samples of each group were further randomly assigned to six subgroups to test three adhesives (Futurabond® U, Voco; AdheSE® Universal Ivoclar Vivadent; Xeno® Select, Dentsply Sirona) in the self-etch application mode (n = 15). Tensile bond strength was determined using a universal testing machine (1.0 mm/min). Data were analyzed with ANOVA (p &lt; 0.01) and Tukey’s test (p &lt; 0.05). The influence of irradiation on the microtensile bond strength of the used dentin adhesives proved to be significant. For each material, a decrease in adhesion value was registered after irradiation. However, only for the material Xeno® Select were significantly reduced adhesion values determined after irradiation with 60 Gy compared to 0 Gy. Within the limitations of an in vitro study, some effects of tumor therapeutic irradiation of human dentin on the tensile bond strength of universal adhesives used in self-etch mode could be observed. Those decreases were only partly significant, depending on the material and the radiation dose. Whether the tensile bond strength on irradiated dentin depends on the particular application mode (etch-and-rinse vs. self-etch) of the universal adhesives remains to be investigated.

Evaluation of the Polymer Modified Tack Coat on Aged Concrete Pavement: An Experimental Study on Adhesion Properties

This study addresses the challenges of overlaying old concrete pavement with asphalt by introducing a new trackless tack coat material containing polymer. The aim is to enhance the durability of asphalt concrete overlay pavement on old cement concrete pavement. It contributes to the development of improved construction techniques for pavement rehabilitation and highlights the need for reliable adhesion performance evaluation based on different spray amounts and surface conditions. Additionally, to evaluate the effect of the adhesion performance based on the spraying amount, a tensile adhesion test was conducted by applying spray amounts of 0.30, 0.45, and 0.60 l/m2 on different surface conditions. The basic and adhesion performances of the polymer-modified tack coat material are evaluated through direct tensile and shear bond strength tests. The test outcomes demonstrated that the newly developed polymer-modified tack coat material had considerably greater adhesion strength compared to the traditional rapid-setting products. Its adhesive strength was 1.68 times higher on concrete and 1.78 times higher on asphalt. The new trackless tack coat material exhibited an adhesion performance of 1.05 MPa in direct tensile strength at 0.45 l/m2, which was 1.21 times higher than the rapid-setting tack coat. Results also confirmed that the new tack coat material exhibits values 1.90 times greater than the conventional rapid-setting tack coat material in shear bond strength, respectively. By simulating the process of separation and re-adhesion of pavement layers caused, the new tack coat material shows a tensile adhesion strength of 63% of the original state, which is advantageous for securing the durability of the pavement. Overall, the newly developed polymer-modified trackless tack coat has been shown to effectively enhance the adhesion performance between pavement layers without process delay, highlighting the potential of the new tack coat material to enhance the durability of asphalt concrete overlay pavement on old cement concrete pavement.

Assessment of Cementitious Ceramic Tile Adhesives in the Light of Repeatability and Reproducibility of the Tensile Adhesion Strength Measurements.

The paper presents the results of tensile adhesion strength measurements of ceramic tile adhesive (CTA) stored in various conditions performed by ten operators in one laboratory using the same equipment and auxiliary materials. The obtained results allowed the authors to estimate the repeatability and reproducibility of the tensile adhesion strength measurement method using the methodology following ISO 5725-2:1994+AC1:2002. Standard deviations of repeatability ranging from 0.09 to 0.15 for the general means value in the range of 0.89-1.76 MPa and standard deviations of reproducibility ranging from 0.14 to 0.21 for the same general means content indicate that the accuracy of tensile adhesion strength measurement method is not high enough. From the group of ten operators, five perform tensile adhesion strength measurements daily, the remaining five perform other measures, and the results obtained by professionals and non-professionals showed no significant differences. In light of the obtained results, compliance assessment with this method with the criteria set out in the harmonized standard EN 12004:2007+A1:2012 carried out by different operators may be divergent, and there is a significant risk of incorrect assessments. This risk is additionally increasing in the case of the evaluation conducted by market surveillance authorities, which use the simple acceptance rule that does not consider measurement variability.

Characterization and Simulation of Nanoscale Catastrophic Failure of Metal/Ceramic Interfaces.

The catastrophic failure of metal/ceramic interfaces is a complex process involving the energy transfer between accumulated elastic strain energy and many types of energy dissipation. To quantify the contribution of bulk and interface cohesive energy to the interface cleavage fracture without global plastic deformation, we characterized the quasi-static fracture process of both coherent and semi-coherent fcc-metal/MgO(001) interface systems using a spring series model and molecular static simulations. Our results show that the theoretical catastrophe point and spring-back length by the spring series model are basically consistent with the simulation results of the coherent interface systems. For defect interfaces with misfit dislocations, atomistic simulations revealed an obvious interface weakening effect in terms of reduced tensile strength and work of adhesion. As the model thickness increases, the tensile failure behaviors show significant scale effects-thick models tend to catastrophic failure with abrupt stress drop and obvious spring-back phenomenon. This work provides insight into the origin of catastrophic failure at metal/ceramic interfaces, which highlights a pathway by combining the material and structure design to improve the reliability of layered metal-ceramic composites.

Alginate/polyacrylamide host-guest supramolecular hydrogels with enhanced adhesion

Although injectable hydrogels with minimally invasive delivery have garnered significant interest, their potential applications have been restricted by a singular property. In this study, a supramolecular hydrogel system with improved adhesion was constructed through host-guest interactions between alginate and polyacrylamide. The maximum tensile adhesion strength between the β-cyclodextrin and dopamine-grafted alginate/adamantane-grafted polyacrylamide (Alg-βCD-DA/PAAm-Ad, namely AβCDPA) hydrogels and pigskin reached 19.2 kPa, which was 76 % stronger than the non-catechol-based control hydrogel (β-cyclodextrin-grafted alginate/adamantane-grafted polyacrylamide, Alg-βCD/PAAm-Ad). Moreover, the hydrogels demonstrated excellent self-healing, shear-thinning, and injectable properties. The required pressure to extrude the AβCDPA2 hydrogel from a 16G needle at a rate of 2.0 mL/min was 67.4 N. As the polymer concentration and adamantane substitution degree increased, the hydrogels exhibited higher modulus, stronger network structure, and lower swelling ratio and degradation rate. Encapsulating and culturing cells within these hydrogels demonstrated good cytocompatibility. Therefore, this hydrogel can serve as a viscosity extender or bioadhesive, and as a carrier material to deliver encapsulated therapeutic substances into the body through minimally invasive injection methods.

Multi-Objective Optimization of Epoxy Resin Adhesive for Pavement Toughened by Self-Made Toughening Agent.

Epoxy resin adhesive for pavement is often insufficient in flexibility and toughness. Therefore, a new type of toughening agent was prepared to overcome this shortcoming. To achieve the best toughening effect of a self-made toughening agent on an epoxy resin adhesive, its ratio to the epoxy resin needs to be optimally selected. A curing agent, a toughening agent, and an accelerator dosage were chosen as independent variables. The epoxy resin's adhesive tensile strength, elongation at break, flexural strength, and flexural deflection were used as response values to establish a single-objective prediction model of epoxy resin mechanical property indexes. Response surface methodology (RSM) was used to determine the single-objective optimal ratio and analyze the effect of factor interaction on epoxy resin adhesive's performance indexes. Based on principal component analysis (PCA), multi-objective optimization was performed using gray relational analysis (GRA) to construct a second-order regression prediction model between the ratio and gray relational grade (GRG) to determine the optimal ratio and to validate it. The results showed that the multi-objective optimization using response surface methodology and gray relational analysis (RSM-GRA) was more effective than the single-objective optimization model. The optimal ratio of epoxy resin adhesive was 100 parts of epoxy resin, 160.7 parts curing agent, 16.1 parts toughening agent, and 3.0 parts accelerator. The measured tensile strength was 10.75 MPa, elongation at break was 23.54%, the bending strength was 6.16 MPa, and the bending deflection was 7.15 mm. RSM-GRA has excellent accuracy for epoxy resin adhesive ratio optimization and can provide a reference for the epoxy resin system ratio optimization design of complex components.