Adhesion Length Research Articles

ANN prediction of mode I fracture energy in epoxy adhesive joints: Adherend, adhesive, and strain rate effects

In this investigation, the mode I fracture behavior of an epoxy adhesive joint has been investigated to probe the combined effects of adherend Young's modulus and thickness, strain rate, and adhesive length. Experimental fracture testing was conducted on double-cantilever beam (DCB) specimens under three various strain rate thresholds, namely, quasi-static (0.0005 s−1), low (0.015 s−1), and intermediate (0.5 s−1). The specimens were constructed with varying adherend materials (i.e., copper, aluminum), thickness (12–20 mm), and adhesive lengths (25–75 mm). The fracture load was measured in each experiment, and the critical strain energy release rate, JCi, was calculated via a finite element analysis (FEA) in each case. Results with a 95 % confidence interval showed adherend thickness had a negligible effect within the investigated range (p-value = 0.462). JCi was significantly impacted by adhesive length (p-value = 0.009) and two other investigated parameters (p-values = 0.000). The development of artificial neural networks (ANNs) with Levenberg-Marquardt (LM) led to the prediction of JCi based on the examined parameters. With a mean absolute percentage error (MAPE) of 8.9 % and a mean squared error (MSE) of 683 J2/m4 on unseen test data, the ANN model built in this study was able to predict the JCi in epoxy adhesive joints, indicating its potential to produce an accurate prediction for JCi in epoxy adhesive joints. This work offers insights for precise fracture behavior prediction under mode I stress conditions as well as some helpful information that can be utilized to optimize adhesive joint design.

OPTICAL COHERENCE TOMOGRAPHY FEATURES ASSOCIATED WITH VITREOMACULAR TRACTION RELEASE AND MACULAR HOLE SIZE PROGRESSION FOLLOWING TREATMENT WITH OCRIPLASMIN.

To evaluate OCT features for vitreomacular traction (VMT) release and change in macular hole (MH) size after treatment with ocriplasmin. Patients who had undergone treatment with ocriplasmin for VMT with or without MH ≤400 µm were included. The main outcomes were VMT release and changes in minimum linear diameter MH size at 4 weeks in MHs that persisted. OCT features evaluated were central retinal thickness, vitreomacular adhesion length, posterior vitreous cortex (PVC) insertion angles 500 µm from the insertion points, and minimum linear diameter size. Sixty patients were included: 37 had isolated VMT and 23 VMT with a MH. Four weeks after ocriplasmin injection, the overall VMT release rate was 66.7% (40/60); 64.9% (24/37) in eyes with isolated VMT and 69.6% (16/23) in eyes with MH. VMT release was associated with younger age (P = 0.02). Macular hole closure was achieved in 26.1% (6/23) and was associated with a smaller ratio of the temporal to the nasal PVC angle (P < 0.01). Of the 17 persistent MHs, 76.5% (13/17) increased in minimum linear diameter size from baseline 186 (±78) to 358 (±133) µm (P < 0.001). Progression in minimum linear diameter size showed a negative linear association with the size of the nasal PVC angle (R2 = 0.39, P = 0.002) and a positive linear association with the ratio of the temporal to nasal PVC angle (R2 = 0.39, P = 0.002). In patients with VMT-associated MHs, the risk of MH enlargement following ocriplasmin is negatively correlated with the nasal PVC angle size and is increased if the ratio of the temporal to nasal angle is >1.

Programmable adhesion through triangular and hierarchical cuts in metamaterial adhesives.

Metamaterial design approaches, which integrate structural elements into material systems, enable the control of uncommon behaviours by decoupling local and global properties. Leveraging this conceptual framework, metamaterial adhesives incorporate nonlinear cut architectures into adhesive films to achieve unique combinations of adhesion capacity, release, and spatial tunability by controlling how cracks propagate forward and in reverse directions during separation. Here, metamaterial adhesive designs are explored with triangular cut features while integrating hierarchical and secondary cut patterns among primary nonlinear cuts. Both cut geometry and secondary cut features tune adhesive force capacity and energy of separation. Importantly, the size and spacing of cut features must be designed around a critical length scale. When secondary cut features are greater than a critical length, cracks can be steered in multiple directions, going both forward and backwards within a primary attachment element. This control over crack dynamics enhances the work of separation by a factor of 1.5, while maintaining the peel force relative to a primary cut. If hierarchical cut features are too small or too compliant, they interact and do not distinctly modify crack behaviour. This work highlights the importance of adhesive length scales and stiffness for crack control and attachment characteristics in adhesive films.This article is part of the theme issue 'Origami/Kirigami-inspired structures: from fundamentals to applications'.

Regimes in the axisymmetric stiction of thin elastic plates

This work considers the adhesion of a thin, prestressed elastic plate to the bottom of a microcavity – a scenario that can be found frequently in thin-film devices from pressure sensors to microfluidics. This adhesion phenomenon is also referred to as stiction in the field of nano/microelectromechanical systems (N/MEMS); the geometry we consider is axisymmetric (thereby we term this problem axisymmetric stiction). Motivated by the extreme thinness of increasingly exploited nanofilms such as 2D materials in functional devices, various limiting regimes of the axisymmetric stiction problem that arise due to the interplay of the bending, stretching, and pretension effects are discussed. Specifically, key dimensionless physical parameters in this problem are discussed and the range of these parameters for the classification of different regimes is outlined. This classification allows for analytical/asymptotic solutions for the critical adhesion conditions and the adhesion length in different regimes, many of which are not yet available in the literature. These analytical results are verified numerically and also compared with experiments based on 3-500 nm thick 2D materials. As such, this work provides a complete overview of the physically relevant regimes associated with axisymmetric stiction, establishing a regime diagram that can be directed used for the evaluation of the structural reliability of rapidly emerging thin plate devices.

Preoperative Structural Risk Factors for Glaucoma After Penetrating Keratoplasty for Congenital Corneal Opacity: An Observational Study.

Post-keratoplasty glaucoma (PKG) is a major complication following penetrating keratoplasty (PKP) for congenital corneal opacity (CCO). This study aims to assess the preoperative structural risk factors for PKG following PKP for CCO using ultrasound biomicroscopy (UBM). Pediatric patients with CCO who underwent preoperative UBM and primary PKP were enrolled. Patients with anterior segment operation history or witha follow-up duration less than 12months were excluded. The structural features of the anterior segment including central corneal thickness, anterior chamber depth, angle closure range (ACR), anterior synechia range, maximum iridocorneal adhesion length, abnormal iridocorneal synechia, and lens anomalies were identified on UBM images. The medical histories were reviewed to identify clinical features. The incidence of PKG was assessed to determine significant structural and clinical risk factors. Fifty-one eyes of 51 pediatric patients with CCO were included. The median age at surgery was 8.0months, and the mean follow-up duration was 33 ± 9months. Eleven (21.6%) eyes developed PKG. The main structural risk factors were abnormal iridocorneal synechia (P = 0.015), lens anomaly (P = 0.001), and larger ACR (P = 0.045). However, a larger range of normal anterior synechia without involvement of the angle was not a significant risk factor. Preoperative glaucoma (P < 0.001) and higher intraocular pressure (P = 0.015) were clinical risk factors. A shallow anterior chamber was a unique risk factor for sclerocornea (P = 0.019). Detailed preoperative examination of iridocorneal synechia, lens, and angle closure using UBM is critical for PKG risk assessment, surgical prognosis evaluation, and postoperative management in patients with CCO.

Experimental and Numerical Investigation of Impact Behaviour of Anchored CFRP-to-Concrete Bonding Interface

In the last 20 years, Carbon Fiber Reinforced Polymers (CFRP) have become a common alternative to strengthening and retrofitting. The performance of the strengthened specimens is closely related to the bond slip between the CFRP strips and the adhesion surface. Therefore, researchers have begun to concentrate on the various anchoring methods to delay the debonding of the CFRP from the surface of strengthened specimens. When the literature review of the adhesion behavior between the anchored CFRP strips and the concrete surface is examined, it has been shown that the investigations are mostly done under the effect of static or reversible cyclic loads. In the literature review, there is not any research related to the adhesion behavior between anchored CFRP strips and the concrete surface under the effect of sudden dynamic impulsive impact loading. Therefore, the variables examined in the experimental study are the anchor type used in the CFRP strips, CFRP strip adhesion length, and the number of anchors placed on the strip. As a result of the experiments, the acceleration-time, displacement–time curves of the beams, and the strain–time curves along the CFRP strips were interpreted. In addition, simulation models of the test specimens were created with ABAQUS software, and non-linear finite element analyzes were performed. Finally, by comparing numerical results with experimental ones, the effects of variables such as bond length, applied anchor types and numbers on the impact behavior of the beam and the strain distributions along the CFRP strips were interpreted.

Abstract Or111: Titin cleavage disrupts sarcomere-adhesion tensional homeostasis triggering cardiomyocyte arrhythmia in vitro

The cardiac tissue experiences several forms of mechanical stress, including contraction of cardiomyocytes and forces derived from the stiffness of extracellular matrix (ECM). Preserving homeostatic mechanical forces is crucial for a healthy heart, yet the mechanisms involved are not well-explored. Our study delves into cardiomyocyte responses following the sudden release of mechanical tension across titin, a giant sarcomere protein crucial for setting cardiomyocyte stiffness. Through the expression of virally transduced TEV protease (TEVp) in neonatal mouse cardiomyocytes (NMCMs), we induced the cleavage of mutant titin including the specific TEV protease recognition site (TEVs) within the mechanically active I-band region of the protein. Titin cleavage was validated by 1.8% polyacrylamide SDS-PAGE electrophoresis, revealing a primary band at ~2.2 MDa in TEV-positive NMCMs, corresponding to digested titin fragment A-M. This cleavage, confirmed at 2 days post-infection (dpi) with ~80% efficiency, reached 100% by 5 dpi. Consequently, the Young’s modulus of affected cardiomyocytes dropped by 50%, as determined by Atomic Force Spectroscopy. Sarcomere disarray increased over time, as evidenced by immunofluorescence, yet this effect did not induce cell death or proliferation. Cell viability was confirmed by the fact that affected cardiomyocytes are able to contract spontaneously, although titin cleavage resulted in reduced beating amplitude and induced arrhythmic behavior. Considering this arrhythmogenic situation, we tested cell-cell adhesion through dissociation assays, which revealed significantly reduced intercellular adhesion in affected cardiomyocytes. RNAseq confirmed involvement of pathways related to heart contraction, anchoring junctions, and cell junctions. Specifically, dysregulated genes associated with gap-junction and costamere complexes were observed at 5 dpi. Alterations of adhesion were further confirmed by reductions in connexin 43 and focal adhesion length in immunofluorescence experiments, which also showed mislocalization of important adhesive proteins. In conclusion, titin cleavage in neonatal cardiomyocytes leads to sarcomere disarray, perturbed cell-cell adhesion and arrhythmia. These findings highlight the importance of full mechanical integrity of the titin filament in living cardiomyocytes.

Investigation on activation performance of adhesive bonding connection between Fe-SMA and steel plates

Steel structures are extensively utilized in civil engineering because of their advantageous characteristics. However, cyclic loading can induce cracks in steel structures, resulting in a decline in mechanical properties and increased life cycle costs. In recent times, iron-based shape memory alloys (Fe-SMAs) have gained recognition as promising materials for structural reinforcement due to their distinct shape memory effect. The adhesive bonding connection between Fe-SMA and steel offers an efficient solution for reinforcing steel structures, enabling uniform stress transfer without introducing defects. This study investigates the influence of the geometric dimensions of Fe-SMA plates and the structural adhesive on the stress of steel plates through activation tests and finite element simulations. A multiple regression model has been proposed to describe the relationship between the size of Fe-SMA plates, structural adhesive, and the stress of steel plates. In addition, the temperature of the adhesive during activation is determined through activation tests. According to test results, a temperature distribution model for the adhesive has been developed, allowing for an accurate theoretical calculation of the adhesive softening length. The adhesive softening significantly impacts the stress distribution of the steel plate, making this model considerably valuable. This study provides valuable experimental data and a theoretical basis for the practical implementation of Fe-SMA in metal structural reinforcement.

On the Adhesive Interaction Between Metals in Atomistic Simulations of Friction and Wear

Atomistic simulations are performed to assess how the main characteristics of a pairwise interatomic potential function can affect the occurrence of wear. A Morse-like potential is tailored in its attractive part such as to vary independently the cut-off radius and the maximum value of the attractive (adhesive) force. An ideal numerical experiment is then performed where the interaction between a metal crystal and a probe changes, while their material properties are not affected, to isolate the behavior of the interface. Force functions with larger adhesive force can loosely be interpreted as describing dry contacts while those with smaller adhesive force can be interpreted as describing lubricated contacts. Results demonstrate that the occurrence of wear is strongly dependent on the shape of the interatomic force field, and more specifically on the combination of maximum adhesive force and effective length of the interatomic attraction. Wear can initiate also at small adhesive energy, provided that the maximum adhesive force between atoms is large. When the surface of the crystal is taken to be rough instead of flat, the effect of the interatomic potential function on friction and wear becomes smaller, as the atoms belonging to the roughness are weakly bound to the rest of the crystal and are easily dislodged with any of the force functions we used.

Crocin elicits potent anti-inflammatory and fibrinolytic properties post tendon injury, A new molecule for adhesion therapy

BackgroundPost-surgical tendon adhesion formation is a frequent clinical complication with limited treatment options. The aim of this study is to investigate safety and efficacy of orally administration of crocin in attenuating post-operative tendon-sheath adhesion bands in an Achilles tendon rat model. MethodsStructural, mechanical, histological, and biochemical properties of Achilles tendons were analyzed in the presence and absence of crocin. Inflammation and total fibrosis of tendon tissues were graded between groups using macroscopic and histological scoring methods. ResultsCrocin significantly alleviated the severity, length, and density of Achilles tendon adhesions. Moreover, the recruitment of inflammatory cells and inflammation were significantly decreased in post-operative tissue samples of the crocin-treated group, as quantified with Moran scoring system. Histological results showed that crocin elicited a potent anti-fibrotic effect on tendon tissue samples as visualized by decreasing quantity, quality, grading of fibers, and collagen deposition at the site of surgery when scored either by Tang or Ishiyama grading systems. The H&E staining showed no histo-pathological changes or damage to heart, kidney, and liver tissues of treated rats. ConclusionOur results showed that crocin is a safe effective therapeutic candidate with potent anti-inflammatory and anti-fibrotic properties for adhesion band therapy post tendon surgery.

Adhesion characteristics of carbon nanotube gecko tapes for micrometer-sized particles

ABSTRACT A detailed understanding of the adhesive properties of a carbon nanotube (CNT)-based gecko tape with respect to microscale particles is necessary for its practical application as a supporting medium for specific solid materials. We obtained the force curves of vertically aligned CNTs (VACNTs) for individual microparticles of various diameters using atomic force microscopy and evaluated their adhesion force and adhesion length. The measured adhesive force followed the apparent contact area with increasing embedding depth and was size-dependent at scales of several tens of micrometers. The adhesive forces measured for a 20 µm-diameter bead was significantly higher than those for larger particles, which may be related to inclination of the adherent surface against the VACNT tape surface. The adhesion length depended on the type of the CNTs comprising the VACNT, rather than on the bead size. The evaluation of VACNTs with different morphologies suggested that the flexibility of the individual CNTs and the density of the CNT – CNT interconnections in the VACNTs were important factors for obtaining the true contact area to realize better adhesion of micrometer-sized particles.

Rab35 Is Required for Embryonic Development and Kidney and Ureter Homeostasis through Regulation of Epithelial Cell Junctions.

Rab35 is a member of a GTPase family of endocytic trafficking proteins. Studies in cell lines have indicated that Rab35 participates in cell adhesion, polarity, cytokinesis, and primary cilia length and composition. Additionally, sea urchin Rab35 regulates actin organization and is required for gastrulation. In mice, loss of Rab35 in the CNS disrupts hippocampal development and neuronal organization. Outside of the CNS, the functions of mammalian Rab35 in vivo are unknown. We generated and analyzed the consequences of both congenital and conditional null Rab35 mutations in mice. Using a LacZ reporter allele, we assessed Rab35 expression during development and postnatally. We assessed Rab35 loss in the kidney and ureter using histology, immunofluorescence microscopy, and western blotting. Congenital Rab35 loss of function caused embryonic lethality: homozygous mutants arrested at E7.5 with cardiac edema. Conditional loss of Rab35, either during gestation or postnatally, caused hydronephrosis. The kidney and ureter phenotype were associated with disrupted actin cytoskeletal architecture, altered Arf6 epithelial polarity, reduced adherens junctions, loss of tight junction formation, defects in EGFR expression and localization, disrupted cell differentiation, and shortened primary cilia. Rab35 is essential for mammalian development and the maintenance of kidney and ureter architecture. Loss of Rab35 leads to non-obstructive hydronephrosis, making the Rab35 mutant mouse a novel mammalian model to study mechanisms underlying this disease.

Influence of calcium concentration on larval adhesion in a highly invasive fouling ascidian: From morphological changes to molecular mechanisms

Calcium ion (Ca2+) is involved in the protein-mediated larval adhesion of fouling ascidians, yet the effects of environmental Ca2+ on larval adhesion remain largely unexplored. Here, the larvae of fouling ascidian C. robusta were exposed to different concentrations of Ca2+. Exposures to low-concentration (0 mM and 5 mM) and high-concentration (20 mM and 40 mM) Ca2+ significantly decreased the adhesion rate of larvae, which was primarily attributed to the decreases in adhesive structure length and curvature. Changes in the expressions of genes encoding adhesion-, microvilli-, muscle contraction-, and collagen-related proteins provided a molecular-level explanation for adhesion rate reduction. Additionally, larvae likely prioritized their energy towards immunomodulation in response to Ca2+ stresses, ultimately leading to adhesion reduction. These findings advance our understanding of the influencing mechanisms of environmental Ca2+ on larval adhesion, which are expected to provide references for the development of precise antifouling strategies against ascidians and other fouling species.

Strain Measurement with Optic Fibers for Structural Health Monitoring of Woven Composites: Comparison with Strain Gauges and Digital Image Correlation Measurements.

In this work, the strains measured with optic fibers and recorded during tensile tests performed on carbon/epoxy composite specimens were compared to those recorded by strain gauges and by Digital Image Correlation (DIC). The work aims at investigating the sensitivity of embedded and glued optic sensors for structural health monitoring applications in comparison with strain gauges and the full field strain map of the DIC. Acrylate, polyimide optic fibers, and three strain gauge sizes are considered to compare the three techniques. Results show hard polyimide-coated sensors are more sensitive to the material pattern than soft acrylate-coated fibers, which also require extensive adhesion length. The work shows a comparable size of strain gauges and material meso-structure is also critical for properly assessing material properties. The Young's modulus computed with the three different techniques is used to define a strategy that supports the selection and the proper size of the adopted strain measuring system for structural health monitoring of composite materials.

Efficacy of Naldemedine on Intestinal Hypomotility and Adhesions in Rodent Models of Postoperative Ileus.

Postoperative ileus (POI) often decreases patients' QOL because of prolonged hospitalization and readmission. Alvimopan, a peripheral μ-opioid receptor antagonist, is currently the only therapeutic drug for POI. The aim of this study was to examine the efficacy of naldemedine (a peripheral μ-opioid receptor antagonist with a non-competitive pharmacological profile different from that of alvimopan) on postoperative intestinal hypomotility and adhesion in rodent models, and compare it with the effects of alvimopan. Oral administration of naldemedine (0.3 mg/kg) and alvimopan (3 mg/kg) significantly inhibited the decrease in intestinal motility induced by mechanical irritation in mice (p < 0.01, for both). Naldemedine (1 mg/kg) significantly shortened the adhesion length in chemical-induced postoperative adhesion model rats (p < 0.05). Alvimopan (3 mg/kg) also significantly reduced the adhesion ratio (p < 0.01). These findings suggest that naldemedine is effective for postoperative intestinal hypomotility and adhesions in rodents (i.e., as for alvimopan). Thus, naldemedine may be a useful option for the treatment of POI.

Inside vesicle adhesion between two vesicles in 2-D case

A theoretic model is proposed to study the adhesion behavior of a vesicle adhering inside another vesicle in 2-D case. The equilibrium shape equations and boundary conditions are investigated. With zero pressure, the integral case of the shape equations with dimensionless parameters is derived. When a soft vesicle adheres inside a rigid ring, the bifurcation between two phases is revealed, the critical adhesion condition and phase diagram are obtained. The finite element method (FEM) is used to study the deformation processes induced by the change of work of adhesion and bending rigidity. The relationships between the energy, adhesion length, cell volume, bending rigidity and work of adhesion are obtained.

The peeling behavior of a heterogeneous elastic film on a rigid substrate

Although the interfacial peeling behavior of a homogeneous film-substrate system is well understood, the peeling process of a heterogeneous elastic film bonded to a rigid substrate is still unclear. In the present paper, the peeling behavior of a heterogeneous film adhering on a rigid substrate under a vertical peeling force is investigated theoretically, in which the film’s heterogeneity is characterized by the change of bending stiffness along the length of the film. Based on the principle of minimum potential energy, the typical relationship between the peeling force and the peeling displacement during the whole peeling process is achieved. Different from the homogeneous film case, the peeling force can be regulated dramatically by the film’s heterogeneous bending stiffness during the peeling process. When the interfacial debonding front propagates from a compliant segment to a stiff segment, the peeling force is enhanced; while the peeling force is weakened as the interfacial debonding front goes from a stiff segment to a compliant one. The enhancement or weakening of the peeling force depends not only on the bending stiffness of each segment of the film but also on the bending stiffness ratio of neighboring segments, as well as the adhesion length of each segment and the interfacial adhesion properties. The mechanism underlying the heterogeneity-induced tunable peeling force is further elucidated by the change rate of elastic bending energy stored in the film and energy overcoming the interfacial interaction potential during the peeling process. The transfer and redistribution of the elastic bending energy are the main factors that induce the change of peeling force as the interfacial debonding front reaches the boundary of neighboring segments with different bending stiffness. The results of this paper can provide a new strategy for designing film-substrate systems with adjustable adhesion without changing the interfacial characteristics.

Low, medium, and high molecular weight hyaluronic acid effects on human dental pulp stem cells in vitro

Hyaluronic acid (HA), an extracellular biopolymer found throughout the human body, holds promise as a biocompatible and biodegradable scaffold material. High molecular weight (HMW) HA degrades, generating low molecular weight (LMW) fragments with distinct properties. These fragments can influence the behaviour of cells, including human dental pulp stem cells (hDPSCs) incorporated into HA-containing hydrogels or scaffolds. Therefore, a comprehensive examination of the impact of a range of HA molecular weights on hDPSCs is essential before designing HA-based scaffolds for these cells. hDPSC lines were cultured with LMW HA (800 Da, 1600 Da, 15 kDa), medium molecular weight HA (237 kDa), or HMW HA (1500 kDa) over six passages. The various molecular weights had negligible effects on hDPSCs viability, morphology, adhesion, or relative telomere length. Furthermore, the expression of key surface stemness markers (CD29, CD44, CD73, CD90) remained unaltered. HA did not induce osteogenic, chondrogenic, or adipogenic differentiation. Moreover, the potential for chondrogenic and osteogenic differentiation was not adversely affected by LMW or HMW HA. Various molecular weights of HA seem safe, biocompatible and therefore suitable components for hDPSCs-containing scaffolds. These findings affirm that the hDPCSs will not be negatively affected by HA fragments resulting from scaffold degradation.

The effect of split injection on fuel adhesion characteristics under static flow and cross-flow field conditions

The flat-wall wetting phenomenon is inevitable because of the smaller cylinder volume and higher injection pressure inside direct-injection spark ignition (DISI) engines. The fuel adhesion phenomenon after wall impingement negatively affects the fuel spray mixture formation, the fuel consumption, and the pollutant emissions. In this study, the effects of different fuel injection strategies on the wall-impingement behavior were compared under static flow and cross-flow field conditions. The refractive index matching (RIM) method and high-speed video (HSV) camera were adopted to measure the propagation of fuel adhesion and the spray structure of the vertical plane, respectively. Meanwhile, a dimensionless parameter named “deformation coefficient Id,” which is defined as the fuel adhesion length divided by the width, is proposed to evaluate the degree of distortion of the fuel adhesion. Therefore, when Id approaches 1, the fuel adhesion shape approaches a circle. The results show that the cross-flow promotes the diffusion of the fuel spray, which leads to an increase in the fuel adhesion area. The fuel adhesion shape is similar to that of a slender strip under cross-flow field conditions, but almost maintains a circle under static flow field conditions. The cross-flow decreased the average fuel adhesion thickness. Meanwhile, the cross-flow also promotes the evaporation of the adhered fuel on a flat-wall, which leads to a reduction in the fuel adhesion area and mass with time. Additionally, it was found that triple injection can decrease the fuel adhesion thickness, area, and mass ratio under cross-flow field conditions. To achieve carbon neutrality, optimizing fuel injection strategies to reduce emissions is one of the primary purposes of this study.

Topological optimization BI-adhesive double lap adhesive joint. One-dimension model

The aim of the article is to construct a solution to the problem of topological optimization of a symmetric two-shear and bi-adhesive joint. The one-dimensional mathematical model of the stress state of a symmetrical double-shear adhesive joint with a variable thickness of the outer substrate along the lap length is represented in the article. The proposed model is a generalization of the classical Goland-Reissner model. The proposed mathematical model is used to solve the problem of topological optimization of the outer substrate shape as well as to obtain the optimal length of the sections for the rigid and compliant adhesives. The expansion of the outer substrate thickness dependence along the adhesive joint length into a Fourier series in cosines was used to describe the shape of the outer substrate. The desired values in the optimization problem are the lengths of the adhesive joint sections with the compliant and rigid adhesives as well as the Fourier coefficients. The objective function is the cross-sectional area of the outer substrate. Restrictions are imposed on the maximum stresses in the adhesive layer and in the outer substrate. A genetic algorithm was used to solve the optimization problem. The direct problem of determining the stress state of the adhesive joint at specified parameters was solved using the finite difference method. The model problem is solved and the results of the stress state calculation are compared with the results of finite element modeling.