Monitoring method for interfacial bond-slip performance and its degradation evolution in composite components

Abstract

The present invention discloses a method for monitoring the interfacial bond-slip performance and degradation evolution thereof in a composite component, comprising the following steps: performing a degreasing and cleaning pretreatment on a profile with relatively high stiffness in the composite component to be tested to obtain the pretreated profile; arranging a distributed optical fiber sensor based on Rayleigh scattering on the surface of the pretreated profile along the direction of the measured bonding force; bonding the profile on which the distributed optical fiber sensor is arranged to a substrate to be tested by means of an adhesive to prepare a composite component; performing a uniaxial tensile test on the composite component, recording the distribution and evolution of the strain of the steel bars during the test by means of the distributed optical fiber sensor, and obtaining the distribution and evolution of the bond-slip relationship, thereby enabling the study of the local bond-slip relationship and improving the applicability and accuracy of the bond-slip model; and applying a working condition to the composite structure before uniaxial stretching to degrade the structure, thereby enabling the evaluation of the influence of the degradation on the bonding performance of the composite structure.

Description

Technical Field

[0001] The present invention relates to the technical field of bond-slip constitutive measurement, in particular to a method for monitoring interface bond-slip performance and degradation evolution thereof in a composite component. Background Art

[0002] Bond is an important mechanical property between two materials. It is the basis for the two materials / two components in a composite member to work together, affecting the composite properties of the materials and the stability of the structure. Taking reinforced concrete structures as an example, the interaction between steel and concrete determines the mechanical properties of reinforced concrete structures, including strength, deformation, durability, and crack control. It plays a decisive role in the structural performance of reinforced concrete structures under the limit state of normal use and the ultimate state of bearing capacity. In finite element analysis, the bond-slip relationship directly affects the mechanical performance and failure mode of the structure, and is crucial for accurately predicting and evaluating the structural performance of reinforced concrete. Therefore, the study of the bond-slip relationship between the interfaces of composite components has important research significance and engineering application value.

[0003] Traditionally, the bond-slip relationship between reinforced concrete is extracted through pull-out tests, using the average bond stress obtained from the test to characterize the local bond strength of reinforced concrete. However, the bond-slip relationship between reinforced concrete varies along the length and is affected by factors such as the local mechanical properties of the component, the local stress conditions, and historical loads. Therefore, the bond-slip relationship measured by the pull-out test cannot be well applied to complex structures. Although researchers have attempted to approximate the distribution of bond strength along the length by attaching strain gauges externally or internally, the presence of strain gauges affects the bond performance between reinforced concrete and can only provide limited and discrete strain information. Despite the significant human and material resources involved, our understanding of the bond-slip behavior of reinforced concrete remains very limited. In addition, strain gauges are not corrosion-resistant and easily damaged, making them unsuitable for monitoring the bond-slip relationship between reinforced concrete under complex working conditions. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for monitoring the interfacial bond-slip performance and its degradation evolution in composite components, which can study the local bond-slip relationship and improve the applicability and accuracy of the bond-slip model.

[0005] The technical solution of the present invention is:

[0006] A method for monitoring the interfacial bond-slip performance in a composite component comprises the following steps:

[0007] S1. Performing a degreasing and cleaning pretreatment on the profile with relatively high stiffness in the composite component to be tested to obtain the pretreated profile;

[0008] S2, arranging the distributed optical fiber sensor on the surface of the pretreated profile along the direction of the measured bonding force;

[0009] S3, bonding the profile on which the distributed optical fiber sensor is arranged to the substrate to be measured by adhesive to prepare a combined component;

[0010] S4. Performing a uniaxial tensile test on the composite component, recording the distribution and evolution of the steel bar strain during the test using a distributed optical fiber sensor, and obtaining the distribution and evolution of the bond-slip relationship.

[0011] Furthermore, the profiles described in S1 include but are not limited to plain round steel bars, ribbed steel bars, deformed steel bars and FRP bars.

[0012] Furthermore, the composite component described in S3 is not limited to a specific material, and any one of reinforced concrete structure, steel tube concrete structure, FRP reinforced concrete structure, CFRP reinforced concrete structure or CFRP steel structure can be selected according to the test purpose and test requirements.

[0013] Furthermore, the adhesive in S3 is cyanoacrylate adhesive, which is quick-drying and has great rigidity, thereby ensuring that the distributed optical fiber sensor and the measured profile deform in coordination.

[0014] Furthermore, in S2, the distributed optical fiber sensor and the pretreated profile are deformed in coordination, providing protection for the distributed optical fiber sensor. The protective measures can be arranged in two ways: To improve the survival rate of the distributed optical fiber sensor, a fiber optic groove can be provided on the profile along the direction of the measured bonding force, and the distributed optical fiber sensor can be placed along the fiber optic groove; or a silicone protective layer can be provided over the distributed optical fiber sensor to protect the optical fiber sensor.

[0015] Furthermore, the bonding method between the profile and the substrate to be tested is determined according to the test purpose and test requirements, including but not limited to pouring bonding between the profile and concrete, and gluing between the FRP cloth and the profile.

[0016] Furthermore, the shapes of the profile and the base are determined according to the test purpose and test requirements, and any one of reinforced prismatic components, reinforced cylindrical components, concrete components reinforced with FRP plates, or concrete components reinforced with FRP bars is selected.

[0017] Furthermore, the experimental loading method of the uniaxial tensile test described in S4 is designed according to the test purpose and test requirements, including but not limited to monotonic loading, cyclic loading considering fatigue factors, and loading-unloading-reloading loading method considering historical load factors. Compared with the bond-slip relationship obtained by the pull-out test, the stress conditions of this method are more consistent with the stress conditions in actual engineering applications, and the obtained bond-slip relationship is more realistic and accurate.

[0018] Furthermore, a method for monitoring the interfacial bond-slip performance in a composite component and a method for monitoring the degradation evolution of the interfacial bond-slip performance in a composite component also includes the following steps: before performing a uniaxial tensile test on the composite component, applying working conditions to the composite component to degrade the structure, obtaining the bond-slip distribution and evolution of the composite component in the degraded state, and evaluating the impact of the degradation on the bond performance of the composite structure. The working conditions applied to the composite component refer to working conditions that can affect the mechanical properties and performance of the composite structure to be tested, including but not limited to FPR ultraviolet aging, FRP wet-heat aging, and steel bar corrosion damage. The purpose of applying working conditions is to explore and obtain the bond-slip relationship of the component under a certain working condition, and to evaluate the impact of the working condition on the bond-slip relationship.

[0019] Furthermore, a method for monitoring the interfacial bond-slip performance in composite components can be applied to extract the bond-slip relationship of adhesively bonded components.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention monitors the bond-slip relationship of a composite structure through a uniaxial tensile test. Compared to the bond-slip relationship obtained through a pull-out test, the stress conditions of this method are more consistent with the stress conditions in actual engineering applications, and the resulting bond-slip relationship is more realistic and accurate. Furthermore, the method has the ability to analyze the evolution of bond-slip during load-bearing, thereby deepening the understanding of the bond-slip relationship of composite structures and contributing to the development and advancement of bond-slip monitoring technology. Furthermore, the distributed optical fiber sensor is small in size, lightweight, and non-invasive, and does not affect the bonding performance between materials. The measured data results are more realistic and reliable. By recording the distribution and evolution of steel bar strain during the test using distributed optical fiber, the distribution and evolution of bond force and slip values ​​along the stress direction are obtained. Compared to the discrete data measured by strain gauges, the method has the ability to study local bond-slip relationships and can improve the applicability and accuracy of the bond-slip model.

[0022] 2. The bond-slip monitoring technology provided by the present invention can add multiple working conditions to composite components to obtain the bond-slip relationship between degraded composite structures under specific working conditions (such as cyclic loading and UV aging of FRP structures), providing support for the study of the bond-slip behavior of composite structures under complex working conditions.

[0023] 3. The bond-slip monitoring technology provided by the present invention can also be used to extract and monitor the bond-slip relationship of bonded components, which can meet the application requirements of various bond-slip relationship models, provide a multivariate and accurate bond-slip model for the bond-slip model of finite element analysis and numerical analysis, and improve the reliability and accuracy of finite element analysis and numerical analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the direct arrangement of the distributed optical fiber sensor of the present invention.

[0025] Figure 2 for Figure 1 Schematic diagram of the structure in cross section.

[0026] Figure 3 This is a schematic diagram of the distributed optical fiber sensors arranged in the optical fiber grooves processed according to the present invention.

[0027] Figure 4 for Figure 3 Schematic diagram of the structure in cross section.

[0028] Figure 5 This is a schematic diagram of using silicone to protect distributed optical fiber sensors in the present invention.

[0029] Figure 6 for Figure 5 Schematic diagram of the structure in cross section.

[0030] Figure 7 Schematic diagram of a typical test device for bond slip of reinforced concrete tie rod structure according to the present invention.

[0031] Figure 8 Schematic diagram of the distribution and evolution of the bond force of reinforced concrete structure extracted by the present invention.

[0032] Figure 9 Schematic diagram of the bond-slip test of the reinforced concrete tie rod structure under cyclic load and corrosion according to the present invention.

[0033] Figure 10 Schematic diagram of strain distribution of reinforced concrete tie rod structures with different corrosion degrees monitored by the present invention.

[0034] Figure 11 for Figure 10 Schematic diagram of the bond force distribution of reinforced concrete tie rod structures with different corrosion degrees extracted from the strain distribution.

[0035] Among them, 1. distributed fiber optic sensor, 2. steel bar, 3. FRP, 4. silicone, 5. concrete. DETAILED DESCRIPTION

[0036] The following combination Figures 1 to 11, the specific embodiments of the present invention are described in detail. In the description of the present invention, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings and are only used to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific direction, be constructed or operate in a specific direction, and therefore should not be understood as limiting the present invention.

[0037] The terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include one or more of such features; in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0038] Example

[0039] A method for monitoring the interfacial bond-slip performance in a composite component is used to monitor the bond-slip relationship between a profile and a substrate to be tested, comprising the following steps:

[0040] S1. Degreasing and cleaning the relatively high-rigidity profiles in the composite component to be tested, i.e., the main load-bearing materials, to obtain pretreated profiles. The profiles include but are not limited to plain round steel bars, ribbed steel bars, deformed steel bars, FRP bars, and other composite materials with a certain degree of rigidity;

[0041] S2. Distributed optical fiber sensors are arranged on the surface of the pre-treated profile along the direction of the measured bonding force. The distributed optical fiber sensors and the pre-treated profile are deformed in coordination. The distributed optical fiber sensors used in this embodiment are distributed optical fiber sensors based on Rayleigh scattering, which have higher resolution and accuracy. It is worth noting that different bonding techniques can be used to arrange the optical fibers according to the type of optical fibers used and the test requirements. For example, Figure 1 and Figure 2 As shown in Figure 2, the arrangement of the optical fiber sensor is as follows: a 0.9 mm diameter sheathed optical fiber is directly attached to the ribbed steel bar along the longitudinal rib of the steel bar; Figure 3-Figure 6 The arrangement shown in the figure imposes certain protection measures on the distributed optical fiber sensor to improve the survival rate of the distributed optical fiber sensor. Figure 3 and Figure 4 As shown in the figure, an optical fiber groove is opened on the profile along the direction of the measured bonding force, and the distributed optical fiber sensor is placed along the optical fiber groove, as shown in the figure. Figure 5 and Figure 6 As shown, a silicone protective layer is covered on the distributed optical fiber sensor to protect the optical fiber sensor.

[0042] S3. The profile with the distributed optical fiber sensor arranged is bonded to the substrate to be measured by an adhesive, such as concrete, to form a composite component. The profile extends from both ends of the composite component to serve as a tensile clamping section. The specific structure is shown in the attached figure. Figure 7 As shown, specifically, the bonding between the profile and the substrate to be tested, and the bonding method are determined according to the test purpose and test requirements, including but not limited to the pouring bonding between the profile and concrete, and the bonding between the FRP cloth and the profile;

[0043] S4. Perform a uniaxial tensile test on the composite component, and record the distribution and evolution of the steel bar strain during the test using a distributed optical fiber sensor to obtain the distribution and evolution of the bond-slip relationship. By recording the distribution and evolution of the steel bar strain and its corresponding load during the test using a distributed optical fiber sensor and a tensile instrument, the distribution and changes of the bond strength and slip value of the composite component can be obtained, such as Figure 8 As shown in FIG, the loading method of the uniaxial tensile test is designed according to the test purpose and test requirements, including but not limited to monotonic loading, cyclic loading considering fatigue factors, and loading-unloading-reloading loading method considering historical load factors.

[0044] Specifically, the composite components in S3 are not limited to a specific material, and any one of reinforced concrete structure, steel tube concrete structure, FRP reinforced concrete structure, CFRP reinforced concrete structure, and CFRP steel structure can be selected according to the test purpose and test requirements.

[0045] In some embodiments, the adhesive in S3 is a cyanoacrylate adhesive, which is quick-drying and has relatively high rigidity, to ensure that the distributed optical fiber sensor and the measured profile deform in coordination.

[0046] The shapes of the profile and the base are determined according to the test purpose and test requirements, and any one of reinforced prismatic components, reinforced cylindrical components, concrete components reinforced with FRP plates, and concrete components reinforced with FRP bars can be selected.

[0047] Due to the influence of factors such as the environment, loads, and material aging, composite structures inevitably experience structural damage and functional degradation during their service life. This degradation can alter the bonding properties of composite structures, severely reducing their service life and endangering their safety. Currently, the assessment of the mechanical properties of composite structures in a degraded state is primarily based on monitoring data of local material properties and overall structural performance. Direct monitoring methods for the degradation of bond slip between interfaces within composite structures are lacking, limiting the precise assessment of the residual performance of composite structures in a degraded state. Consequently, methods for assessing the impact of degradation on the bonding properties of composite structures urgently need to be improved and developed.

[0048] Before the uniaxial tensile test of the composite component in S4 of this embodiment, the composite component is subjected to working conditions to degrade the structure, and the bond slip distribution and evolution of the composite component in the degraded state are obtained to evaluate the impact of degradation on the bonding performance of the composite structure. The working conditions applied to the composite component in S4 refer to working conditions that affect the mechanical properties and performance of the composite structure to be tested, including but not limited to FPR UV aging, FRP hygrothermal aging, and steel bar corrosion damage, for example Figure 9 The accelerated corrosion test of reinforced concrete shown in the figure applies the working corrosion environment to the composite components, and the results are as follows Figure 10 、 Figure 11 The stress distribution and evolution diagrams and the bond force distribution and evolution diagrams of different corroded components under the same load are shown.

[0049] The above-mentioned method for monitoring the interfacial bond-slip performance in composite components can also be applied to extract the bond-slip relationship of adhesive components.

[0050] The above disclosures are only several preferred specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the scope of protection of the present invention.

Claims

1. A method for monitoring the interfacial bond-slip performance in a composite component, for detecting the bond-slip relationship between a profile and a substrate to be tested, characterized in that: The following steps are involved: S1. Degreasing and cleaning the profiles in the assembly to be tested to obtain pretreated profiles; S2, arranging the distributed optical fiber sensor on the surface of the pretreated profile along the direction of the measured bonding force; S3, bonding the profile on which the distributed optical fiber sensor is arranged to the substrate to be measured by adhesive to prepare a combined component; S4. performing a uniaxial tensile test on the composite component, recording the distribution and evolution of the profile during the test using a distributed optical fiber sensor, and obtaining the distribution and evolution of the bond-slip relationship; In S2, the distributed optical fiber sensor and the pre-treated profile are deformed in coordination, and the arrangement of the distributed optical fiber sensor includes the following two methods: A fiber optic groove is provided on the profile along the direction of the measured bonding force, and a distributed fiber optic sensor is placed along the fiber optic groove; or, A silicone protective layer is covered on the distributed optical fiber sensor to protect the optical fiber sensor; The loading method of the uniaxial tensile test described in S4 is designed according to the test purpose and test requirements, including monotonic loading, cyclic loading considering fatigue factors, or loading-unloading-reloading loading method considering historical load factors; Before conducting a uniaxial tensile test on the composite component, working conditions are applied to the composite component to cause structural deterioration. The bond slip distribution and evolution of the composite component in the degraded state are obtained to evaluate the impact of degradation on the bonding performance of the composite structure. The applied working conditions include FRP ultraviolet aging, FRP wet-heat aging, or steel bar corrosion damage.

2. The method for monitoring the interfacial bond slip performance in a composite component according to claim 1, characterized in that: The composite member described in S3 is not limited to a specific material, and any one of reinforced concrete structure, steel tube concrete structure, FRP reinforced concrete structure or CFRP steel structure can be selected according to the test purpose and test requirements.

3. The method for monitoring the interfacial bond slip performance in a composite component according to claim 1, characterized in that: The adhesive in S3 is a cyanoacrylate adhesive.

4. The method for monitoring the interfacial bond slip performance in a composite component according to claim 1, characterized in that: The profiles described in S1 include plain round steel bars, deformed steel bars or FRP bars.

5. The method for monitoring the interfacial bond-slip performance in a composite component according to claim 1, characterized in that: The bonding method between the profile and the substrate to be tested is determined according to the test purpose and test requirements, including pouring bonding between the profile and concrete, and gluing between the FRP cloth and the profile.

6. The method for monitoring the interfacial bond slip performance in a composite component according to claim 1, characterized in that: The shapes of the profile and the base are selected from any one of a reinforced prism component, a reinforced cylindrical component, a concrete component reinforced with an FRP plate, or a concrete component reinforced with an FRP bar.

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