System and method for detecting mechanical property of micro area of composite material structure

Abstract

The invention provides a system and a method for detecting the mechanical property of a micro area of a composite material structure, and belongs to the technical field of material mechanical testing equipment. Comprising a fixing base and testing equipment, a clamping device is arranged in the fixing base and used for fixing a tiny test piece, force generated by the testing equipment is transmitted to the tiny test piece, a pressing disc is arranged in the testing equipment and controlled by a servo motor to move, and force is applied to the tiny test piece fixed in the clamping device; and an improved short beam shearing method is adopted for interlayer shearing performance testing. The bottleneck problem in the aspect of testing the interlayer shear strength of the composite material in a specific small area in the current composite material industry is solved, an important testing means is provided for research and development of the composite material, and experiments prove that the measurement repeatability error of the system is smaller than 2%, the standard requirement is completely met, and the system has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the technical field of materials mechanics testing equipment, and relates to a system and method for testing the mechanical properties of small regions of composite material structures. Background Technology

[0002] With the widespread application of composite materials in aerospace, automotive manufacturing, civil engineering, and other fields, the demand for accurate testing of their mechanical properties is increasing. Traditional methods for testing the mechanical properties of composite materials mainly target macroscopic specimens, such as the tensile test specified in ASTM D3039 and the bending test specified in ASTM D790. However, in practical engineering applications, composite material structures often have microscopic stress concentration regions, and the mechanical properties of these regions have a significant impact on the safety and reliability of the overall structure. Current technologies for testing the mechanical properties of micro-regions of composite materials face the following technical challenges: First, the size and loading capacity of traditional testing equipment are unsuitable for testing micro-samples; second, the preparation and clamping of micro-samples are difficult, easily leading to stress concentration during testing; third, existing technologies struggle to accurately control the loading and measurement of micro-regions, resulting in insufficient repeatability and accuracy of test results. For example, Chinese invention publication CN105181450A discloses a composite material mechanical property testing device, but its minimum testing area is only 1 cm. 2 This approach cannot meet the testing needs at smaller scales. Furthermore, in interlaminar shear performance testing, existing techniques such as the short beam shear test (ASTM D2344) suffer from uneven stress distribution, making it difficult to accurately reflect the true mechanical properties of small areas. Although some studies have attempted to use nanoindentation technology for microscopic mechanical property testing, this method only obtains local hardness information and cannot comprehensively characterize the mechanical properties of composite materials.

[0003] Therefore, developing a system and method capable of accurately detecting the mechanical properties of small regions in composite material structures is of great significance for improving the design level and safety assessment of composite material structures. Summary of the Invention

[0004] The present invention aims to solve the above-mentioned technical problems and provide a system and method for testing the mechanical properties of small areas of composite material structures.

[0005] The technical solution adopted in this invention is as follows:

[0006] A system for testing the mechanical properties of micro-regions in composite material structures includes a fixed base 1 and a testing device 2. The fixed base 1 has a clamping device 1.2 for fixing micro-samples and transmitting the force generated by the testing device 2 to the micro-samples. The testing device 2 has a pressure plate 2.4.12, whose movement is controlled by a servo motor 2.4.5, applying force to the micro-samples fixed within the clamping device 1.2. An improved short-beam shearing method is used to test the interlaminar shear properties. Specifically:

[0007] The fixed base 1 includes a workbench 1.1 and a clamping device 1.2. The clamping device 1.2 is fixed on the top of the workbench 1.1. One side of the small test piece is clamped and fixed on the clamping device 1.2 to ensure that it does not slip during the test. The other side protrudes from the clamping device 1.2 for the test equipment 2 to apply force.

[0008] The test equipment 2 includes a base plate 2.1, adjustable anchor bolts 2.2, support guide columns 2.3, control equipment 2.4, and displacement control system.

[0009] The base plate 2.1 has support guide columns 2.3 fixed at both ends of its upper surface. The workbench 1.1 of the fixed base 1 is fixed in the middle of the upper surface of the base plate 2.1. Adjustable anchor bolts 2.2 are provided at the four corners of the lower surface of the base plate 2.1 to keep the test equipment 2 in a horizontal state, thereby ensuring the stability of the test process.

[0010] The control device 2.4 includes a crossbeam plate 2.4.1, an outer casing 2.4.2, a touch screen all-in-one machine 2.4.3, a motor plate 2.4.4, a servo motor 2.4.5, a motor support 2.4.6, a small pulley 2.4.7, a large pulley 2.4.8, a ball screw 2.4.9, a locking nut 2.4.10, a positioning block 2.4.11, and a pressure plate 2.4.12; the crossbeam plate 2.4.1 is fixed to the top of two supporting guide columns 2.3, with a central hole in which the locking nut 2.4.10 is installed; the outer casing 2. 4.2 Fixed to the crossbeam plate 2.4.1, serving as the outer casing of the entire control equipment, the touch screen all-in-one machine 2.4.3 is embedded in the outer casing 2.4.2 for adjusting test parameters and monitoring the shear force in real time; the motor plate 2.4.4 is fixed next to the center hole of the crossbeam plate 2.4.1, and the servo motor 2.4.5 is fixed to the motor plate 2.4.4 via the motor support 2.4.6. A small pulley 2.4.7 is installed at the output end of the servo motor 2.4.5; the ball screw 2.4.9 passes through the center hole of the crossbeam plate 2.4.1, the center hole The locking nut 2.4.10 inside the screw 2.4.9 confines it within the central hole, allowing it to move up and down. The large pulley 2.4.8 is connected to the upper part of the screw 2.4.9 via a key. The small pulley 2.4.7 and the large pulley 2.4.8 are connected by a belt drive, forming a transmission device to achieve speed reduction control of the servo motor 2.4.5. The lower end of the screw 2.4.9 is connected to the positioning block 2.4.11, which in turn controls the pressure plate 2.4.1 below it. 2. Positioning is performed, and the pressure plate 2.4.12 applies force to the tiny specimen exposed outside the clamping device 1.2, causing it to break; the displacement control system is used to measure relevant values ​​during the fracture process of the tiny specimen and automatically analyze the mechanical parameter results; the servo motor 2.4.5 drives the small pulley 2.4.7 to rotate, and then drives the large pulley 2.4.8 to rotate through the belt. The rotation of the large pulley 2.4.8 is converted into the up and down movement of the lead screw 2.4.9, which in turn causes the pressure plate 2.4.12 to apply force to the tiny specimen fixed inside the clamping device 1.2.

[0011] Furthermore, the size of the micro specimen is within the range of 2mm×2mm×2mm.

[0012] Furthermore, the fixed base 1 is made of aerospace-grade 7075 aluminum alloy material and is formed by CNC machining.

[0013] Furthermore, the base plate 2.1 adopts a honeycomb sandwich structure design, which optimizes weight while ensuring load-bearing capacity.

[0014] A method for testing the mechanical properties of micro-regions in composite material structures, based on the aforementioned mechanical property testing system, includes the following steps:

[0015] Step 1: Prepare standard micro-samples using a high-precision micro-cutting device, with the sample size controlled within the range of 2mm×2mm×2mm.

[0016] Step 2: Fix the prepared micro sample onto the clamping device 1.2 to ensure that the sample does not slip during the test; set the detection parameters through the touch screen all-in-one machine 2.4.3.

[0017] Step 3: The servo motor 2.4.5 drives the large pulley 2.4.8 to rotate via the small pulley 2.4.7. The rotation of the large pulley 2.4.8 is converted into the up-and-down movement of the lead screw 2.4.9, which in turn causes the pressure plate 2.4.12 to move downwards and apply force to the small specimen exposed outside the clamping device 1.2. An improved short beam shearing method is used until the small specimen fractures, completing the interlaminar shear performance test. The entire test process optimizes the loading method through finite element analysis to ensure the uniformity of stress distribution.

[0018] Step 4: The displacement control system accurately measures the displacement of the fibers within the composite material during the fracture process. After the test is completed, the displacement control system automatically analyzes the load-displacement curve. The test results are processed and visualized using specialized software, and mechanical parameters such as stress-strain curves, failure mode analysis, elastic modulus, yield strength, and fracture toughness are calculated.

[0019] Furthermore, in step 1, the preparation process of the standard micro-sample is as follows: first, the composite material is cut using a diamond wire saw, and then the micro-sample is precision-machined using an ultra-short pulse laser.

[0020] The beneficial effects of this invention are as follows: It solves the current bottleneck problem in the composite materials industry regarding the testing of interlaminar shear strength in specific micro-regions of composite materials, providing an important testing method for composite material research and development in fields such as aerospace and automotive manufacturing. Experimental verification shows that the system's measurement repeatability error is less than 2%, fully meeting standard requirements and demonstrating broad application prospects. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the mechanical performance testing system.

[0022] Figure 2 for Figure 1 The main view;

[0023] Figure 3 for Figure 1 A partial structural diagram.

[0024] In the diagram: 1 Fixed base; 1.1 Workbench; 1.2 Clamping device; 2 Testing equipment; 2.1 Base plate; 2.2 Adjustable anchor bolts; 2.3 Support guide column; 2.4 Control equipment; 2.4.1 Crossbeam plate; 2.4.2 Outer casing; 2.4.3 Touch screen all-in-one machine; 2.4.4 Motor board; 2.4.5 Servo motor; 2.4.6 Motor support column; 2.4.7 Small pulley; 2.4.8 Large pulley; 2.4.9 Ball screw; 2.4.10 Locking nut; 2.4.11 Positioning block; 2.4.12 Pressure plate. Detailed Implementation

[0025] The technical solution of the present invention will now be clearly and completely described. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments derived by those skilled in the art based on the embodiments of the present invention through modifications or adjustments are within the protection scope of the present invention.

[0026] A system for testing the mechanical properties of small regions of composite material structures includes a fixed base 1 and a testing device 2, such as... Figures 1 to 3 .

[0027] The fixed base 1 is made of aerospace-grade 7075 aluminum alloy and is formed by CNC machining. It includes a workbench 1.1 and a clamping device 1.2. The clamping device 1.2 is fixed on the top of the workbench 1.1. One side of it is a fixed end and the other side is a movable end. One side of the small test piece is clamped and fixed on the fixed end to ensure that it does not slip during the test. The other side is placed on the movable end for the test equipment 2 to apply force.

[0028] The test equipment 2 includes a base plate 2.1, adjustable anchor bolts 2.2, support guide columns 2.3, control equipment 2.4, and displacement control system.

[0029] The base plate 2.1 adopts a honeycomb sandwich structure design, which optimizes the weight while ensuring the load-bearing capacity. Support guide columns 2.3 are fixed at both ends of its upper surface. The workbench 1.1 of the fixed base 1 is fixed in the middle of the upper surface of the base plate 2.1. Adjustable anchor bolts 2.2 are provided at the four corners of the lower surface of the base plate 2.1 to keep the test equipment 2 in a horizontal state, thereby ensuring the stability of the test process.

[0030] The control device 2.4 includes a crossbeam plate 2.4.1, an outer casing 2.4.2, a touch screen all-in-one machine 2.4.3, a motor plate 2.4.4, a servo motor 2.4.5, a motor support 2.4.6, a small pulley 2.4.7, a large pulley 2.4.8, a ball screw 2.4.9, a locking nut 2.4.10, a positioning block 2.4.11, and a pressure plate 2.4.12; the crossbeam plate 2.4.1 is fixed to the top of two support guide columns 2.3, with a central hole in which the locking nut 2.4.10 is installed; the outer casing... The housing 2.4.2 is fixed to the crossbeam plate 2.4.1, serving as the outer shell of the entire control device. The touch screen all-in-one machine 2.4.3 is embedded inside the outer housing 2.4.2 for adjusting test parameters and monitoring the shear force in real time. The motor plate 2.4.4 is fixed next to the center hole of the crossbeam plate 2.4.1. The servo motor 2.4.5 is fixed to the motor plate 2.4.4 via the motor support 2.4.6. A small pulley 2.4.7 is installed at the output end of the servo motor 2.4.5. The ball screw 2.4.9 passes through the center of the crossbeam plate 2.4.1. A locking nut 2.4.10 inside the central hole confines the ball screw 2.4.9 within the central hole, allowing it to move up and down. A large pulley 2.4.8 is connected to the upper part of the ball screw 2.4.9 via a key. A belt drive connects the small pulley 2.4.7 and the large pulley 2.4.8, thus achieving speed reduction control for the servo motor 2.4.5. The lower end of the ball screw 2.4.9 is connected to a positioning block 2.4.11, which positions the pressure plate 2.4.12 below it. 2. The force is applied to the moving end of the clamping device 1.2, causing the tiny specimen exposed on the moving end to break; the displacement control system is used to measure the relevant values ​​during the fracture process of the tiny specimen and automatically analyze the mechanical parameter results; the servo motor 2.4.5 drives the small pulley 2.4.7 to rotate, and then drives the large pulley 2.4.8 to rotate through the belt. The rotation of the large pulley 2.4.8 is converted into the up and down movement of the lead screw 2.4.9, which in turn causes the pressure plate 2.4.12 to apply force to the tiny specimen fixed in the clamping device 1.2.

[0031] A method for testing the mechanical properties of micro-regions in composite material structures includes the following steps:

[0032] Step 1: Prepare standard micro-samples using a high-precision micro-cutting device. The sample size is controlled within the range of 2mm×2mm×2mm. The preparation process is as follows: First, use a diamond wire saw to cut the composite material, and then use an ultra-short pulse laser to perform precision machining on the micro-samples.

[0033] Step 2: Fix the prepared micro sample on the fixed end of the clamping device 1.2 to ensure that the sample does not slip during the test; set the detection parameters through the touch screen all-in-one machine 2.4.3.

[0034] Step 3: The servo motor 2.4.5 drives the large pulley 2.4.8 to rotate via the small pulley 2.4.7. The rotation of the large pulley 2.4.8 is converted into the up-and-down movement of the lead screw 2.4.9, which in turn causes the pressure plate 2.4.12 to apply force to the micro-sample exposed on the moving end of the clamping device 1.2. An improved short beam shearing method is used until the micro-sample fractures, completing the interlaminar shear performance test. The entire test process optimizes the loading method through finite element analysis to ensure the uniformity of stress distribution.

[0035] Step 4: The displacement control system precisely measures the displacement of the fibers within the composite material during fracture. After the test, the displacement control system automatically analyzes the load-displacement curve. The test results are processed and visualized using specialized software, calculating mechanical parameters such as stress-strain curves, failure mode analysis, elastic modulus, yield strength, and fracture toughness. The entire testing process is automated under computer control, with a user-friendly interface and good repeatability of test results, meeting the requirements for precise testing of the mechanical properties of composite materials in minute areas.

[0036] The above-described embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A system for testing the mechanical properties of micro-regions in composite material structures, characterized in that, The test includes a fixed base (1) and a test device (2). The fixed base (1) is equipped with a clamping device (1.2) for fixing the micro specimen and transmitting the force generated by the test device (2) to the micro specimen. The test device (2) is equipped with a pressure plate (2.4.12), which is controlled by a servo motor (2.4.5) to move and apply force to the micro specimen fixed in the clamping device (1.2). The interlaminar shear performance test is carried out using an improved short beam shearing method.

2. The composite material structure micro-region mechanical property testing system according to claim 1, characterized in that, The specific structure is as follows: The fixed base (1) includes a workbench (1.1) and a clamping device (1.2). The clamping device (1.2) is fixed on the top of the workbench (1.1). One side of the small specimen is clamped and fixed on the clamping device (1.2), and the other side protrudes outside the clamping device (1.2). The test equipment (2) includes a base plate (2.1), a support guide column (2.3), a control device (2.4), and a displacement control system; The base plate (2.1) has support guide columns (2.3) fixed at both ends of its upper surface, and the workbench (1.1) of the fixed base (1) is fixed in the middle of the upper surface of the base plate (2.1); The control device (2.4) includes a crossbeam plate (2.4.1), an outer casing (2.4.2), a touch screen all-in-one machine (2.4.3), a servo motor (2.4.5), a ball screw (2.4.9), a positioning block (2.4.11), a pressure plate (2.4.12), and a transmission device; the crossbeam plate (2.4.1) is fixed to the top of two support guide columns (2.3), with a central hole therein, and the ball screw (2.4.9) is confined within the central hole of the crossbeam plate (2.4.1); the outer casing (2.4.2) is fixed to the crossbeam plate (2.4.1) and serves as the outer shell of the entire control device, and the touch screen all-in-one machine (2.4.3) is embedded in the outer casing. 2.4.2) Inside; the servo motor (2.4.5) is fixed next to the center hole of the crossbeam plate (2.4.1), and its output end is connected to the ball screw (2.4.9) through the transmission device to provide power to the ball screw (2.4.9); the lower end of the ball screw (2.4.9) is connected to the positioning block (2.4.11), and the positioning block (2.4.11) positions the pressure plate (2.4.12) below it. The pressure plate (2.4.12) applies force to the tiny specimen exposed outside the clamping device (1.2) to cause it to break; the displacement control system is used to measure the relevant values ​​during the tiny video fracture process and automatically analyze the mechanical parameter results.

3. The composite material structure micro-region mechanical property testing system according to claim 2, characterized in that, The fixed base (1) is made of aluminum alloy material and formed by CNC machining.

4. The composite material structure micro-region mechanical property testing system according to claim 2, characterized in that, The base plate (2.1) has adjustable anchor bolts (2.2) at the four corners of its lower surface to keep the test equipment (2) horizontal.

5. The composite material structure micro-region mechanical property testing system according to claim 2, characterized in that, The base plate (2.1) adopts a honeycomb sandwich structure design.

6. The composite material structure micro-region mechanical property testing system according to claim 2, characterized in that, The transmission device includes a small pulley (2.4.7) and a large pulley (2.4.8); the small pulley 2.4.7 is installed at the output end of the servo motor (2.4.5), and the large pulley (2.4.8) is connected to the ball screw (2.4.9). The small pulley (2.4.7) and the large pulley (2.4.8) are driven by a belt, thereby realizing the deceleration control of the servo motor (2.4.5).

7. The composite material structure micro-region mechanical property testing system according to claim 2, characterized in that, The dimensions of the micro specimen are 2mm × 2mm × 2mm.

8. A method for testing the mechanical properties of micro-regions in composite material structures, implemented based on the mechanical property testing system for micro-regions in composite material structures according to any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Prepare standard micro-samples using a high-precision micro-cutting device; Step 2: Fix the prepared micro-sample onto the clamping device (1.2); set the detection parameters via the touch screen all-in-one machine (2.4.3); Step 3: The servo motor (2.4.5) operates, causing the pressure plate (2.4.12) to move down and apply force to the small specimen exposed outside the clamping device (1.2) until the small specimen breaks, thus completing the interlaminar shear performance test. Step 4: The displacement control system accurately measures the displacement of the fibers in the composite material during the fracture process. After the test is completed, the load-displacement curve is automatically analyzed, and the test results are processed and visualized.

9. The method for testing the mechanical properties of micro-regions in a composite material structure according to claim 8, characterized in that, In step 1, the preparation process of the standard micro-sample is as follows: first, the composite material is cut using a diamond wire saw, and then the micro-sample is precision-machined using an ultra-short pulse laser.

10. The method for testing the mechanical properties of micro-regions in a composite material structure according to claim 8, characterized in that, In step 3, the loading method is optimized through finite element analysis to ensure the uniformity of stress distribution during the test.

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