Self-assembly surface instability structure complex stress loading device

Abstract

A complex stress loading device for self-assembled surface unstable structures includes: a fully automated triaxial displacement platform, an indenter mounted thereon, and an axially pressurizing fixture positioned opposite to it. The indenter is fixed to the Z-axis displacement stage of the triaxial displacement platform and serves as an intermediary for applying external force to the sample under test. This invention can be used for multi-dimensional detection, is simple and controllable to operate, and provides accurate test results. It meets the requirements for current testing and experimentation of self-assembled surface unstable micro / nano-folded structures. The axially pressurizing fixture, fully automated triaxial displacement platform, and replaceable indenter enable the clamping of self-assembled surface unstable structure samples and the application of external forces. It can also be directly used in conjunction with a super-depth-of-field optical microscope for loading tests on self-assembled surface unstable structures.

Description

Technical Field

[0001] This invention relates to a technology in the field of materials testing, specifically a stress loading device for a complex self-assembled surface instability structure. Background Technology

[0002] Surface instability-induced mechanical self-assembly of micro / nano-folded structures is an important form of functional surface construction. Existing equipment cannot apply the axial compressive load required to induce instability in hard-film soft-substrate composite structures, and lacks structural support for real-time, continuous optical observation of the morphological evolution of the sample's XZ plane, i.e., the fold depth direction, during complex stress loading, making it difficult to continuously record the dynamic evolution of unstable structures. Summary of the Invention

[0003] To address the aforementioned shortcomings of existing technologies, this invention proposes a complex stress loading device for self-assembled surface unstable structures. This device can measure multiple dimensions, is simple and controllable to operate, and provides accurate test results. It can meet the requirements of current testing and experimentation of self-assembled surface unstable micro / nano wrinkled structures. Through axial pressure clamps, a fully automatic triaxial displacement platform, and replaceable pressure heads, it achieves the clamping of self-assembled surface unstable structure samples and the application of external forces. It can also be directly used with an ultra-depth-of-field optical microscope to perform loading tests on self-assembled surface unstable structures.

[0004] This invention is achieved through the following technical solution:

[0005] This invention relates to a complex stress loading device for a self-assembled surface instability structure, comprising: a fully automatic triaxial displacement platform and a pressure head disposed thereon and an axial pressure clamp disposed opposite to it, wherein: the pressure head is fixed on the Z-axis displacement stage of the triaxial displacement platform and is used as an intermediary to apply external force to the sample to be tested.

[0006] The test sample is a hard film and soft substrate double-layer structure with high modulus PDMS (184) as thin film and low modulus PDMS (C-0030) as substrate. It is a self-assembled surface unstable structure. It is a cuboid in the absence of external stress. After applying axial stress, a uniform wrinkled structure is generated on the surface. The surface has weak adhesion and can be tightly attached to the support block.

[0007] The axial pressure fixture includes: a manual linear forward and reverse thread slide, a compression block, and a support block. Each compression block is fixed to the manual linear forward and reverse thread slide by bolts. Its shape ensures that the compressive stress is applied only to the upper half of the sample to be tested, preventing overall buckling and central bulging. The support block is fitted into the lead screw of the manual linear forward and reverse thread slide and fits tightly against the sample to be tested, thereby fixing the sample to be tested.

[0008] The end of the indenter is a cuboid or semi-cylinder of different sizes with a long cantilever beam, used to investigate the influence of square and semi-circular distributed external loads on the morphology of the sample under test.

[0009] Technical effect

[0010] This invention constructs an axial pressure fixture by using a support block that can be fitted into a lead screw and a manually operated linear forward and reverse threaded slide. A fully automated three-axis displacement platform is used to mount a pressure head with a long cantilever beam design, and the side of the axial pressure fixture is fixed to the microscope stage, ensuring that the motion axis of the three-axis displacement platform is specifically aligned with the fixture's coordinate system. Compared to existing technologies, this invention is directly compatible with ultra-depth-of-field optical microscopes, solving the problem that traditional devices cannot perform real-time observation on the XZ section. Through precise control of the fully automated platform, accurate loading of normal compressive stress and horizontal sliding force is achieved on the hard-film soft-substrate double-layer sample. Experiments show that this device can clearly capture and quantify the evolution of wrinkle depth with external force, significantly improving the stability of the test and the accuracy of the data compared to traditional manual devices. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of the present invention;

[0012] In the figure: 1. Manual linear forward and reverse toothed slide, 2. Compression block, 3. Support block, 4. Pressure head, 5. Z-axis displacement stage, 6. Z-axis rotary stage, 7. XY-axis displacement stage, 8. Sample to be tested;

[0013] Figure 2 This is a schematic diagram of a compressed block;

[0014] Figure 3 This is a schematic diagram of the support block;

[0015] Figure 4 This is a schematic diagram of the pressure head;

[0016] Figure 5 This is a schematic diagram of a scenario for an example embodiment;

[0017] In the figure: eyepiece 9 and microscope stage 10 of the optical microscope;

[0018] Figure 6 This is a photograph of the anti-buckling effect of the axial pressure clamp of the present invention when compressing the sample to be tested;

[0019] Figure 7 This is an XZ plane fold morphology evolution diagram recorded at compression depths of 0 mm, 0.5 mm, 1.0 mm, and 2.0 mm, respectively. Detailed Implementation

[0020] like Figure 1As shown in the figure, this embodiment relates to a complex stress loading device for a self-assembled surface instability structure, including: a fully automatic triaxial displacement platform and a pressure head 4 disposed thereon and an axial pressure clamp disposed opposite to it, wherein: the pressure head 4 is fixed on the Z-axis displacement stage of the triaxial displacement platform and is used as an intermediary to apply external force to the sample to be tested.

[0021] The axial pressure fixture includes: a manual linear forward and reverse thread slide 1, a compression block 2, and a support block 3. The two compression blocks 2 are symmetrically fixed to the left and right sliders of the manual linear forward and reverse thread slide 1 by bolts, and move relative to the sliders to compress the sample to be tested. The support block 3 is installed above the lead screw at the bottom of the manual linear forward and reverse thread slide 1, between the two compression blocks 2, and is used to support and fix the sample to be tested.

[0022] like Figure 2 As shown, the compression block 2 adopts a stepped structure, with a protruding contact surface a at the upper front and a recessed notch b at the lower front. During loading, the protruding contact surface a only abuts against the upper half of the sample to be tested (i.e., the upper part of the thin film layer and the substrate layer), while the recessed notch b at the lower part maintains a gap with the lower half of the sample to be tested (i.e., the lower part of the substrate layer), and no direct axial thrust is applied to the substrate.

[0023] like Figure 3 As shown, the bottom of the support block 3 is provided with a semi-circular groove c, which is directly fitted into the lead screw of the manual linear forward and reverse thread slide 1; the top surface of the support block 3 is a vertical bearing surface d, which is used to support and adsorb the sample to be tested, so that it remains in a fixed position as the lead screw moves.

[0024] like Figure 4 As shown, the end e of the pressure head 4 is a cuboid and a semi-cylinder used to investigate the influence of square and semi-circular distributed external loads on the morphology of the sample to be tested. The design of the long cantilever beam f reserves space for the entire device to be installed on the ultra-depth-of-field microscope.

[0025] The test sample is a hard film and soft substrate double-layer structure with high modulus PDMS (184) as thin film and low modulus PDMS (C-0030) as substrate. It is a self-assembled surface unstable structure. It is a cuboid in the absence of external stress. After applying axial stress, a uniform wrinkled structure is generated on the surface. The surface has weak adhesion and can be tightly attached to the support block.

[0026] The fully automatic three-axis displacement platform includes: XY axis displacement stage 7, Z axis rotary stage 6, and Z axis displacement stage 5 arranged sequentially from bottom to top. The Z axis displacement stage 5 is an automatic linear screw slide, which can achieve uniform and precise control through an external encoder. The rotary stage is a manual screw stage with angular scales and a minimum division value of 0.1 degrees, which can realize the translation of the upper pressure head along the X, Y, and Z axes and the rotation around the Z axis.

[0027] This embodiment relates to a complex stress loading method for the self-assembled surface instability structure of the above-mentioned device, including:

[0028] Step 1: Place the sample to be tested on the support block of the axial compression fixture, compress the sample to be tested at an appropriate strain rate to produce a wrinkled structure, and fix it in the test area at the same time.

[0029] Step 2, as follows Figure 5 As shown, the axial pressure fixture is fixed to the side of the microscope stage plane. The eyepiece 9 of the optical microscope is adjusted to be above the sample to be tested. The distance between the microscope stage 10 plane and the eyepiece is adjusted appropriately to ensure that the surface morphology changes of the sample can be clearly observed. The pressure head is fixed to the triaxial displacement platform with bolts. The X-axis and Y-axis of the triaxial displacement platform need to be coincident with the X-axis and Z-axis of the axial pressure fixture, respectively. At the same time, the Z-axis of the triaxial displacement platform is adjusted to determine the angle and position of the pressure head, ensuring that the pressure head faces the sample surface and is perpendicular to the sample surface.

[0030] The microscope stage 10 is used to support and fix the axial pressure fixture, wherein the X-axis and Y-axis of the axial pressure fixture are in the same direction as the X-axis and Z-axis of the triaxial displacement platform, respectively.

[0031] Step 3: Control the triaxial displacement platform to translate along the Y-axis to apply normal compressive stress to the sample, and translate along the X-axis to apply horizontal sliding force. Adjust the lens above the sample to capture the deformation pattern and record the morphological evolution of the sample on its XZ plane as the compression depth changes. This completes the loading test.

[0032] Through specific experiments, by subjecting the test sample to axial compression, the lower part of the substrate layer was not directly pushed axially due to the reserved space of the relief notch. The experiment showed that when the compressive strain reached 20%, uniform micro-nano wrinkles evolved on the sample surface (such as...). Figure 6 As shown in the figure, this effectively avoids the overall buckling and central bulge problems easily caused by traditional flat-jaw fixtures. Furthermore, a triaxial displacement platform is used to control the indenter, which translates along the Y-axis at a constant rate of 0.5 mm / s to apply normal compressive stress to the sample under test. The experiment recorded the XZ plane morphology evolution images of the sample under test at indentation depths of 0 mm, 0.5 mm, 1.0 mm, and 2.0 mm (as shown in the figure). Figure 7 (As shown). Through these clear images at different depths, the specific depth and morphological changes of the folds in the Z direction can be observed and quantified. For example, when the compressive depth increases from 0 to 1.0 mm, the fold amplitude at the indenter in the XZ plane is measured to evolve from 0.0619 mm to 0.0202 mm. This successfully breaks through the technical bottleneck of traditional experimental devices that can only observe the XY plane and are difficult to quantify the evolution law in the Z direction.

[0033] Compared with existing technologies, this invention significantly improves the accuracy and observation dimensions of loading tests by introducing stepped compression blocks, a fully automated three-axis displacement platform, and a long cantilever beam indenter.

[0034] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. A stress loading device for a complex self-assembled surface instability structure, characterized in that, include: The fully automatic triaxial displacement platform and the pressure head set on it, as well as the axial pressure clamp set opposite to it, wherein: the pressure head is fixed on the Z-axis displacement stage of the triaxial displacement platform and is used as an intermediary to apply external force to the sample to be tested.

2. The complex stress loading device for self-assembled surface instability structures according to claim 1, characterized in that, The test sample is a hard film and soft substrate double-layer structure with high modulus PDMS (184) as thin film and low modulus PDMS (C-0030) as substrate. It is a self-assembled surface unstable structure. It is a cuboid in the absence of external stress. After applying axial stress, a uniform wrinkled structure is generated on the surface. The surface has weak adhesion and can be tightly attached to the support block.

3. The complex stress loading device for self-assembled surface instability structures according to claim 1, characterized in that, The axial pressure fixture includes: a manual linear forward and reverse thread slide, a compression block, and a support block. Each compression block is fixed to the manual linear forward and reverse thread slide by bolts. Its shape ensures that the compressive stress is applied only to the upper half of the sample to be tested, preventing overall buckling and central bulging. The support block is fitted into the lead screw of the manual linear forward and reverse thread slide and fits tightly against the sample to be tested, thereby fixing the sample to be tested.

4. The complex stress loading device for self-assembled surface instability structures according to claim 1, characterized in that, The end of the indenter is a cuboid or semi-cylinder of different sizes with a long cantilever beam, used to investigate the influence of square and semi-circular distributed external loads on the morphology of the sample under test.

5. A method for loading complex stress onto a self-assembled surface instability structure of the device according to any one of claims 1-4, characterized in that, include: Step 1: Place the sample to be tested on the support block of the axial compression fixture, compress the sample to be tested at an appropriate strain rate to produce a wrinkled structure, and fix it in the test area at the same time. Step 2: Fix the side of the axial pressure fixture to the microscope stage plane. Adjust the eyepiece of the optical microscope to be above the sample to be tested. Adjust the distance between the microscope stage plane and the eyepiece appropriately to ensure that the surface morphology changes of the sample can be clearly observed. Fix the indenter to the triaxial displacement platform with bolts. The X-axis and Y-axis of the triaxial displacement platform should coincide with the X-axis and Z-axis of the axial pressure fixture, respectively. At the same time, adjust the Z-axis of the triaxial displacement platform to determine the angle and position of the indenter, ensuring that the indenter faces the sample surface and is perpendicular to the sample surface. Step 3: Control the triaxial displacement platform to translate along the Y-axis to apply normal compressive stress to the sample, and translate along the X-axis to apply horizontal sliding force. Adjust the lens above the sample to capture the deformation pattern and record the morphological evolution of the sample on its XZ plane as the compression depth changes. This completes the loading test.

Images