A small size core adapter device for MTS electronic universal testing machine

Abstract

The utility model discloses a small size rock core adaptive device for MTS electronic universal testing machine, by the arc gasket subassembly of 50.8mm of core outer diameter after superposition, the arc gasket subassembly of 38.1mm of core outer diameter after superposition, the cylindrical gasket block of slot, arc clamping knife edge, extensometer, threaded fastening device, chain and tensioning mechanism composition. The utility model two sets of arc gasket subassembly respectively with core outer diameter adapts to 50.8mm and 38.1mm;Through two sets of arc gasket contrast measurement identification system error;The cylindrical gasket block of slot sets up in the rock core bottom, is used for compensating height;Arc clamping knife edge and extensometer are integral, realize the self -adaptation of gasket subassembly clamping. The utility model simple structure, low in cost, convenient operation can effectively solve the problem that small size rock core can not adapt standard extensometer, significantly improve the accuracy and reliability of small size rock core mechanical property test.

Description

Technical Field

[0001] This utility model relates to the technical field of rock mechanical property testing equipment, specifically to a small-sized core adapter for an MTS electronic universal testing machine, which is particularly suitable for testing the mechanical properties of core samples with a diameter of 25.4 mm and a height of 50.8 mm. Background Technology

[0002] In geotechnical engineering fields such as oil and gas extraction, geological hazard assessment, and tunnel and slope stability analysis, the tensile strength, Young's modulus, and Poisson's ratio of rock are key mechanical parameters for evaluating rock mass stability and designing engineering schemes. Uniaxial tensile testing is one of the most direct and reliable methods for obtaining these parameters, typically using an electronic universal testing machine (such as the MTS system) in conjunction with an extensometer for precise measurement. However, standard extensometers are usually designed to hold standard core samples of specific sizes (e.g., 50 mm in diameter and 100 mm in height). In actual research, due to wear during drilling, heterogeneity of rock mass structure, or special experimental requirements, core samples with diameters or heights smaller than the standard are often obtained. For example, cores with a diameter of 25.4 mm and a height of 50.8 mm are common under certain special geological conditions or sampling limitations. For such small-sized cores, standard extensometers cannot effectively hold or measure them, leading to inaccurate data, experimental failure, and even potential equipment damage.

[0003] Currently, there are few adaptation solutions for small-sized cores. Typically, custom-made fixtures or modifications to the extensometer are required, but these methods are costly, lack versatility, and may introduce additional systematic errors. Therefore, there is an urgent need in this field for an adaptation device that is simple in structure, low in cost, and easy to operate, to expand the applicability of standard extensometers and improve the accuracy and reliability of experimental data from small-sized cores. Utility Model Content

[0004] The purpose of this utility model is to provide a small-sized core fitting device for the MTS electronic universal testing machine, which solves the problem that cores with a diameter of 25.4 mm and a height of 50.8 mm cannot be fitted with standard extensometer clamps.

[0005] The technical solution of this utility model is as follows: a small-sized core fitting device for an MTS electronic universal testing machine, including an arc-shaped gasket assembly with an outer diameter of 50.8 mm after stacking, an arc-shaped gasket assembly with an outer diameter of 38.1 mm after stacking, a cylindrical gasket with a slot, an arc-shaped clamping blade, an extensometer, a threaded fastening device, a chain, and a tensioning mechanism.

[0006] Preferably, the arc-shaped shim assembly consists of six arc-shaped 430 stainless steel shims with a gap of 0.5–1 mm between them. This material is magnetic, facilitating individual operation, and also allows the shims to better conform to the curved surface of the core sample, improving measurement accuracy.

[0007] Preferably, after the two sets of gasket assemblies are used, the outer diameter of the core is adjusted to 50.8 mm and 38.1 mm respectively. By comparing the Poisson's ratio measured in the two states, the systematic error introduced by the gap or poor contact between the gasket and the clamping blade can be identified and quantified.

[0008] Preferably, the cylindrical pad with the slot is made of 60Si2Mn steel, and the top is provided with a slot for fixing the rock core, compensating for the insufficient height of non-standard specimens, and ensuring effective clamping of the extensometer.

[0009] Preferably, the arc-shaped clamping blade has an arc-shaped structure, which can achieve adaptive clamping of core samples of different diameters.

[0010] The beneficial effects of this utility model are as follows:

[0011] (1) The experimental device of this utility model has a simple structure, low cost, and is easy to promote; it is safe and convenient to operate and can effectively measure the mechanical properties of rock cores with a diameter of 25.4 mm and a height of 50.8 mm.

[0012] (2) This utility model uses two sets of arc-shaped gasket assemblies to effectively identify system errors by comparing measurement results; the arc-shaped clamping blade cooperates with the gasket to improve clamping stability and data accuracy; the cylindrical gasket with a slot is used to compensate for height and ensure the extensometer gauge length requirements.

[0013] (3) When this utility model is used, it presents a strict coaxial, radially layered and axially superimposed structure with the rock core axis as the reference: the rock core is tightly wrapped by the inner layer gasket assembly, and the outer layer is held by the chain radial clamping and the extensometer arc clamping blade; the rock core is embedded in the top of the cylindrical pad with the groove, and its axial position is compensated for and fixed by the cylindrical pad with the groove; finally, the whole set of devices is installed on the fixture seat, and the experiment can be carried out. Attached Figure Description

[0014] Figure 1 The above are the front and top views of this utility model with an arc-shaped gasket up to a diameter of 50.8 mm.

[0015] Figure 2 The above are the front and top views of this utility model with an arc-shaped gasket up to a diameter of 38.1 mm.

[0016] Figure 3 The front and top views of the cylindrical pad with slots of this utility model are provided with an increased longitudinal height.

[0017] Figure 4 These are the front and top views of the arc-shaped clamping blade of this utility model.

[0018] Figure 5 These are the front and top views of the chain and tensioning mechanism of this utility model.

[0019] Reference numerals in the attached figures: 1 is an arc-shaped shim with an outer diameter of 50.8 mm after stacking; 2 is an arc-shaped shim with an outer diameter of 38.1 mm after stacking; 3 is a cylindrical shim with a groove; 4 is an arc-shaped clamping blade; 5 is an extensometer; 6 is a threaded fastening device; 7 is a chain and tensioning mechanism. Detailed Implementation

[0020] The embodiments of the present invention will be further described below with reference to the accompanying drawings, but this is not intended to limit the present invention.

[0021] Before describing the specific implementation of this utility model, in order to make the solution of this utility model clearer and more complete, some of the devices appearing in this utility model will be described first:

[0022] Arc-shaped shim assembly: Composed of six arc-shaped 430 stainless steel shims. This stainless steel is magnetic. An arc-shaped shim assembly with a single shim thickness of 12.7 mm allows for a core outer diameter fit up to 50.8 mm, while an arc-shaped shim assembly with a single shim thickness of 6.4 mm allows for a core outer diameter fit up to 38.1 mm. A gap of 0.5–1 mm is left between the shims, the width of which matches the width of the clamping blades (15 mm).

[0023] Cylindrical pad: Made of 60Si2Mn steel, with a slot at the top for fixing the rock core.

[0024] Arc-shaped clamping blade: This is an optimized clamping component for the extensometer. This optimized component is integrally formed with the original clamping end of the extensometer, and its arc-shaped clamping opening can adapt to rock core samples of different diameters. The extensometer, as the core of strain measurement, converts the micro-strain of the rock core into electrical signals through an LVDT displacement sensor. The threaded locking device achieves micron-level feed, and the torque control ensures constant clamping force. It has a double self-locking design to prevent loosening during the experiment. The chain and tensioning mechanism circumferentially surround the gasket assembly and transmit the tension force generated by the threaded locking device for measuring Poisson's ratio.

[0025] This utility model patent describes a small-sized core fitting device for an MTS electronic universal testing machine. The device includes: an arc-shaped gasket assembly with an outer diameter of 50.8 mm after stacking cores, an arc-shaped gasket assembly with an outer diameter of 38.1 mm after stacking cores, a cylindrical gasket with a slot, an arc-shaped clamping blade, an extensometer, a threaded fastening device, a chain, and a tensioning mechanism.

[0026] Six 430 stainless steel washers are magnetically connected and surround the core at half its height, with a 0.5-1mm gap between adjacent washers. The washers are connected to the 25.4mm diameter core via a top slot and placed below it. The washer assembly is secured by a chain and tensioning mechanism. The arc-shaped clamping opening above it is connected to the extensometer via a threaded fastening device.

[0027] Operating steps:

[0028] (1) Use electronic vernier calipers to measure the actual diameter and height of the core and record the original data;

[0029] (2) Install the first set of gaskets (fitting diameter 50.8mm): Use magnetic adsorption to evenly wrap the six arc-shaped gaskets around the core at half the height, with a gap of 0.5–1mm between each gasket. Lock the chain to the outer circumference of the core wrapped with gaskets and tension it to the predetermined torque. Secure it with a threaded device.

[0030] (3) If the core height is insufficient, place a cylindrical pad with a groove at the bottom of the core to make the total combined height meet the experimental requirements;

[0031] (4) First clamping of the extensometer: Align the arc-shaped clamping blade with the outer periphery of the core and install the threaded device to tighten it;

[0032] (5) Perform the first tensile test and collect axial and radial strain data;

[0033] (6) Based on the data from the first experiment, calculate the first Young's modulus (E1) and the first Poisson's ratio (V1);

[0034] (7) While maintaining the fixed relative position of the core and pad, assemble the second set of arc-shaped pad components with a diameter of 38.1 mm into the second assembly;

[0035] (8) Clamp the extensometer a second time, tension the chain with the same torque and fix it;

[0036] (9) Perform the second tensile test and collect the second set of strain data;

[0037] (10) Calculate the second Young's modulus (E2) and the second Poisson's ratio (V2);

[0038] (11) Data comparison and verification: The relative error in calculating Young's modulus: The relative error in calculating Poisson's ratio: If both δE and δV are ≤0.001, the arithmetic mean is taken as the final mechanical parameter; otherwise, the apparatus needs to be checked or the experiment repeated.

[0039] (12) After the experiment, disassemble each component in sequence and clean and put it back in place.

[0040] This invention combines six arc-shaped pads and cylindrical blocks to form a cylinder with an outer diameter conforming to the standard dimensions of an extensometer. Two sets of arc-shaped pads are used to measure Poisson's ratio for data comparison, improving the accuracy and reliability of experimental data. A grooved cylindrical block compensates for and fixes the core height. An arc-shaped clamping blade enables adaptive clamping, ensuring experimental safety. This device is low-cost and highly versatile; a single standard extensometer combined with multiple sets of pads can cover a wide range of sample size requirements. Furthermore, the device has a simple structure, is easy to operate, and can be completed independently by one person.

[0041] The foregoing description only illustrates certain exemplary embodiments of the present invention. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A small-sized core fitting device for an MTS electronic universal testing machine, characterized in that: The stacked core has an outer diameter of 50.8 mm and an outer diameter of 38.1 mm. The stacked core has an outer diameter of 38.1 mm. The stacked core has an outer diameter of 38.1 mm and ... Six 430 stainless steel arc-shaped gaskets (1) and (2) are connected by magnetism and surround the core at half its height, with a 0.5-1mm fixing gap between adjacent gaskets; a cylindrical gasket (3) with a slot is connected to the core with a diameter of 25.4mm, and the core is fixed by the slot and placed below it; the gasket assembly is tightened by a chain and tensioning mechanism (7); the arc-shaped clamping blade (4) is connected to the extensometer (5) through a threaded fastening device (6), with the upper blade clamping the outer wall of the core and the lower blade clamping the cylindrical gasket.

2. The small-sized core fitting device for an MTS electronic universal testing machine according to claim 1, characterized in that: The arc-shaped gasket assembly consists of six magnetic arc-shaped 430 stainless steel gaskets, with a gap of 0.5–1 mm between each gasket.

3. The small-sized core fitting device for an MTS electronic universal testing machine according to claim 1, characterized in that: The two sets of arc-shaped gasket assemblies are used to adjust the outer diameter of the core to 50.8 mm and 38.1 mm, respectively.

4. The small-sized core fitting device for an MTS electronic universal testing machine according to claim 1, characterized in that: The arc-shaped clamping blade has an arc-shaped structure, which can adaptively clamp core samples of different diameters.

5. A small-sized core fitting device for an MTS electronic universal testing machine according to claim 1, characterized in that: The cylindrical pad is made of 60Si2Mn steel and has a slot on the top.

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