CN111912700B - Transverse displacement compensation device and method for testing foam shearing performance - Google Patents
Transverse displacement compensation device and method for testing foam shearing performance Download PDFInfo
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Abstract
The invention discloses a transverse displacement compensation device for testing the shearing performance of foam, which comprises a force application mechanism, a metal clamping plate and a displacement compensation mechanism, wherein the force application mechanism comprises an upper pressure head, a lower pressure head and a connecting mechanism; the upper pressure head is of an L-shaped structure, one end of the upper pressure head is connected with a connecting rod of the connecting mechanism through a locking nut, and the other end of the upper pressure head is connected with the upper clamping plate through a fixing screw; the connecting mechanism comprises an upper connecting mechanism and a lower connecting mechanism, and a connecting joint of the mechanical testing machine is sleeved at one end of the connecting rod and fixedly connected with the connecting rod through a pin; the other end of the connecting rod is rigidly fixed with the pressure head through a locking nut. The invention solves the problem of inaccurate shear performance test caused by the transverse displacement and tensile stress generated by deformation of semi-rigid and soft foam materials, and improves the accuracy and reliability of test results by using the transverse displacement compensation test device and method for the shear performance of the foam materials.
Description
Technical Field
The invention relates to a transverse displacement compensation device and a method for testing foam shearing performance, and belongs to the field of material performance measurement and material engineering application.
Background
In recent years, rapid development of aerospace technologies such as manned space, deep space exploration and hypersonic aircrafts has put more and more application demands on thermal protection systems and thermal insulation materials. The space craft faces complex and variable high-temperature and low-temperature environments in rail service and world reciprocating processes, a large amount of thermal insulation materials are required to be used for carrying out thermal protection on the space craft outside, and the foam thermal insulation materials are used as a structure and function integrated material, have low thermal conductivity and certain mechanical bearing performance, are very suitable to be used as thermal insulation materials of the space craft, and have wide application prospects in novel solar wing substrates. The shear mechanical property is used as a key performance index of the foam material, and the shear mechanical property needs to be accurately measured, so that the technical difficulty in evaluating the performance of the foam material is formed.
The traditional method for measuring the shearing mechanical property of the foam material mainly adopts a test method in GB/T10007-2008 or ASTM C393-00 standards, mainly applies tensile stress to the foam material fixed in a clamp by using an upper force application mechanism and a lower force application mechanism, and realizes the measurement of the shearing strength or the shearing modulus of the material by using a tensile shearing method. Because the foam material can produce horizontal deformation in the test process, and two chucks of the force application mechanism are fixed in position and cannot be displaced and adjusted along with the horizontal deformation of the foam, a state that horizontal tensile stress and longitudinal shear stress coexist is formed, certain test errors are caused to the stress and strain test in a pure shear performance state, and the accuracy of a test result is low. The error increases with the increase of the deformation, the stress proportion and the tensile stress, so the traditional test method is mainly suitable for rigid foam materials, and has larger measurement error for shear performance test of semi-rigid and soft foam materials due to the lack of transverse displacement compensation.
In conclusion, the traditional foam material shearing performance test method is not suitable for semi-rigid and flexible foam materials with large deformation in the test process due to the existence of transverse displacement and transverse tensile stress in the tensile shearing process.
Disclosure of Invention
The invention solves the technical problems that: the invention provides a transverse displacement compensation device and a transverse displacement compensation method for testing foam shearing performance, solves the problem of inaccurate shearing performance test caused by transverse displacement and tensile stress generated by deformation of semi-rigid and soft foam materials, can accurately test the shearing performance of the semi-rigid and soft foam materials, and improves the test efficiency and the applicability.
The technical solution of the patent of the invention is as follows:
a transverse displacement compensation device for testing the shearing performance of foam comprises a force application mechanism, a metal clamping plate and a displacement compensation mechanism,
the force applying mechanism comprises an upper pressure head, a lower pressure head and a connecting mechanism,
the metal splint comprises an upper splint and a lower splint,
the displacement compensation mechanism comprises an upper guide rail, a lower guide rail and a rolling shaft;
the upper pressure head is of an L-shaped structure, one end of the upper pressure head is connected with a connecting rod of the connecting mechanism through a locking nut, and the other end of the upper pressure head is connected with the upper clamping plate through a fixing screw;
the connecting mechanism comprises an upper connecting mechanism and a lower connecting mechanism, the connecting mechanisms are respectively composed of a connecting rod, a locking nut and a pin, and a connecting joint of the mechanical testing machine is sleeved at one end of the connecting rod and fixedly connected with the connecting rod through the pin; the other end of the connecting rod is rigidly fixed with the pressure head through a locking nut;
the foam material test sample is adhered between the upper clamp plate and the lower clamp plate through an adhesive, the extension part of the metal clamp plate is fixedly connected with the upper pressure head through a fixing screw, and the lower clamp plate is fixedly connected with an upper guide rail in the displacement compensation mechanism;
the lower pressure head and the lower guide rail are integrally designed, and at least two parallel rolling shafts are arranged between the upper guide rail and the lower guide rail;
the lower pressure head is connected with a connecting rod of the lower connecting mechanism through a locking nut, and the lower connecting rod is connected with the mechanical testing machine through a pin; the upper guide rail of the displacement compensation mechanism can move along with the deformation of the foam material test sample to perform transverse compensation on the deformation.
Furthermore, the sections of the upper guide rail and the lower guide rail are both in an isosceles triangle structure, and the included angle between the waist of the triangle and the horizontal plate is 45 degrees.
Further, the determination method of the shear modulus of the foam material comprises the following steps:
in the formula: g is the shear modulus of the sample; δ is the thickness of the sample; theta is the slope of a straight line in the load-deformation diagram; l is the original length of the sample; b is the original width of the sample.
Further, the method for sticking the foam material test sample between the upper clamping plate and the lower clamping plate by the adhesive comprises the following steps: coating a layer of adhesive on the part, to which the sample is adhered, of the metal clamping plate in advance, so that the foam sample is adhered to the upper edge and the lower edge of the two clamping plates respectively, and after the adhesive is coated, oppositely placing the upper clamping plate and the lower clamping plate and staggering the upper clamping plate and the lower clamping plate for a certain distance; after the pasting is finished, a clamping plate with the same size as the upper clamping plate is added to the upper clamping plate to serve as a pressing plate, the upper clamping plate and the lower clamping plate translate for the same distance in the opposite direction, so that stress balance is achieved, then a balancing weight is added above the pressing plate, pressurization and solidification are carried out for at least 24 hours under the condition of normal temperature, and after sample solidification is finished, the upper clamping plate and the lower clamping plate are vertically placed with a table top to be free of any pressure.
A transverse displacement compensation method for testing the shearing performance of foam comprises the following steps:
the method comprises the following steps that firstly, an upper connecting rod and a lower connecting rod are respectively inserted into a connecting joint concave groove of a mechanical testing machine to be connected, one end of the upper connecting rod is fixedly connected with an upper connecting joint, the other end of the upper connecting rod is fixedly connected with an upper pressure head, and the upper connecting rod and the upper pressure head are rigidly fixed in the testing process through rotating a locking nut; the lower connecting mechanism enables the lower connecting rod and the lower pressure head to respectively achieve rigid fixed connection through the locking nut;
opening a mechanical testing machine, hoisting an upper clamping plate which is not adhered with a sample on the testing machine, and resetting the additional load brought by the testing plate; mounting the displacement compensation mechanism in place; respectively installing the metal clamping plates adhered with the foam test samples between the upper pressure head and the lower pressure head;
thirdly, applying a pressing shear stress to the foam test sample at a certain loading rate, namely applying a downward pressure to the upper clamping plate and applying an upward pressure to the lower clamping plate, wherein the foam material generates longitudinal and transverse deformation under the action of the shear stress, and the lower clamping plate drives the displacement compensation mechanism to horizontally move under the action of the transverse tensile stress to compensate the transverse displacement;
and step four, repeatedly loading the foam sample at a certain loading rate for three times, drawing a load-deformation curve, calculating the shear modulus in a linear section range, and continuously loading at a constant rate until the foam sample is broken to obtain the shear strength of the foam material.
Further, the method for adhering the sample on the metal splint comprises the following steps:
coating a layer of adhesive on the part, to which the sample is adhered, of the metal clamping plate in advance, so that the foam sample is adhered to the upper edge and the lower edge of the two clamping plates respectively, and after the adhesive is coated, oppositely placing the upper clamping plate and the lower clamping plate and staggering the upper clamping plate and the lower clamping plate for a certain distance; after the sample is cured, the upper clamping plate and the lower clamping plate are vertically placed on a table top to prevent the sample from being subjected to any pressure.
Furthermore, the displacement compensation mechanism comprises an upper guide rail, a lower guide rail and a rolling shaft; the lower clamping plate is fixedly connected with an upper guide rail in the displacement compensation mechanism;
the lower pressure head and the lower guide rail are integrally designed, and at least two parallel rolling shafts are arranged between the upper guide rail and the lower guide rail;
the upper guide rail of the displacement compensation mechanism can move along with the deformation of the foam material test sample to perform transverse compensation on the deformation.
Furthermore, the sections of the upper guide rail and the lower guide rail are both in an isosceles triangle structure, and the included angle between the waist of the triangle and the horizontal plate is 45 degrees.
Further, the determination method of the shear modulus of the foam material comprises the following steps:
in the formula: g is the shear modulus of the sample; δ is the thickness of the sample; theta is the slope of a straight line in the load-deformation diagram; l is the original length of the sample; b is the original width of the sample.
Further, in the third step, the foam test sample is applied with a compressive shear stress at a loading rate of 1-3mm/min, and in the fourth step, the foam test sample is repeatedly loaded three times at a loading rate of 1-3mm/min, and the loading is continued at a constant rate of 3-5mm/min until the foam test sample breaks.
Compared with the prior art, the invention has the beneficial effects that:
(1) According to the invention, by using the transverse displacement compensation test method for the shearing performance of the foam material, the shearing performance measurement error caused by transverse deformation and transverse tensile stress of the semi-rigid and soft foam materials is reduced, the stress process is closer to the pure shearing stress state of the foam material, the problem of inaccuracy in the test of the semi-rigid and soft foam materials by using the conventional rigid foam shearing test tool is solved, and the acquisition of the shearing performance of the material is more accurate;
(2) The transverse displacement compensation method of the testing device is simple and easy to operate, and has high test repeatability. Compared with the traditional rigid foam material shearing performance testing device, the whole device has the advantages that the weight of the clamp is greatly reduced, the labor intensity of testing personnel is reduced, and the testing efficiency is greatly improved;
(3) The load-deformation curve obtained by the transverse displacement compensation test method for the shearing performance of the foam material is closer to the actual deformation process of the foam material in the pure shearing stress process, and the test result has more engineering reference significance.
(4) The parallel rolling shaft between the upper guide rail and the lower guide rail of the displacement compensation mechanism can freely slide, the sliding range can be adjusted according to the thickness of a sample, the universality and the application range of the testing device are improved, and the defects of the existing foam material shearing performance testing method are effectively overcome.
Drawings
FIG. 1 is a schematic view of a transverse displacement compensation test device for the shear performance of the foam material of the present invention;
FIG. 2 is a schematic illustration of the application and curing of a foam shear sample according to the present invention;
FIG. 3 is a load-deformation curve obtained by the transverse displacement compensation test method for the shear properties of the foam material of the present invention;
FIG. 4 is a load-deformation curve obtained by a conventional tensile test method for shear mechanical properties of a foam material;
in the figure: 13-linear section of lateral displacement compensation test method, 14-linear section of traditional foam shear test method.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings.
As shown in FIG. 1, a lateral displacement compensation device for testing the shearing performance of foam comprises a force application mechanism, a metal clamping plate and a displacement compensation mechanism,
the force application mechanism comprises an upper pressure head 1, a lower pressure head 2 and a connecting mechanism 3,
the metal clamping plate comprises an upper clamping plate 6 and a lower clamping plate 7,
the displacement compensation mechanism comprises an upper guide rail 8, a lower guide rail 9 and a roller 10;
the upper pressure head 1 is of an L-shaped structure, one end of the upper pressure head is connected with a connecting rod of the connecting mechanism 3 through a locking nut 5, and the other end of the upper pressure head is connected with an upper clamping plate 6 through a fixing screw 11;
the connecting mechanism 3 comprises an upper connecting mechanism and a lower connecting mechanism, the connecting mechanisms are all composed of a connecting rod, a locking nut and a pin, and a connecting joint of the mechanical testing machine is sleeved at one end of the connecting rod and fixedly connected through the pin; the other end of the connecting rod is rigidly fixed with the pressure head through a locking nut;
the foam material test sample is adhered between an upper clamping plate 6 and a lower clamping plate 7 through an adhesive, the extension parts of the metal clamping plates are respectively and fixedly connected with an upper pressure head 1 through fixing screws 11, and the lower clamping plate 7 is fixedly connected with an upper guide rail 8 in a displacement compensation mechanism;
the lower pressure head 2 and the lower guide rail 9 are integrally designed, and at least two parallel rolling shafts 10 are arranged between the upper guide rail 8 and the lower guide rail 9;
the lower pressure head 2 is connected with a connecting rod of the lower connecting mechanism 3 through a locking nut 5, and the lower connecting rod is connected with a mechanical testing machine through a pin; the upper guide rail 8 of the displacement compensation mechanism can move along with the deformation of the foam material test sample to perform transverse compensation on the deformation.
And connecting the transverse displacement compensation test device with an electronic universal mechanical test machine. The mechanical testing machine applies longitudinal compression stress to the force applying mechanism through the connecting joint. The force application mechanism mainly comprises an upper pressure head, a lower pressure head and a connecting mechanism, wherein the upper pressure head is designed into an L-shaped structure, one end of the upper pressure head is connected with the connecting rod through a locking nut, and the other end of the upper pressure head is connected with the upper clamping plate through two M5 fixing screws; the lower pressure head and the displacement compensation mechanism are integrally designed; the connecting mechanism comprises an upper connecting mechanism and a lower connecting mechanism, and is respectively composed of a connecting rod, a locking nut and a pin, and the connecting rod is rigidly fixed with the mechanical testing machine and the pressure head through the two locking nuts.
The metal clamping plate is used for sticking a foam material shear performance test sample and consists of an upper clamping plate and a lower clamping plate. The extension parts of the metal clamping plates are respectively connected with a test device through fixing screws; the upper clamping plate is connected with the upper pressure head through two screws; the lower clamping plate is connected with the upper guide rail of the displacement compensation mechanism through two same screws. The upper and lower splints are used to measure strain with reference to the required load gauges in the GJB 130.1-86.
An upper guide rail of the displacement compensation mechanism is connected with a lower clamping plate for adhering a foam sample; the lower guide rail and the lower pressure head are integrally designed, and 4 parallel rolling shafts are arranged between the upper guide rail and the lower guide rail. The upper guide rail and the lower guide rail are of isosceles triangle structures, and the included angle between the triangle waist and the horizontal plate is 45 degrees. In the lower guide rail-lower pressure head integrated design structure, the lower pressure head is connected with a connecting rod of a lower connecting mechanism through a locking nut, so that pressure can be applied, a rolling shaft can be supported to freely roll in the horizontal direction, and the lower connecting rod is connected with a mechanical testing machine through a pin; the upper guide rail of the displacement compensation mechanism can move along with the deformation of the foam material test sample, and the purpose of transverse compensation of the deformation is achieved.
The following describes embodiments of the present invention in detail, taking as an example the method for testing the shear performance of a polyimide semi-rigid foam material for lateral displacement compensation.
(1) The foam shear test specimens were first adhered to a metal splint, followed by pressure curing. The length of the sample is 150mm, the width is 50mm, the thickness can be combined with the thickness of the material in practical application, and the recommended size is 25mm. The specific pasting process is as follows: the part of the metal splint, which is adhered with the sample, is coated with a layer of adhesive in advance, the adhesive is uniform in coating and moderate in thickness, the shearing strength needs to be higher than the shearing strength of the foam material, and after a test, the shearing failure position needs to appear at the sample part of the foam test and can not appear at the position of the adhesive film. After the glue is coated, the upper clamping plate and the lower clamping plate are oppositely arranged and staggered for a certain distance, as shown in fig. 2, a clamping plate with the same size as the upper clamping plate is added on the upper clamping plate 6 as a clamping plate, the clamping plate and the lower clamping plate 7 translate for the same distance in the opposite direction so as to achieve stress balance, and then a balancing weight 12 is added above the clamping plate so as to realize curing under fixed pressure.
After the pasting is finished, the polyimide foam is cured under certain temperature and pressure, the loading pressure of the polyimide foam cut sample is 2kPa, and the polyimide foam is cured under pressure for 24 hours under the environment of the temperature of 23 ℃ and the relative humidity (40-50)%. After the sample is cured, the upper and lower clamping plates are vertically placed on the table top, so that the sample is not stressed. When in pasting, the sample can be pasted with a plurality of foam test samples by a plurality of clamping plates;
(2) And the upper connecting rod and the lower connecting rod are respectively inserted into the connecting joint concave grooves of the mechanical testing machine and are connected with the connecting joints by pins. Go up the connecting rod and pass through pin and lock nut 4 and last attach fitting zonulae occludens, make pressure head 1 reach the rigidity fixed in the test process through rotatory lock nut 5. The locking nut 4 and the locking nut 5 of the lower connecting mechanism are screwed tightly, so that the lower connecting rod and the lower pressure head 2 are rigidly fixed respectively;
(3) Opening a mechanical testing machine for testing, hoisting the upper clamping plate 6 which is not adhered with the sample on the testing machine, and resetting the additional load brought by the testing plate; mounting the displacement compensation mechanism in place; and respectively installing the metal clamping plates adhered with the foam test samples between the upper pressure head 1 and the lower pressure head 2. Firstly, mounting a lower clamping plate 7, and then moving a mechanical testing machine to mount an upper clamping plate 6;
(4) Applying a compression stress to a foam sample at a certain loading rate, wherein the loading rate is recommended to be 1-2 mm/min, the foam material is subjected to shear deformation, the cross section of the foam material is changed from a regular rectangular structure to a parallelogram structure to generate longitudinal and transverse deformation, the transverse deformation generates a certain transverse tensile stress to the lower clamping plate 7 to drive the upper guide rail 8 and the rolling shaft 10 of the displacement compensation mechanism to horizontally move, and the transverse displacement generated by the foam in the deformation process is compensated;
(5) And repeatedly loading the polyimide foam test sample for three times, drawing a load-deformation curve, judging the range of the linear section and calculating the shear modulus. Thereafter, the loading was continued at a constant rate until breaking, resulting in the shear strength of the foam. Calculating the shear modulus of the foam material according to formula (1);
in the formula: g is the shear modulus of the sample; δ is the thickness of the sample; theta is the slope of a straight line in the load-deformation diagram; l is the original length of the sample; b is the original width of the sample.
(6) And after one test is finished, the metal clamping plate adhered with the foam material is removed, and the measurement of the next test piece is repeated or the electronic universal testing machine is closed to finish the test.
The shear performance load-deformation curve (figure 3) formed by the transverse displacement compensation test method of the shear performance of the foam material is compared with the load-deformation curve (figure 4) formed by the conventional tensile shear test method of the foam material. Using both methods, the shear modulus obtained during the repeated loading phase (second shear modulus, third shear modulus), the fourth shear modulus obtained during the continuous loading phase, and the shear strength obtained after continuous loading until failure were calculated, see table 1.
The foam lateral displacement compensation test method of fig. 3 results in a lower shear modulus than the pull-to-shear test method of fig. 4, with the shear strength of the former being slightly higher than the shear strength of the latter. The range of the linear segment 13 of fig. 3 is smaller than the range of the linear segment 14 of fig. 4 in slope, that is, within the same force value variation range, the longitudinal (i.e., tangential) deformation generated by the transverse displacement compensation test method is larger, the deformation of the foam material is closer to the real deformation, and therefore, the obtained shear modulus is smaller.
TABLE 1 shear Strength and modulus obtained by different foam shear test methods
Because the influence of transverse displacement and transverse tensile stress is reduced, the modulus tested by the shear performance transverse displacement compensation test method is smaller and is closer to the actual shear modulus. Accurate testing of the shear properties (including shear modulus and shear strength) of semi-rigid and flexible foams is realized.
Those skilled in the art will appreciate that those matters not described in detail in the present specification are well known in the art. It is to be understood that the present invention is not limited to the specific embodiments described above, and that modifications and equivalents may be made to the technical solution by those skilled in the art within the scope of the claims without affecting the spirit of the present invention.
Claims (10)
1. A transverse displacement compensation device for testing the shearing performance of foam is characterized by comprising a force application mechanism, a metal clamping plate and a displacement compensation mechanism,
the force application mechanism comprises an upper pressure head (1), a lower pressure head (2) and a connecting mechanism (3),
the metal splint comprises an upper splint (6) and a lower splint (7),
the displacement compensation mechanism comprises an upper guide rail (8), a lower guide rail (9) and a roller (10);
the upper pressure head (1) is of an L-shaped structure, one end of the upper pressure head is connected with a connecting rod of the connecting mechanism (3) through a locking nut (5), and the other end of the upper pressure head is connected with an upper clamping plate (6) through a fixing screw (11);
the connecting mechanism (3) comprises an upper connecting mechanism and a lower connecting mechanism, the connecting mechanisms are respectively composed of a connecting rod, a locking nut and a pin, and a connecting joint of the mechanical testing machine is sleeved at one end of the connecting rod and fixedly connected with the connecting rod through the pin; the other end of the connecting rod is rigidly fixed with the pressure head through a locking nut;
the foam material test sample is adhered between an upper clamping plate (6) and a lower clamping plate (7) through an adhesive, the extension part of the metal clamping plate is fixedly connected with an upper pressure head (1) through a fixing screw (11), and the lower clamping plate (7) is fixedly connected with an upper guide rail (8) in a displacement compensation mechanism;
the lower pressure head (2) and the lower guide rail (9) are integrally designed, and at least two parallel rolling shafts (10) are arranged between the upper guide rail (8) and the lower guide rail (9);
the lower pressure head (2) is connected with a connecting rod of the lower connecting mechanism (3) through a locking nut, and the lower connecting rod is connected with a mechanical testing machine through a pin; the upper guide rail (8) of the displacement compensation mechanism can move along with the deformation of the foam material test sample to perform transverse compensation on the deformation.
2. The lateral displacement compensation device for testing the shearing performance of the foam as claimed in claim 1, wherein the cross sections of the upper guide rail (8) and the lower guide rail (9) are both isosceles triangle structures, and the included angle between the triangle waist and the horizontal plate is 45 degrees.
3. The lateral displacement compensation device for testing the shear performance of foam according to claim 1, wherein the shear modulus of the foam is determined by:
in the formula: g is the shear modulus of the sample; δ is the thickness of the sample; theta is the slope of a straight line in the load-deformation diagram; l is the original length of the sample; b is the original width of the sample.
4. The lateral displacement compensation device for testing the shear performance of foam according to claim 1, wherein the foam test sample is adhered between the upper clamping plate (6) and the lower clamping plate (7) by the adhesive by the following method: coating a layer of adhesive on the part of the metal splint, which is adhered with the sample, in advance to ensure that the foam sample is respectively adhered close to the upper edge and the lower edge of the two splints, and oppositely placing the upper splint (6) and the lower splint (7) and staggering a certain distance after the adhesive is coated; after the sample is cured, the upper clamping plate and the lower clamping plate are vertically placed on a table top to prevent the sample from being subjected to any pressure.
5. A lateral displacement compensation method for testing the shear performance of foam, which is characterized by using the lateral displacement compensation device of claims 1-4, comprising the following steps:
the method comprises the following steps that firstly, an upper connecting rod and a lower connecting rod are respectively inserted into a connecting joint concave groove of a mechanical testing machine to be connected, one end of the upper connecting rod is fixedly connected with an upper connecting joint, the other end of the upper connecting rod is fixedly connected with an upper pressure head (1), and the upper connecting rod and the upper pressure head are rigidly fixed in the testing process through rotating a locking nut (4) and a locking nut (5); the lower connecting mechanism enables the lower connecting rod and the lower pressure head (2) to respectively achieve rigid fixed connection through a locking nut;
opening a mechanical testing machine, hoisting an upper clamping plate (6) which is not adhered with a sample on the testing machine, and resetting the additional load brought by the testing plate; mounting the displacement compensation mechanism in place; respectively arranging metal clamping plates adhered with foam test samples between an upper pressure head (1) and a lower pressure head (2);
thirdly, applying a pressing shear stress to the foam test sample at a certain loading rate, namely applying a downward pressure to the upper clamping plate (6) and applying an upward pressure to the lower clamping plate (7), wherein the foam material generates longitudinal and transverse deformation under the action of the shear stress, and the lower clamping plate (7) drives the displacement compensation mechanism to horizontally move under the action of the transverse tensile stress to compensate the transverse displacement;
and step four, repeatedly loading the foam sample at a certain loading rate for three times, drawing a load-deformation curve, calculating the shear modulus in a linear section range, and continuously loading at a constant rate until the foam sample is broken to obtain the shear strength of the foam material.
6. The lateral displacement compensation method for testing the shearing performance of the foam as claimed in claim 5, wherein the method for adhering the sample on the metal clamping plate comprises the following steps:
coating a layer of adhesive on the part, which is adhered with the sample, of the metal clamping plate in advance, so that the foam sample is respectively adhered close to the upper edge and the lower edge of the two clamping plates, and after the adhesive is coated, oppositely placing the upper clamping plate (6) and the lower clamping plate (7) and staggering a certain distance; after the pasting is finished, a clamping plate with the same size as the upper clamping plate is added on the upper clamping plate (6) to serve as a pressing plate, the upper clamping plate and the lower clamping plate (7) move horizontally for the same distance in the opposite direction to achieve stress balance, then a balancing weight (12) is added above the pressing plate, pressurization curing is carried out for at least 24 hours under the condition of normal temperature, and after sample curing is finished, the upper clamping plate and the lower clamping plate are vertically placed on a table top to be free of any pressure.
7. The lateral displacement compensation method for testing the shearing performance of the foam is characterized in that the displacement compensation mechanism comprises an upper guide rail (8), a lower guide rail (9) and a roller (10); the lower clamping plate (7) is fixedly connected with an upper guide rail (8) in the displacement compensation mechanism;
the lower pressure head (2) and the lower guide rail (9) are integrally designed, and at least two parallel rolling shafts (10) are arranged between the upper guide rail (8) and the lower guide rail (9);
the upper guide rail (8) of the displacement compensation mechanism can move along with the deformation of the foam material test sample to perform transverse compensation on the deformation.
8. The lateral displacement compensation method for testing the shearing performance of the foam as claimed in claim 7, wherein the sections of the upper guide rail (8) and the lower guide rail (9) are both isosceles triangle structures, and the included angle between the triangle waist and the horizontal plate is 45 °.
9. The method for compensating lateral displacement for testing the shear performance of foam according to claim 5, wherein the shear modulus of the foam material is determined by:
in the formula: g is the shear modulus of the sample; δ is the thickness of the sample; theta is the slope of a straight line in the load-deformation diagram; l is the original length of the sample; b is the original width of the sample.
10. The method of claim 5, wherein the foam test sample is applied with a compressive shear stress at a loading rate of 1-3mm/min in step three, and the foam sample is repeatedly loaded at a loading rate of 1-3mm/min three times and continuously loaded at a constant rate of 3-5mm/min until the foam sample breaks in step four.
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| CN112666008A (en) * | 2020-11-26 | 2021-04-16 | 山东云海国创云计算装备产业创新中心有限公司 | SoC packaging interconnection structure shearing reliability equivalent test device and method |
| CN113029942B (en) * | 2021-03-12 | 2022-03-15 | 上海交通大学 | Single-interface bonding strength evaluation test method |
| CN113484164A (en) * | 2021-07-30 | 2021-10-08 | 中国航空工业集团公司济南特种结构研究所 | Tool and method for testing shear strength of sealant |
| CN113484165B (en) * | 2021-07-30 | 2024-04-09 | 中国航空工业集团公司济南特种结构研究所 | Efficient test method for shearing mechanical property of composite material |
| CN114986419B (en) * | 2022-07-15 | 2023-07-14 | 国网甘肃省电力公司电力科学研究院 | Auxiliary fixing device for plating thickness measurement sample |
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| CN102252786B (en) * | 2011-06-13 | 2013-04-03 | 宾伟雄 | Shear force testing device |
| CN202886198U (en) * | 2012-10-15 | 2013-04-17 | 同济大学 | Special device for foam material shearing elasticity performance measurement |
| DE112012007218B4 (en) * | 2012-12-12 | 2018-04-05 | Ima Materialforschung Und Anwendungstechnik Gmbh | Shear test device for mechanical material testing |
| DE102015003689A1 (en) * | 2015-03-24 | 2016-09-29 | Karlsruher Institut für Technologie | Apparatus and method for determining the shear strength and shear modulus of composites |
| CN111272583B (en) * | 2020-03-31 | 2023-05-23 | 河南牛帕力学工程研究院 | Pressure shear testing machine |
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