JP5458473B2 - Stress measuring apparatus and stress measuring method using the same - Google Patents

Description

  The present invention relates to a stress measuring apparatus for measuring stress, particularly compressive stress, and a stress measuring method using the same.

  In an undercarriage member such as an automobile, measurement of stress by attaching a strain gauge is known (for example, see Non-Patent Document 1).

Usually, the strain gauge can be affixed to any part of the member. However, it is empirically known that when a strain gauge is attached to a site where compressive stress is generated, the reproducibility of the measured stress is low. For this reason, generally, a strain gauge is attached by forming a notch or the like at a site where tensile stress is generated.
“SAE Paper”, no. 940333, 1994

  However, if a notch or the like is formed at a site where tensile stress occurs, there is a problem that the strength of the member is greatly reduced.

  Further, the shape of the member is generally complicated, and the deformation of the member when a force is applied to the member is not uniform. For this reason, when a strain gauge is directly attached to a member having a complicated shape, there is a problem that the reproducibility of the measured stress is low.

  The present invention has been made to solve the problems associated with the above-described prior art, and provides a stress measuring apparatus and a stress measuring method capable of measuring the stress with high reproducibility while maintaining the strength reliability of the member to be measured. The purpose is to do.

In order to achieve the above object, the invention described in claim 1
When a force is applied to the member to be measured, leg portions attached to the compression portion of the member to be measured that generate a compressive stress according to the force and paired apart from each other;
A plate-like strain generating portion disposed between the leg portions;
A mechanical quantity sensor provided on the plane of the strain generating part,
The strain generating portion is made of a magnetic material,
The mechanical quantity sensor is a magnetostrictive sensor having a magnet and a magnetic sensor arranged on the opposite side via the strain generating portion,
The magnetizing direction of the magnet is substantially orthogonal to the direction of stress acting on the strain-generating portion,
In the stress measuring device, the thickness of both end portions in the cross-sectional shape intersecting with the separation direction of the leg portion of the strain generating portion is thicker than that of the central portion.

In order to achieve the above object, the invention described in claim 8 provides:
When a force is applied to the member to be measured, a compressive stress is generated according to the force.
A pair of legs that are spaced apart to be attached to the compression part, disposed between the legs, the thickness of both ends in the cross-sectional shape intersecting the separation direction of the legs is thicker than the center part, A plate-like strain generating portion made of a magnetic material, a magnet that is arranged on a plane of the strain generating portion and whose magnetization direction is substantially perpendicular to the direction of stress acting on the strain generating portion, and the magnet via the strain generating portion Is a stress measuring method in which a stress measuring device having a magnetic sensor arranged on the opposite side of the sensor is attached and the compressive stress is measured.

  According to invention of Claim 1, a leg part is attached to the compression part of the to-be-measured member which a compressive stress produces. The compression portion has a smaller strength drop when a notch or the like is formed than a portion where tensile stress occurs. For this reason, when a leg part is attached to a member to be measured, strength reduction of a member can be controlled.

  In the first aspect of the present invention, the mechanical quantity sensor is attached to the strain generating portion disposed between the separated leg portions. For this reason, the average compressive stress of the member between the spaced apart leg portions can be measured, and variations in the measured compressive stress can be suppressed.

  Therefore, it is possible to provide a stress measuring device that can maintain the strength reliability of the member to be measured and can measure stress with high reproducibility.

  According to the ninth aspect of the present invention, the stress measuring device is attached to the compressed portion where the compressive stress is generated. The compression portion has a smaller strength drop when a notch or the like is formed than a portion where tensile stress occurs. For this reason, when a stress measuring device is attached to a member to be measured, strength reduction of the member can be suppressed.

  According to the ninth aspect of the present invention, the mechanical quantity sensor is provided in the strain generating portion disposed between the separated leg portions, and the average compressive stress of the member between the leg portions is measured. For this reason, the dispersion | variation in the compressive stress measured can be suppressed.

  Therefore, it is possible to provide a stress measurement method capable of measuring the stress with high reproducibility while maintaining the strength reliability of the member to be measured.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 is a perspective view showing a stress measuring device, FIG. 2 is a sectional view taken along line II-II in FIG. 1, FIG. 3 is a sectional view taken along line III-III in FIG. 1, and FIG. FIG. 5 is a cross-sectional view taken along line VV in FIG. 4, FIGS. 6 and 7 are stress contour diagrams showing stress analysis results, and FIG. 8 is a graph showing sensitivity and sensor characteristics of the stress measuring device. It is.

  Referring to FIGS. 1 and 2, stress measuring apparatus 10 includes leg portions 16A and 16B that are spaced apart from each other, plate-like strain generating portion 11 that is disposed between legs 16A and 16B, And a mechanical quantity sensor provided on the planes 17A and 17B of the strain portion 11. The mechanical quantity sensor according to the embodiment is a magnetostrictive sensor 19.

  The strain generating portion 11 is a substantially rectangular plate shape with a thick peripheral edge 13 and is formed integrally with the leg portions 16A and 16B at both ends in the longitudinal direction. The strain generating portion 11 and the leg portions 16A and 16B are made of a magnetostrictive material. The magnetostrictive material is, for example, maraging steel or FeCoV alloy.

  The leg portions 16A and 16B are attached to the compression portion of the member to be measured in which compressive stress is generated according to the force applied to the member to be measured so that the separation direction of the leg portions 16A and 16B and the main stress direction coincide with each other. In addition, leg part 16A, 16B can also be attached to a compression part by shifting the main stress direction and the separation direction of leg part 16A, 16B. The leg portions 16A and 16B and the member to be measured are joined by electron beam welding. TIG, MIG, high energy beams such as plasma and laser, friction welding, or resistance welding can be applied to join the legs 16A and 16B to the member to be measured.

  Hereinafter, in the stress measuring apparatus 10, the side located in the direction in which the leg portions 16A, 16B extend is referred to as the back side of each member, and the side located in the direction opposite to the direction in which the leg portions 16A, 16B extend is referred to as each member. The front side.

  In the magnetostrictive sensor 19, the magnet 14 and the magnetic sensor 15 are arranged via the strain generating portion 11. Specifically, the magnet 14 is disposed on the front surface 17A of the flat plate-like portion 12 of the strain-generating portion 11, and the magnetic sensor 15 is disposed on the back surface 17B of the flat plate-like portion 12. The magnetic sensor 15 is, for example, a linear Hall IC.

  The magnetization direction of the magnet 14 is perpendicular to the plane of the strain generating portion 11. That is, the magnetizing direction of the magnet 14 is perpendicular to the front surface 17A and the back surface 17B of the flat plate-like portion 12. When no force is applied to the strain generating portion 11, the magnetization in the strain generating portion 11 is constrained by the magnetic field of the magnet 14. When a compressive force is applied to the strain-generating part 11 from the separation direction of the legs 16A and 16B, magnetization perpendicular to the front surface 17A and the back surface 17B increases. Therefore, the leakage magnetic flux increases. On the contrary, when the strain generating portion 11 is pulled in the separation direction of the leg portions 16A and 16B, the magnetization parallel to the front surface 17A and the back surface 17B increases, and the leakage magnetic flux decreases. Therefore, the stress can be measured by detecting a change in leakage magnetic flux.

  The magnet 14 is covered with a first yoke 20 formed of the same magnetostrictive material as the strain-generating portion 11 and the leg portions 16A and 16B. The first yoke 20 includes first yoke legs 22 and 23 and a plate-like flat portion 21. The thickness of the flat portion 21 is substantially equal to the thickness of the flat plate-like portion 12 of the strain-generating portion 11. The flat portion 21 has a substantially rectangular shape, and first yoke leg portions 22 and 23 are formed at both ends of the flat portion 21 in the longitudinal direction. The first yoke legs 22 and 23 are attached to the surface 17 </ b> A of the flat plate-like portion 12 so as not to cause stress in the flat portion 21. The magnet 14 is disposed between the first yoke legs 22 and 23, and resin is molded between the first yoke legs 22 and 23.

  Covering the magnet 14 with the first yoke 20 is equivalent to increasing the permeance of the magnet 14. Therefore, the magnet 14 can be stabilized. For this reason, the thin magnet 14 can be used and the stress measuring apparatus 10 can be reduced in size.

  A dummy sensor 25 is disposed on the front side of the flat portion 21 of the first yoke 20. The dummy sensor 25 is the same sensor as the magnetic sensor 15 and is, for example, a linear Hall IC. The magnetic sensor 15 and the dummy sensor 25 are disposed at substantially the same position from the magnet 14. Further, as described above, since the flat plate portion 12 of the strain generating portion 11 and the flat portion 21 of the first yoke 20 are made of the same material and have substantially the same thickness, a force is applied to the strain generating portion 11. When not, the magnetic flux leakage in the magnetic sensor 15 and the dummy sensor 25 is substantially the same.

  The first yoke 20 is attached to the strain-generating portion 11 so that the first yoke legs 22 and 23 do not cause stress in the flat portion 21. When force is applied to the strain-generating portion 11, the influence of the stress is directly applied. I do not receive it. Therefore, the dummy sensor 25 can monitor the magnetic flux that varies depending on the temperature that is hardly affected by the stress. For this reason, the temperature characteristics of the output of the stress measuring device 10 can be improved by making the magnetic sensor 15 and the dummy sensor 25 differential.

  The magnetic sensor 15 is covered with a tunnel-like second yoke 26. Similarly, the dummy sensor 25 is also covered with a tunnel-like third yoke 27. Thus, the magnetic flux collecting effect can be obtained by covering the magnetic sensor 15 and the dummy sensor 25 with the yoke. Therefore, the sensitivity of the magnetic sensor 15 and the dummy sensor 25 can be increased approximately twice. Moreover, the influence on the magnetic sensor 15 and the dummy sensor 25 by the magnetic field from the outside can be suppressed.

  Referring to FIG. 3, the stress measuring apparatus 10 has a thick peripheral edge 13 of the strain-generating portion 11, and a cross section of the strain-generating portion 11 in a plane perpendicular to the separation direction of the leg portions 16 </ b> A and 16 </ b> B is H Has a shape. For this reason, when compressive stress is applied from the separation direction of the leg portions 16A and 16B, the strain-generating portion 11 becomes difficult to buckle, and the range of measurable stress can be expanded.

  The magnetic sensor 15 and the dummy sensor 25 are held by resin molded in the cavity of the yoke. Pins 18 and 28 for connecting each sensor and an external signal line are taken out from the molded resin.

  As described above, in the stress measuring device 10 according to the embodiment, the leg portions 16A and 16B are attached to the compression portion that receives compressive stress. The compression portion has a smaller strength drop when a notch or the like is formed than a portion where tensile stress occurs. For this reason, when the leg portions 16A and 16B are attached to the member to be measured, a reduction in strength of the member can be suppressed.

  In the stress measuring device 10 according to the embodiment, the magnetostrictive sensor 19 is provided in the strain generating portion 11 disposed between the separated leg portions 16A and 16B. For this reason, the average compression amount of the member between the leg portions 16A and 16B can be measured, and variations in the measured compressive stress can be suppressed.

  Therefore, the stress measuring device 10 according to the embodiment can measure the stress with high reproducibility while maintaining the strength reliability of the member to be measured.

  Next, a stress measurement method will be described. In addition, the same code | symbol is attached | subjected to the member which is common in the member shown to FIGS.

  First, a member to be measured which is a stress measurement target will be described.

  With reference to FIG. 4, the member to be measured according to the embodiment is a caliper support 30 that is an underbody part of an automobile. The caliper support 30 supports the two pads 40 and 50 that are stationary by sandwiching the rotating disk rotor 60. The disk rotor 60 is a disk-shaped member that rotates together with the wheels.

  The pads 40 and 50 are substantially rectangular plate materials having friction materials 44 and 54 on the side facing the disk rotor 60, and have convex portions 41, 42, 51 and 52 at both ends in the longitudinal direction. Hereinafter, in the pads 40 and 50, the surface opposite to the surface on which the friction materials 44 and 54 are provided is referred to as the pressing surfaces 43 and 53.

  The two pads 40 and 50 are supported by a first pad support member 31 and a second pad support member 32 provided on the caliper support 30, respectively.

  The first pad support member 31 and the second pad support member 32 have front support portions 31A and 32A and rear support portions 31B and 32B, which are disposed in the longitudinal direction of the pads 40 and 50, respectively. The disk rotor 60 rotates from the rear support part side to the front support part side. The front support portion 31A and the rear support portion 31B of the first pad support member 31 are connected by a substantially U-shaped connection portion 31C. On the other hand, the front support portion 32A and the rear support portion 32B of the second pad support member 32 are integrally formed and have a substantially U shape.

  In the first pad support member 31 and the second pad support member 32, the front support portions 31A and 32A are formed integrally with the front connection member 36A, and the rear support portions 31B and 32B are formed integrally with the rear connection member 36B. Yes.

  The front support portion 31A and the rear support portion 31B of the first pad support member 31, and the front support portion 32A and the rear support portion 32B of the second pad support member 32 are recessed portions 33A, 33B, which are grooves having a substantially rectangular cross section. 34A and 34B.

  The concave portions 33A, 33B, 34A, 34B are formed at positions facing the convex portions 41, 42, 51, 52 provided at both ends of the pads 40, 50, respectively. The first pad support member 31 and the second pad support member 32 have the convex portions 41, 42, 51, 52 of the pads 40, 50 as the concave portions 33A, 33B, 34A of the front support portions 31A, 32A and the rear support portions 31B, 32B. , 34B, the pads 40, 50 are slidably supported.

  A caliper (not shown) is attached to the caliper support 30. The caliper includes a cylinder filled with brake oil. A piston is provided in the cylinder, and the piston slides due to a brake operating pressure applied to the brake oil. When the brake is applied, the piston presses the pressing surfaces 43 and 53 of the pads 40 and 50. The two pressed pads 40 and 50 slide, and the friction members 44 and 54 are pressed against the plane of the disk rotor 60. The disk rotor 60 stops rotating due to friction between the friction members 44 and 54 and the disk rotor 60.

  Referring to FIG. 5, when the friction members 44 and 54 are pressed against the rotating disk rotor 60, the pads 40 and 50 cause the disk rotor 60 to move due to the friction generated between the friction members 44 and 54 and the disk rotor 60. Move in the direction of rotation. By moving the pads 40 and 50 in this way, one of the convex portions 41 and 51 of the pads 40 and 50 is pressed against the concave portions 33A and 34A of the front support portion. On the other hand, the other convex portions 42 and 52 of the pads 40 and 50 are separated from the concave portions 33B and 34B of the rear support portions 31B and 32B.

  The analysis results of the stress received by the front support portion 32A and the rear support portion 32B of the second pad support member 32 at this time are shown in FIGS. 6 is a stress distribution (minimum principal stress) on the front surface 37A located on the opposite side of the surface on which the convex portions 41 and 51 abut, and FIG. 7 is located on the opposite side of the surface on which the convex portion 52 is separated. It is the stress distribution (minimum principal stress) in the back surface 37B. Each line shown in FIG. 6 and FIG. 7 is an iso-stress line connecting portions having the same stress value.

  The stress value at each isostress line is negative. Therefore, during the braking operation, the front surface 37A of the front support portion 32A receives compressive stress. In particular, the front surface 37A of the front support portion 32A is subjected to a large compressive stress as the stress value decreases toward the center of the member with reference to FIG.

  The stress measuring method according to the embodiment will be described using the caliper support 30 as described above as a member to be measured.

  In the stress measurement method, legs 16A, 16B, legs 16A, 16A, 16A, 16A, 16A, 16A, 16A, 16A, 16A, 16A, 16A, 16A, 16A, 16A, 16A, 16A, 16A, 16A The stress measuring device 10 having a plate-like strain generating portion 11 disposed between 16B and a mechanical quantity sensor provided on the plane of the strain generating portion 11 is separated from the main stress direction of the compressive stress and the legs 16A and 16B. It is a method of measuring the compressive stress by attaching the same direction.

  More specifically, in the embodiment, the member to be measured is the caliper support 30, and the compression portion of the member to be measured is the front surface 37A of the front support portion 32A.

  In the second pad support member 32, a notch 38 having a substantially rectangular cross section is formed on the front surface 37 </ b> A of the front support portion 32 </ b> A, and the leg portions 16 </ b> A and 16 </ b> B of the stress measuring device 10 are attached to the flat surface 39 of the notch 38. . At this time, the separation direction of the leg portions 16A and 16B and the main stress direction of the front support portion 32A are matched. The leg portions 16A and 16B can be attached to the flat surface 39 by shifting the main stress direction and the separating direction of the leg portions 16A and 16B.

  When the pad 50 comes into contact with the front support portion 32A and the front surface 37A receives compressive stress, the strain-generating portion 11 of the stress measuring device 10 receives compressive stress from the separation direction of the leg portions 16A and 16B. For this reason, the magnetization perpendicular to the front surface 17A and the back surface 17B of the plate-like portion 12 of the strain-generating portion 11 increases, and the leakage magnetic flux increases. Therefore, the compressive stress can be measured based on the change in magnetic flux detected by the magnetic sensor 15.

  The compressive stress is generated according to the force applied from the pads 40 and 50 when the disk rotor 60 which is a moving member combined with the caliper support 30 is braked. For this reason, a braking force can be calculated | required and it can contribute to realization of vehicle behavior control by attaching the stress measuring device 10 to the caliper support 30. FIG.

  As described above, the stress measurement method according to the embodiment measures stress in the compressed portion of the caliper support 30 that receives compressive stress. The compression portion has a smaller strength drop when a notch or the like is formed than a portion where tensile stress occurs. For this reason, the strength reduction of the caliper support 30 can be suppressed during the stress measurement. Therefore, the stress measurement method according to the embodiment can maintain the strength reliability of the member.

  Further, since the measurement is performed at the compression section, a high magnetostrictive material having a low tensile strength can be employed for the magnetostrictive sensor.

  As shown in FIG. 6, the stress distribution generated when a force is applied to the caliper support 30 is not uniform. However, in the stress measurement method of the present embodiment, the magnetostrictive sensor 19 is provided in the strain-generating portion 11 disposed between the separated leg portions, and the average compressive stress between the leg portions is measured. For this reason, the dispersion | variation in the compressive stress measured can be suppressed. Therefore, the stress measurement method according to the embodiment can measure stress with high reproducibility.

  Next, examples will be described.

<Example 1>
The leg portions 16A and 16B and the strain generating portion 11 of the stress measuring device 10 were formed by machining maraging steel. As maraging steel, YAG300 (18% Ni-9% Co-5% Mo) manufactured by Hitachi Metals was used. The thickness of the flat plate-like portion 12 of the strain generating portion 11 was 0.5 mm, and the thickness of the peripheral edge 13 of the strain generating portion 11 was 1.5 mm. The width of the strain generating portion 11 is 10 mm. Further, the first yoke leg portions 22 and 23 and the flat portion 21 were also formed by machining maraging steel, and the thickness of the flat portion 21 was 0.5 mm.

  After the machining, the leg portions 16A and 16B, the strain generating portion 11 and the first yoke 20 were subjected to solution treatment and aging heat treatment. Solid solution conditions are cooling to 100 degrees C or less after hold | maintaining at 820 degreeC in a vacuum for 1 hour. The aging conditions are a vacuum at 490 ° C. for 5 hours, and then air cooling.

  As the magnet 14, a samarium cobalt (SmCo) magnet having a diameter of 3 mm and a length of 3.5 mm was used. The SmCo magnet is magnetized at 10T, and then heat-treated at 200 ° C. for 1 hour. The magnetic flux density at the end face of the magnet 14 alone is about 4.1 kG.

  The second yoke 26 and the third yoke 27 were formed by machining PB (Ni—Fe) permalloy (soft magnetic material). After the machining, heat treatment was performed in pure hydrogen at 1200 ° C. for 2 hours.

  Linear Hall ICs were used for the magnetic sensor 15 and the dummy sensor 25. The magnetic sensitivity was about 7 mV / G.

  The stress measuring device 10 was attached to the caliper support 30 by joining the legs 16A and 16B to the flat surface 39 of the notch 38 formed in the caliper support 30. The caliper support 30 was formed from an FCD material (spheroidal graphitized cast iron). The joining of the legs 16A and 16B and the caliper support 30 is electron beam welding.

  FIG. 8 shows the sensitivity and sensor characteristics of the stress measuring device 10 manufactured as described above. The vertical axis represents the sensor output ΔB [G]. The horizontal axis represents the load [kN] applied to the recess 34A of the front support portion 32A in the second pad support member 32 in the direction from the rear support portion 32B toward the front support portion 32A.

  As clearly shown in FIG. 8, the stress measuring device 10 has a good sensitivity, and its sensor characteristics are linear without hysteresis. That is, the stress measuring apparatus 10 can detect stress with high reproducibility. Also, the temperature characteristics were good in the range of -30 ° C to 100 ° C.

<Example 2>
In the stress measuring device 10 of Example 1, the leg portions 16A and 16B, the strain generating portion 11 and the first yoke 20 were formed of permendur (Fe49Co49V2 alloy). The leg portions 16A and 16B, the strain generating portion 11 and the first yoke 20 were subjected to heat treatment. The heat treatment was performed in pure hydrogen at 840 ° C. for 2 hours, and then cooled in a furnace at 100 ° C./hr to 400 ° C. or lower.

  As a result of performing the same test as in Example 1, the sensitivity was improved about twice as much as that in Example 1. The sensor characteristic was linear without hysteresis.

<Example 3>
The strain generating part 11 and the leg parts 16A and 16B were formed by machining SUS. A strain gauge was bonded to the strain generating portion 11 with an adhesive.

  As a result of performing the same test as in Example 1, the sensor characteristics were linear without hysteresis. Therefore, even if a strain gauge is used as the mechanical quantity sensor, the stress can be detected with good reproducibility.

<Example 4>
In the third embodiment, a semiconductor strain sensor is used instead of the strain gauge. The semiconductor strain sensor and the strain generating portion 11 were joined with an adhesive.

  When the test similar to Example 1 was implemented, the result similar to the stress measuring apparatus 10 of Example 3 was able to be obtained. Therefore, even if a semiconductor strain sensor is used as the mechanical quantity sensor, the stress can be detected with good reproducibility.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims.

  For example, in the above-described embodiment, the linear Hall IC is described as the magnetic sensor 15 and the dummy sensor 25. For example, a Hall element or a GMR (Giant Magneto Resistance Effect) sensor is applied from the viewpoint of power saving and downsizing. It is also possible to do.

  Further, the material for forming the strain generating portion 11 is not limited to maraging steel or FeCoV alloy, and FeAl alloy (for example, Alfel), FeGa alloy, and FeGaAl alloy (for example, galphenol) having a good magnetostrictive effect are applied. It is also possible to do.

  Furthermore, it is also possible to apply a semiconductor stress sensor using MEMS (Micro Electro Mechanical Systems) as a mechanical quantity sensor.

It is a perspective view which shows a stress measuring device. It is sectional drawing which follows the II-II line | wire of FIG. It is sectional drawing which follows the III-III line of FIG. It is a perspective view which shows the stress measuring device attached to the caliper. It is sectional drawing which follows the VV line of FIG. It is an elastic stress analysis result in the front support part front surface of a 2nd pad support member. It is an elastic stress analysis result in the back support part back of the 2nd pad support member. It is a graph which shows the sensitivity and sensor characteristic of a stress measuring device.

Explanation of symbols

10 Stress measuring device,
11 strain generating part,
13 Perimeter,
14 magnets,
15 magnetic sensor,
16A, 16B legs,
18, 28 pins,
19 magnetostrictive sensor,
20 first yoke,
25 Dummy sensor,
26 Second yoke,
27 Third yoke.

Claims (14)

When a force is applied to the member to be measured, leg portions attached to the compression portion of the member to be measured that generate a compressive stress according to the force and paired apart from each other;
A plate-like strain generating portion disposed between the leg portions;
A mechanical quantity sensor provided on the plane of the strain generating part,
The strain generating portion is made of a magnetic material,
The mechanical quantity sensor is a magnetostrictive sensor having a magnet and a magnetic sensor arranged on the opposite side via the strain generating portion,
The magnetizing direction of the magnet is substantially orthogonal to the direction of stress acting on the strain-generating portion,
The stress measuring device in which the thickness of both end portions in the cross-sectional shape intersecting with the separation direction of the leg portion of the strain generating portion is thicker than that of the central portion.   The stress measuring device according to claim 1, wherein the leg portions are separated in a main stress direction of the compressive stress.   The stress measuring device according to claim 1, wherein the member to be measured has a flat surface formed on the compression portion, and the leg portion is attached to the flat surface of the compression portion. The stress measuring device according to any one of claims 1 to 3, wherein the strain generating portion is maraging steel, FeCoV alloy, FeAl alloy, FeGa alloy, or FeGaAl alloy . Stress measuring apparatus according to any one of claims 1 to 4, characterized in that the periphery of the strain element is a thick-walled. The force, the stress measuring device according to any one of claims 1 to 5, characterized in that applied at the time of braking of the movement member in combination with the measured member. The stress measuring device according to claim 1 , wherein the member to be measured is a caliper support . When a force is applied to the member to be measured, a compressive stress is generated according to the force.
A pair of legs that are spaced apart to be attached to the compression part, disposed between the legs, the thickness of both ends in the cross-sectional shape intersecting the separation direction of the legs is thicker than the center part, A plate-like strain generating portion made of a magnetic material, a magnet that is arranged on a plane of the strain generating portion and whose magnetization direction is substantially perpendicular to the direction of stress acting on the strain generating portion, and the magnet via the strain generating portion A stress measuring method for measuring the compressive stress by attaching a stress measuring device having a magnetic sensor disposed on the opposite side of the magnetic sensor . The stress measurement method according to claim 8, wherein the leg portions are separated in a main stress direction of the compressive stress . The stress measuring method according to claim 8 or 9, wherein the member to be measured has a flat surface formed on the compression portion, and the leg portion is attached to the flat surface of the compression portion . The stress measuring method according to any one of claims 8 to 10, wherein the strain-generating portion is maraging steel, FeCoV alloy, FeAl alloy, FeGa alloy, or FeGaAl alloy . The stress measuring method according to any one of claims 8 to 11, wherein a peripheral edge of the strain generating portion is thick . The stress measurement method according to claim 8 , wherein the force is applied during braking of a moving member combined with the member to be measured. The stress measurement method according to any one of claims 8 to 13 , wherein the member to be measured is a caliper support .

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