JP6003479B2 - Biaxial four-point bending test equipment - Google Patents

Description

  The present invention relates to a biaxial four-point bending test apparatus.

  2. Description of the Related Art Conventionally, a test piece bending test apparatus has two support points fixed at positions spaced apart in the horizontal direction, and one side (lower surface side) of the test piece is supported by the support points. Bending stress is applied to the test piece from the other side (upper side) of the test piece by pressing one loading point in the case of three-point bending and two loading points in the case of four-point bending. (For example, refer to Patent Document 1).

  Further, as a four-point bending test apparatus that allows fatigue strength to be measured by repeatedly applying positive and negative bending stresses to a test piece, for example, there is one disclosed in Patent Document 2.

  The four-point bending test apparatus disclosed in Patent Document 2 has a center jig and side jigs located on both sides of the center jig, and each side jig has a lower support by a roller. The center jig is provided at a position where the lower loading point and the upper loading point by a roller arranged at a predetermined interval in the horizontal direction coincide with each other in the vertical direction. A test piece is arranged between the lower support point and the upper support point of the tool and between the lower load point and the upper load point of the center jig.

  Then, by moving the center jig with the side jigs arranged on both sides up and down, positive and negative bending is alternately applied to the test piece by the lower loading point and the upper loading point of the center jig. The load from the compressive stress to the tensile stress can be repeatedly applied to one side and the other side of the test piece.

Japanese Patent Laid-Open No. 5-322728 JP 2000-131206 A

  By the way, in the conventional four-point bending test apparatus as disclosed in Patent Documents 1 and 2, with respect to a single axis extending in a direction penetrating horizontally through the central portion of the test piece, the vertical direction is provided on the left and right sides thereof. The fatigue strength data of the test piece is acquired by so-called uniaxial loading in which a load is applied to the test piece.

  However, in an actual machine, it is very rare that only a uniform stress due to the uniaxial loading is generated in a part or the like. Therefore, the fatigue strength data of a test piece acquired by a conventional four-point bending test apparatus is the test piece. The actual fatigue strength of the material was different, and the accuracy of the material soundness evaluation was reduced.

  In view of such circumstances, the present invention provides a biaxial four-point bending test apparatus that can measure the actual fatigue strength of a test piece by simulating a loading state close to an actual machine, and can improve the accuracy of material soundness evaluation. It is something to be offered.

The present invention provides four support points on one side of a flat test piece, a first axis extending in one direction within the plane of the test piece, and a second axis extending in a direction intersecting the first axis. And four loading points on the other surface side of the test piece, spaced apart from each other in the first axial direction and the second axial direction,
The test point is arranged such that the load points described above are disposed within the separation interval of the support points in the first axial direction, and the support points are disposed within the separation interval of the loading points in the second axial direction. Configure to generate a stress field where tensile stress and compressive stress intersect at the center of the piece ,
The first axis and the second axis are X and Y axes extending in directions orthogonal to each other, the support point and the loading point are arranged symmetrically with respect to the X axis as a reference line, and the Y axis is set as a reference line As described above, the support point and the loading point are arranged symmetrically about a biaxial four-point bending test apparatus.

  According to the above means, the following operation can be obtained.

  When a bending test is performed by placing a support point and a loading point as described above and applying a predetermined load by a testing machine, a stress field where tensile stress and compressive stress intersect is formed at the center of the test piece. Can be generated.

  As a result, in the conventional four-point bending test apparatus as disclosed in Patent Documents 1 and 2, with respect to one axis extending in a direction penetrating horizontally through the central portion of the test piece, it is The fatigue strength data of the test piece can only be obtained by so-called uniaxial loading in which a load is applied in the direction, but the fatigue strength data of the test piece obtained in the present invention is uniform by the uniaxial loading. Therefore, the accuracy of the soundness evaluation of the material is greatly improved.

  The first axis and the second axis are X and Y axes extending in directions orthogonal to each other, the support point and the loading point are arranged symmetrically with respect to the X axis as a reference line, and the Y axis is set as a reference line In the biaxial four-point bending test apparatus in which the support point and the loading point are arranged in line symmetry, the arrangement of the support point and loading point in the biaxial four-point bending test apparatus is set as a reference arrangement, with the X axis being sandwiched oppositely. The two loading points are arranged at positions where each loading point is moved in the X-axis direction so that two straight lines connecting the loading points of each set are inclined at an angle other than 90 ° with respect to the X-axis. You can also

  The first axis and the second axis are X and Y axes extending in directions orthogonal to each other, the support point and the loading point are arranged symmetrically with respect to the X axis as a reference line, and the Y axis is set as a reference line As a reference arrangement of the support point and the loading point in the biaxial four-point bending test apparatus in which the support point and the loading point are arranged in line symmetry, the intersection of the X axis and the Y axis is used as a reference. A point-symmetrical positional relationship with respect to the intersection of the X-axis and the Y-axis is maintained for each of the two loading points of one set among the two loading points arranged at point-symmetrical positions as points. As described above, it may be arranged at a position moved in the Y-axis direction.

  The first axis and the second axis are X and Y axes extending in directions orthogonal to each other, the support point and the loading point are arranged symmetrically with respect to the X axis as a reference line, and the Y axis is set as a reference line In the biaxial four-point bending test apparatus in which the support point and the loading point are arranged in line symmetry, the arrangement of the support point and the loading point in the biaxial four-point bending test apparatus is set as a reference arrangement, with the Y axis interposed therebetween. The two support points are arranged at positions moved in the Y-axis direction so that two straight lines connecting the support points of each set are inclined at an angle other than 90 ° with respect to the Y-axis. You can also

  The first axis and the second axis are X and Y axes extending in directions orthogonal to each other, the support point and the loading point are arranged symmetrically with respect to the X axis as a reference line, and the Y axis is set as a reference line As a reference arrangement of the support point and the loading point in the biaxial four-point bending test apparatus in which the support point and the loading point are arranged in line symmetry, the intersection of the X axis and the Y axis is used as a reference. Of the two sets of support points arranged at point-symmetric positions as points, the two support points of one set each maintain a point-symmetric positional relationship with the intersection point of the X axis and the Y axis as a reference point As described above, it may be arranged at a position moved in the X-axis direction.

  According to the biaxial four-point bending test apparatus of the present invention, it is possible to measure the actual fatigue strength of the test piece by simulating the loading state close to the actual machine, and to improve the accuracy of the material soundness evaluation. Can be played.

It is a perspective view which shows the 1st Example of the biaxial four-point bending test apparatus of this invention. (A) is a top view which shows the 1st Example of the biaxial four-point bending test apparatus of this invention, (b) is IIb-IIb arrow line view of (a), (c) is IIc-IIc of (a). It is an arrow view. It is a top view which shows the stress state of the test piece in the 1st Example of the biaxial four-point bending test apparatus of this invention. It is a top view which shows the 2nd Example of the biaxial four-point bending test apparatus of this invention. It is a top view which shows the stress state of the test piece in the 2nd Example of the biaxial four-point bending test apparatus of this invention. It is a top view which shows the 3rd Example of the biaxial four-point bending test apparatus of this invention. It is a top view which shows the stress state of the test piece in the 3rd Example of the biaxial four-point bending test apparatus of this invention.

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

  1 to 3 show a first embodiment of the biaxial four-point bending test apparatus according to the present invention, in which four support points 2 are provided on one surface side (the lower surface side in the example of FIG. 1) of the flat test piece 1. Are spaced apart from each other in a first axial direction extending in one direction within the plane of the test piece 1 and a second axial direction extending in a direction intersecting the first axis at the central portion in the plane of the test piece 1. In addition, four loading points 3 are arranged apart from each other in the first axis direction and the second axis direction on the other surface side (upper surface side in the example of FIG. 1) of the test piece 1, and the first axis The load point 3 described above is disposed within the separation interval of the support point 2 in the direction (Sxs> Sxf in FIG. 2B), and the support point 2 is within the separation interval of the loading point 3 in the second axial direction. (Syf> Sys in FIG. 2 (c)), so that the central portion of the test piece 1 is pulled. And the stress and compressive stress is obtained by configured to generate a stress field crossing.

  In the case of the first embodiment, the first axis and the second axis are set as an X axis and a Y axis extending in directions orthogonal to each other, and the support point 2 and the loading point 3 are arranged symmetrically with respect to the X axis as a reference line. In addition, the support point 2 and the loading point 3 are arranged symmetrically with respect to the Y axis as a reference line.

  Next, the operation of the first embodiment will be described.

  When the bending test is performed by arranging the support point 2 and the loading point 3 as described above and applying a predetermined load by a testing machine (not shown), the test piece 1 is shown in FIG. As described above, when the tensile stress and the compressive stress intersect with each other and the angle between the tensile stress and the compressive stress is 90 ° (right angle), it is possible to generate a stress field in which the magnitudes of the maximum principal stress and the minimum principal stress are uniform. Incidentally, the direction in which the maximum principal stress (tensile) acts on the test piece 1 is coincident with the Y-axis direction, and the direction in which the minimum principal stress (compression) acts on the test piece 1 coincides with the X-axis direction. Become a shape.

  As a result, in the conventional four-point bending test apparatus as disclosed in Patent Documents 1 and 2, on the left and right sides of one axis extending in a direction penetrating the central portion of the test piece 1 horizontally. The fatigue strength data of the test piece 1 can only be obtained by so-called uniaxial loading in which a load is applied in the vertical direction, but the fatigue strength data of the test piece 1 obtained in the first embodiment is This is not a uniform stress due to uniaxial loading, but approximates the actual fatigue strength of the test piece 1, and the accuracy of the soundness evaluation of the material is greatly improved.

  In this way, the actual fatigue strength of the test piece 1 can be measured by simulating the loading state close to the actual machine, and the accuracy of the soundness evaluation of the material can be improved.

  4 and 5 show a second embodiment of the biaxial four-point bending test apparatus according to the present invention. In the figure, the same reference numerals as those shown in FIGS. The general configuration is the same as that of the first embodiment shown in FIGS. 1 to 3, but the feature of the second embodiment is that the supporting points in the first embodiment are as shown in FIGS. 2 and the loading point 3 are set as a reference arrangement, two straight lines L connecting the loading points 3 of the two sets of loading points 3 arranged in line symmetry with respect to the X axis. Each loading point 3 is located at a position moved in the X-axis direction so as to be inclined at an angle other than 90 ° with respect to the X-axis.

  Next, the operation of the second embodiment will be described.

  When the bending test is performed by arranging the support point 2 and the loading point 3 as described above and applying a predetermined load by a testing machine (not shown), the test piece 1 is shown in FIG. As shown in FIG. 5, when the tensile stress and the compressive stress intersect and the angle between them is other than 90 ° (right angle), the magnitude of the maximum principal stress is uniform, but the magnitude of the minimum principal stress varies (in FIG. 5). It is possible to generate a stress field (having a distribution that tends to increase the compression of the hatched portion). Incidentally, the direction in which the maximum principal stress (tensile) acts on the test piece 1 is the Y-axis direction, but the direction in which the minimum principal stress (compression) acts on the test piece 1 is a direction orthogonal to the straight line L. Thus, the shape does not coincide with the X-axis direction and is inclined.

  Here, in the conventional four-point bending test apparatus as disclosed in Patent Documents 1 and 2, on the left and right sides of one axis extending in a direction penetrating the central portion of the test piece 1 horizontally. The fatigue strength data of the test piece 1 can only be acquired by so-called uniaxial loading in which a load is applied in the vertical direction. However, the fatigue strength data of the test piece 1 obtained in the second embodiment is not a uniform stress due to the uniaxial loading, but approximates the actual fatigue strength of the test piece 1, and the soundness of the material The accuracy of sex evaluation is greatly improved. In addition to this, in the second embodiment, a complicated loading state in which a uniform maximum principal stress (tensile) and a minimum principal stress (compression) that is not uniform and has a strength distribution are combined. It is also possible to compare material strengths in more complex stress states by creating

  In the second embodiment, when the arrangement of the support points 2 and the loading points 3 in the first embodiment is a reference arrangement, two sets of support points are arranged opposite to each other symmetrically with respect to the Y axis. Even if each support point 2 is arranged at a position moved in the Y-axis direction so that two straight lines L connecting the support points 2 of each set of 2 incline at an angle other than 90 ° with respect to the Y-axis. It goes without saying that it is good.

  Thus, in the second embodiment, compared with the first embodiment, the actual fatigue strength of the test piece 1 can be measured by simulating the loaded state close to the actual machine, and the accuracy of the soundness evaluation of the material can be measured. Improvements can be made.

  6 and 7 show a third embodiment of the biaxial four-point bending test apparatus according to the present invention. In the figure, the parts denoted by the same reference numerals as those in FIGS. The general configuration is the same as that of the first embodiment shown in FIGS. 1 to 3, but the feature of the third embodiment is that the supporting points in the first embodiment are as shown in FIGS. 2 and the loading point 3 are set as a reference arrangement, and two of the two sets of the loading points 3 arranged at point-symmetrical positions with respect to the intersection O of the X axis and the Y axis as a reference point. Each loading point 3 is located at a position moved in the Y-axis direction so that a point-symmetrical positional relationship with the intersection point O between the X axis and the Y axis as a reference point is maintained.

  Next, the operation of the third embodiment will be described.

  When the bending test is performed by arranging the support point 2 and the loading point 3 as described above and applying a predetermined load by a testing machine (not shown), the center of the test piece 1 is shown in FIG. As shown in FIG. 7, the tensile stress and the compressive stress intersect with each other and the angle between the tensile stress and the compressive stress is 90 ° (right angle), the magnitude of the minimum principal stress is uniform, but the magnitude of the maximum principal stress varies (in FIG. It is possible to generate a stress field (having a distribution that tends to increase the tension at the hatched portion). Incidentally, the direction in which the maximum principal stress (tensile) acts on the test piece 1 is coincident with the Y-axis direction, and the direction in which the minimum principal stress (compression) acts on the test piece 1 coincides with the X-axis direction. Become a shape.

  Here, in the conventional four-point bending test apparatus as disclosed in Patent Documents 1 and 2, on the left and right sides of one axis extending in a direction penetrating the central portion of the test piece 1 horizontally. The fatigue strength data of the test piece 1 can only be acquired by so-called uniaxial loading in which a load is applied in the vertical direction. However, the fatigue strength data of the test piece 1 obtained in the third embodiment is not a uniform stress due to the uniaxial loading, but approximates the actual fatigue strength of the test piece 1, and the soundness of the material The accuracy of sex evaluation is greatly improved. In addition to this, in the third embodiment, a complicated loading state in which a maximum principal stress (tensile) having a distribution that is not simply uniform but strong and weak is combined with a uniform minimum principal stress (compression). It is also possible to compare material strengths in more complex stress states by creating

  In the third embodiment, when the arrangement of the support points 2 and the loading points 3 in the first embodiment is a reference arrangement, the position is point-symmetric with respect to the intersection point O between the X axis and the Y axis. The two support points 2 of one set out of the two sets of support points 2 arranged in the above are maintained in a point-symmetric positional relationship with the intersection point O between the X axis and the Y axis as a reference point. Needless to say, it may be arranged at a position moved in the X-axis direction.

  Thus, in the third embodiment, the actual fatigue strength of the test piece 1 can be measured by simulating a loading state that is more complicated than the first embodiment and is close to the actual machine, and the accuracy of the soundness evaluation of the material can be measured. Improvements can be made.

  Note that the biaxial four-point bending test apparatus of the present invention is not limited to the above-described embodiment. For example, the distance in the X-axis direction between the loading points 3 arranged symmetrically with respect to the Y-axis is determined. Needless to say, various changes can be made without departing from the gist of the present invention, such as being able to change between one set of loading points 3 and the other set of loading points 3.

1 Test piece 2 Support point 3 Loading point L Line O Intersection

Claims (5)

Four support points on one side of the flat test piece are separated from each other in a first axial direction extending in one direction within the plane of the test piece and a second axial direction extending in a direction intersecting the first axis. And placing the four loading points on the other surface side of the test piece, spaced apart from each other in the first axial direction and the second axial direction,
The test point is arranged such that the load points described above are disposed within the separation interval of the support points in the first axial direction, and the support points are disposed within the separation interval of the loading points in the second axial direction. Configure to generate a stress field where tensile stress and compressive stress intersect at the center of the piece ,
The first axis and the second axis are X and Y axes extending in directions orthogonal to each other, the support point and the loading point are arranged symmetrically with respect to the X axis as a reference line, and the Y axis is set as a reference line The support point and the loading point are arranged symmetrically as a biaxial four-point bending test apparatus. When the arrangement of the support points and the loading points in the biaxial four-point bending test apparatus according to claim 1 is set as a reference arrangement, each of the two sets of loading points arranged in line symmetry with respect to the X axis A biaxial four-point bending test apparatus in which each loading point is arranged at a position moved in the X-axis direction so that two straight lines connecting the loading points are inclined at an angle other than 90 ° with respect to the X-axis. Two sets arranged at point-symmetrical positions with the intersection of the X axis and the Y axis as a reference point when the arrangement of the support point and the loading point in the biaxial four-point bending test apparatus according to claim 1 is a reference arrangement. The two loading points of one set of the loading points are moved in the Y-axis direction so that a point-symmetrical positional relationship with respect to the intersection of the X-axis and the Y-axis is maintained. Biaxial four-point bending test equipment placed in When the arrangement of the support points and the loading points in the biaxial four-point bending test apparatus according to claim 1 is set as a reference arrangement, each of the two sets of support points arranged in line symmetry with respect to the Y axis. A biaxial four-point bending test apparatus in which each support point is moved in the Y-axis direction so that two straight lines connecting the support points are inclined at an angle other than 90 ° with respect to the Y-axis. Two sets arranged at point-symmetrical positions with the intersection of the X axis and the Y axis as a reference point when the arrangement of the support point and the loading point in the biaxial four-point bending test apparatus according to claim 1 is a reference arrangement. The two support points in one set of the support points are moved in the X-axis direction so that a point-symmetrical positional relationship with respect to the intersection of the X-axis and the Y-axis is maintained. Biaxial four-point bending test equipment placed in

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