Test system with strut braces

Abstract

The testing machine 10, 10' includes a base 12, at least one pair of struts 14 connected to the base 12, and a crosshead 16 connected to the struts 14 at a location remote from the base 12. At least one pair of specimen holders 20A, 20B are provided. A first specimen holder 20A is supported by the crosshead 16 and faces the base 12, and a second specimen holder 20B is supported by the base 12, which is connected to each of the struts 14 closest to the crosshead 16. An actuator 22 is connected in series between one of the specimen holders 20A, 20B and the corresponding base 12 or crosshead 16. Brace assemblies 30, 56, 80 are connected to each strut 14 at locations along its length between the base 12 and the crosshead 16 and span between the struts 14 to connect the struts 14 together or to the base 12 or crosshead 16.

Description

Background Art

[0001] The following discussion is provided only for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.

[0002] Physical tests of materials and / or components by taking test samples and applying tensile and / or compressive loads and / or displacements using an actuator are known. Generally, the tensile and compressive loads are applied alternately to the test sample at a selected frequency or over a range of frequencies at a constant displacement or amplitude. In the harmonic motion such as exists in this form of testing, the acceleration of the movable member of the actuator, sample grips, etc. is proportional to the product of the displacement amount and the square of the frequency. Thus, even if the amplitude is small (e.g., 0.06 mm), the acceleration can become very large at high frequencies (e.g., 700 Hz to 1000 Hz).

[0003] As a result, the force proportional to the product of the mass of the movable member and the acceleration also increases by the square of the frequency as the frequency increases. Further, this force must be reacted to by the structure of the test system, and the modes of the test system will be excited.

[0004] A general testing machine includes a base. The base includes upright columns that support a crosshead across the base. A first sample grip is coupled to the crosshead through a force transducer, while a second sample grip is coupled to the base using an actuator. However, the positions of the actuator and the force transducer may be reversed.

[0005] Due to the large dynamic force, vibration may occur during operation. One vibration mode that is considered unfavorable for testing is the "box mode" excited in the box-shaped structure of the crosshead, base, and support columns. This mode is unfavorable because it causes the force transducer (and / or displacement sensor) to move up and down due to these modes, resulting in errors in its corresponding output signal (which may also be plural).

Summary of the Invention

[0006] This summary is provided to introduce, in simplified form, some concepts that will be further described later in the detailed description. This summary is not intended to identify key features, essential features, or all features of the invention. Additionally, the description and claimed subject matter provided herein should not be construed as being related to addressing any of the drawbacks discussed in the background.

[0007] The testing machine includes a base, at least a pair of support columns joined to the base, and a crosshead joined to the support columns at a position away from the base. At least a pair of sample holders are provided. The first sample holder is supported by the crosshead and faces the base, and the second sample holder is supported by the base, and the base is the portion joined to each of the support columns closest to the crosshead. An actuator is serially connected between one of the sample holders and the corresponding base or the crosshead. A brace is connected to each of the support columns and extends between the support columns. The brace is connected to each of the support columns at a position along its length between the base and the crosshead.

[0008] The embodiments can include one or more of the following features. The brace can be connected to each of the support columns at various positions. In a first embodiment, the brace is connected to each of the support columns between the ends of the sample holders that are remote from each other. On the other hand, in another embodiment, it may be preferable to connect the brace to each of the support columns between the ends of the sample holders that are closest to each other.

[0009] Some preferred ranges include positioning the braces connected to each of the struts at a distance in the range of about 25% to 75% between the ends of the sample holders closest to each other. In a further embodiment, the braces are connected to each of the struts at a distance in the range of about 40% to 60% between the ends of the sample holders closest to each other. The braces can also be connected to each of the struts at about 50% of the distance between the ends of the sample holders closest to each other.

[0010] Each strut has an axis, and the brace can have a portion that extends along a plane between the struts parallel to the plane having the axes of both struts. The portions at each end of the brace are joined to opposite side portions of the outer surface of each strut along the bisecting plane of each strut, and the bisecting plane is perpendicular to the plane extending between the struts. The brace can have an opening through which the axis between the sample holders can extend. Desirably, the brace can have a removable portion that defines part of the opening, thereby facilitating insertion and removal of the test sample without removal of the brace or movement of the brace along the strut.

[0011] Typically, the testing machine includes at least a pair of struts, although additional struts such as four struts may be provided. In the case of three or more struts, a second brace can be connected between two struts different from the first brace, and the second brace is connected to each of the respective struts at a position along its length at least between the ends of the sample holders remote from each other. Depending on the number of struts, the testing machine may include a third brace and a fourth brace, and the brace, the second brace, the third brace, and the fourth brace each connect adjacent struts around a periphery surrounding the axis extending between the sample holders.

[0012] The struts can extend through the base. In such an embodiment, the ends of the struts on the side of the base remote from the crosshead are typically joined together. Similarly, the struts can extend through the crosshead, in which case the ends of the struts on the side of the crosshead remote from the base are joined together.

[0013] Also, the testing machine includes a base, at least a pair of struts joined to the base, a crosshead joined to the struts at a position remote from the base, at least a pair of sample holders, wherein the first sample holder is supported by the crosshead and faces the base, the second sample holder is supported by the base, the base is a portion joined to each of the struts closest to the crosshead, at least a pair of sample holders, one of the sample holders, and an actuator serially connected between the corresponding base or the crosshead.

[0014] The testing machine includes a base, at least a pair of struts joined to the base, and a crosshead joined to the struts at a position remote from the base. At least a pair of sample holders are provided. The first sample holder is supported by the crosshead and faces the base, the second sample holder is supported by the base, and the base is a portion joined to each of the struts closest to the crosshead. An actuator is serially connected between one of the sample holders and the corresponding base or the crosshead. A brace assembly is connected to each of the struts at a position along the length of each strut between the base and the crosshead, and the brace assembly extends between the struts to connect the struts together or to connect to the base or the crosshead. In a first embodiment, the brace is connected to the struts at a position remote from the base and the crosshead and extends between the struts. Additionally or alternatively, the brace assembly can include gussets connected to each strut, with a first end of the gusset connected to the strut and a second end connected to the base or the crosshead.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

DETAILED DESCRIPTION OF THE INVENTION

[0016] A schematic view of a testing machine 10 for applying force or motion to a test sample (not shown) is shown in FIG. 1. The testing machine includes a frame 11 having a base 12, a pair of struts 14 extending upward from the base 12, and a crosshead 16 joined to two of the struts 14 at a position away from the base 12. At least a pair of sample holders 20A, 20B are provided. The first sample holder 20A is supported by the crosshead 16 and extends toward the base 12. The second sample holder 20B is supported by the base 12 and extends toward the crosshead 16. It should be noted that the base 12 is the part of the testing machine 10 joined to each of the struts 14 closest to the crosshead 16.

[0017] The actuator 22 is connected in series between one of these sample holders 20A, 20B and the corresponding base 12 or the crosshead 16. In the illustrated embodiment, the first sample holder 20A is joined to a force transducer 24 supported by the crosshead 16, while the second sample holder 20B is coupled to the actuator 22 within the base 12. It should be noted that in another embodiment, the actuator 22 is located within the crosshead 16, while the force transducer 24 is, in this case, joined to the base 12.

[0018] Referring to FIGS. 3 and 4, a brace assembly, exemplified herein as brace 30, is connected to each support column 14 and extends between the support columns 14. The brace 30 is connected to each of the support columns 14 at a position along its length between the base 12 and the crosshead 16. The testing machine 10 has several resonant vibration modes. One important vibration mode is generally referred to as the "box mode". When the brace 30 that joins the support columns 14 together is generally added at the middle of the support columns 14 between the base 12 and the crosshead 16, the box mode frequency increases significantly compared to the testing machine without the brace 30. FIGS. 5 and 6 respectively show exaggerated images of the testing machine 10 without the brace 30 and with the brace 30. In FIG. 5, the testing machine 10 without the brace 30 is generally deformed significantly at the middle of the support columns 14, and the deformation decreases as it progresses downward toward the base 12 and upward toward the crosshead 16.

[0019] In FIG. 6, the brace 30 extends between the support columns 14. Although additional deformation may occur at the crosshead 16, the deformation at the middle of the support columns 14 is significantly reduced. More importantly, the box mode resonance frequency increases from approximately 715 Hz in the state without the brace 30 to approximately 824 Hz in the state with the brace 30. FIG. 7 shows the box mode resonance frequencies of samples of different lengths.

[0020] In FIGS. 3 and 6, the state where the brace 30 is disposed around the middle of the support column 14 is illustrated, but other positions along the support column 14 can provide benefits. Generally, the brace 30 is connected to each of the support columns 14 at a position along its length between the ends of the sample holders 20A and 20B that are remote from each other. In a further embodiment, the brace 30 is connected to each support column 14 between the ends of the sample holders 20A and 20B that are closest to each other. In a further embodiment, the brace 30 is connected to each support column 14 at a position at a distance in the range of about 25% to about 75% between the ends of the sample holders 20A and 20B that are closest to each other. In yet another embodiment, the brace 30 is connected to each of the support columns at a position at a distance in the range of about 40% to about 60% between the ends of the sample holders 20A and 20B that are closest to each other. The brace 30 can also be connected to each support column 14 at a distance of about 50% between the ends of the sample holders 20A and 20B that are closest to each other.

[0021] Each support column 14 has an axis 32, and the brace 30 has a portion 40 that extends along a plane 41 between the support columns 14 parallel to a plane 43 having the axes 32 of both support columns 14. In one embodiment, the portions 40 at each end of the brace 30 are joined to opposite side portions of the outer surfaces of the respective support columns 14 at the bisecting plane 45 of each support column 14, and the bisecting plane 45 is perpendicular to the plane 43 that extends between the support columns 14. It is considered that the maximum rigidity is provided to the support column 14 by disposing or joining the brace 30 at a point on the outer surface of the support column 14 that coincides with the bisecting plane 45. Typically, the brace 30 is attached to the support column 14 so as to provide a structural element such as the portion 40 that extends in a plane perpendicular to the axis of the support column 14.

[0022] Referring to FIG. 4, the brace 30 can have an opening 42 through which the axis 44 (FIG. 2) extends between the sample holders 20A, 20B. Thus, the opening 42 allows the test sample to be joined to the sample holders 20A, 20B along the axis 44 without contact with portions of the brace 30. The opening 42 can be sized such that the ends of the test sample can extend through the opening 42 during load generation and then the ends of the test sample can be attached to the other sample holders 20A, 20B. In an exemplary embodiment, the diameter of the support 14 is relatively large and may be wider than the test sample being tested, but the brace 30 may have an opening that is approximately the same as or larger than the diameter of the support 14. In this case, the portion of the brace 30 extending between the supports 14 may curve outwardly in one or both of the directions indicated by the double-headed arrow 47 to provide a larger opening if necessary. It should be noted that the illustrated configuration of the brace 30 should not be considered limiting in this regard.

[0023] In a further embodiment, a portion 46 of the brace 30 that defines a part of the periphery of the opening 42 is removable to allow insertion or removal of the test sample into or from the opening 42. Thereafter, when the test sample is attached to the sample holders 20A, 20B, the portion 46 is reattached. The removable portion 46 can be joined to the other parts of the brace 30 using a suitable fastener 48 such as a threaded bolt. In another embodiment, the portion 46 can be hingedly connected at one end so that only one fastener is required to secure the portion 46 to the other parts of the brace 30.

[0024] The ends 30A, 30B of the brace are fixed to the supports 14, for example, to their outer surfaces. In one embodiment, each of the ends 30A, 30B comprises a clamp that sandwiches the outer surface of the support 14. For example, the clamps at each end 30A, 30B can include a split collar having one or more suitable fasteners 51 such as threaded bolts, which can reduce or increase the inner diameter of the brace 30 (or even attach separate parts together) to sandwich the outer surface of the support 14.

[0025] The brace 30 disclosed in this specification is not limited to a testing machine having only a pair of struts, and it should be noted that it can be used with a testing machine having a plurality of other struts. FIG. 8 is a schematic top cross-sectional view of a testing machine 10' having four struts 14. In such a testing machine, a plurality of braces 52, 53, 54, and 55 (similar to the brace 30) are used between adjacent struts 14 so that the individual braces 52 to 55 form a structure 56 that extends between adjacent struts. Additionally or alternatively, the braces 58, 59 can extend, for example, diagonally between non-adjacent struts 14 when the four struts 14 are arranged in a square or rectangle. Thus, the diagonally extending braces 58, 59 can extend to or bisect the test sample axis that extends between the sample holders, and for this reason, the braces 58, 59 can also have an opening similar to the opening 42 of the brace 30.

[0026] Referring again to FIG. 1, the testing machine 10 has struts 14 that extend through the base 12 to a connecting element 70 that joins the ends of the struts 14 on the side of the base 12 remote from the crosshead 16. Similarly, if desired, the struts 14 can extend through the crosshead 16 as shown by the dashed line and connect to a structural element 72 on the end of the crosshead 16 remote from the base 12. In the embodiment of FIG. 1, the base 12 is movable along the struts 14 and is selectively fixed to the struts 14 using a clamping device 80 that includes a pneumatic actuator or a hydraulic actuator that sandwiches a portion of the base 12 against the outer surface of the struts 14. The base 12 is adjustable to change the distance between the sample holders 20A, 20B according to the length of the test sample being tested.

[0027] Figure 3 shows another form of brace assembly 80 that includes one or more gussets 81, 82, 83, 84 (shown schematically) that are connected to the support strut 14 at a location shown above, for example, intermediate the base 12 and the crosshead 16, or in a first portion thereabout. The gussets 81 - 84 can be attached to the support strut 14 using the split collar found on the brace 30. The gussets 81 - 84 are also firmly fixed to the base 12 as shown, but may be fixed to the crosshead 16 if desired.

[0028] Although the subject matter has been described in terms of words specific to particular environments, structural features, and / or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the particular environments, specific features, or acts described above as determined by a court. Rather, the above-described environments, specific features, and acts are disclosed as illustrative forms of implementing the claims. Some aspects of the present invention are described below. [Aspect 1] A base, At least a pair of columns joined to the base, A crosshead joined to the columns at a position away from the base, At least a pair of sample holders, wherein the first sample holder is supported by the crosshead and faces the base, the second sample holder is supported by the base, and the base is a portion joined to each of the columns closest to the crosshead, at least a pair of sample holders, An actuator serially connected between one of the sample holders and the corresponding base or the crosshead, A brace connected to each of the columns and extending between the columns, and the brace is connected to each of the columns at a position along its length between the base and the crosshead, a testing machine comprising the brace. [Aspect 2] The testing machine according to Aspect 1, wherein the brace is connected to each of the columns between the ends of the sample holders remote from each other. [Aspect 3] The testing machine according to Aspect 1 or 2, wherein the brace is connected to each of the columns between the ends of the sample holders closest to each other. [Aspect 4] The testing machine according to any one of Aspects 1 to 3, wherein the brace is connected to each of the columns at a position at a distance in the range of about 25% to 75% of the distance between the ends of the sample holders closest to each other. [Aspect 5] The testing machine according to Aspect 4, wherein the brace is connected to each of the columns at a position at a distance in the range of about 40% to 60% of the distance between the ends of the sample holders closest to each other. [Aspect 6] The testing machine according to Aspect 5, wherein the brace is connected to each of the columns at a position at a distance of about 50% of the distance between the ends of the sample holders closest to each other. [Aspect 7] The testing machine according to any one of Aspects 1 to 6, wherein each column has an axis, and the brace has a portion extending along a plane between the columns parallel to a plane having the axis of both columns. [Aspect 8] The testing machine according to Aspect 7, wherein the portions at each end of the brace are joined to opposite side portions of the outer surface of each column along a bisecting plane of the column, and the bisecting plane is perpendicular to the plane extending between the columns. [Aspect 9] The testing machine according to any one of Aspects 1 to 8, wherein the brace has an opening through which an axis between the sample holders extends. [Aspect 10] The testing machine according to aspect 9, wherein the brace has a removable portion that defines a part of the opening. [Aspect 11] The testing machine according to any one of aspects 1 to 10, wherein the at least one pair of struts includes four struts, and a second brace is connected between two struts different from the brace, and the second brace is connected to each of the respective struts at a position along its length between ends of the sample holders remote from each other. [Aspect 12] The testing machine according to aspect 11, further comprising a third brace and a fourth brace, wherein the brace, the second brace, the third brace, and the fourth brace respectively connect adjacent struts around a periphery surrounding an axis extending between the sample holders. [Aspect 13] The testing machine according to any one of aspects 1 to 12, wherein the actuator is disposed within the base. [Aspect 14] The testing machine according to aspect 13, wherein the struts extend through the base. [Aspect 15] The testing machine according to aspect 14, wherein ends of the struts on a side of the base remote from the crosshead are joined together. [Aspect 16] The testing machine according to any one of aspects 1 to 12, wherein the actuator is disposed within the crosshead. [Aspect 17] The testing machine according to aspect 16, wherein the struts extend through the crosshead. [Aspect 18] The testing machine according to aspect 17, wherein ends of the struts on a side of the crosshead remote from the base are joined together. [Aspect 19] A base, at least one pair of struts joined to the base, a crosshead joined to the struts at a position remote from the base, at least one pair of sample holders, wherein a first sample holder is supported by the crosshead and faces the base, a second sample holder is supported by the base, and the base is a portion joined to each of the struts closest to the crosshead, an actuator connected in series between one of the sample holders and the corresponding base or crosshead, and a brace assembly connected to each of the struts at a position along the length of each strut between the base and the crosshead, the brace assembly spreading between the struts to connect the struts together or to connect to the base or the crosshead. [Aspect 20] The testing machine according to aspect 19, wherein the brace assembly is connected to the support column at a position away from the base and the crosshead, and includes a brace that extends between the support columns. [Aspect 21] The testing machine according to aspect 19, wherein the brace assembly includes gussets connected to each support column, a first end of the gusset is connected to the support column, and a second end of the gusset is connected to the base or the crosshead.

Description of Symbols

[0029] 10 Testing machine 11 Frame 12 Base 14 Support column 16 Crosshead 20A First sample holder 20B Second sample holder 22 Actuator 24 Force transducer 30 Brace 30A End 30B End 32 Shaft 40 Portion 41 Plane 42 Opening 43 Plane 44 Shaft 45 Bisecting plane 46 Removable portion 48 Fastener 51 Fastener 52 Brace 53 Brace 54 Brace 55 Brace 58 Brace 59 Brace 70 Connecting element 72 Structural element 80 Clamping device 81 Gusset 82 Gusset 83 Gusset 84 Gusset

Claims

1. a base; a pair of struts joined to the base and extending parallel to each other; a crosshead joined to the pair of struts at a position remote from the base; a pair of sample holders including a first sample holder supported by the crosshead and facing the base, and a second sample holder supported by the base and coaxially arranged with respect to the first sample holder; an actuator serially connected between one of the first and second sample holders and the corresponding base or crosshead; a brace connected to each of the pair of struts and extending between the pair of struts; the brace has an opening through which the axis between the first and second sample holders extends, and a removable portion defining a part of the opening, a testing machine.

2. Each strut has an axis, and the brace has a portion extending along a plane between the struts parallel to a plane having the axes of both struts, the testing machine according to Claim 1.

3. The portion extending along the plane between the struts at each end of the brace is joined to opposite side portions of the outer surface of each strut along a bisecting plane of each strut, the bisecting plane being perpendicular to the plane extending between the struts, the testing machine according to Claim 2.

4. The at least one pair of struts includes four struts, a second brace is connected between two struts different from the brace, and the second brace is connected to each of the struts at a position along its length between ends of the sample holders remote from each other, the testing machine according to Claim 1.

5. further comprising a third brace and a fourth brace, the brace, the second brace, the third brace and the fourth brace each connecting adjacent struts around a periphery surrounding an axis extending between the sample holders, the testing machine according to Claim 4.

6. The actuator is disposed within the base, the testing machine according to Claim 1.

7. The struts extend through the base, the testing machine according to Claim 6.

8. The ends of the struts on the base side remote from the crosshead are joined together, the testing machine according to Claim 7.

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