A SHEAR TEST SETUP FOR COUNTERSUNK HEAD SCREW FASTENERS
Patent Information
- Application Number
- TR202522918U
- Authority / Receiving Office
- TR · TR
- Patent Type
- Utility models
- Current Assignee / Owner
- Filing Date
- 2025-12-30
- Publication Date
- 2026-08-21
- Estimated Expiration
- 2035-12-30
Abstract
Description
1 TARIFF A SHEAR TEST FOR COUNTERSUNK HEAD SCREW FASTENERS mechanism Technical Area The invention relates to the experimental design of mechanical fasteners and structural components in general. test systems for testing purposes; specifically, countersunk head screws. 10 developed for determining the shear strength of fasteners It relates to test setups. Countersunk threaded fasteners are characterized by their head geometry, body structure, and partial threading. When considered together with their regions, especially aviation, defense industry and high Widely used in assembly applications requiring structural reliability, 15 Mechanical performance is critical for these components. These types of fasteners include: different types and sizes with standardized measurements and serial identifications They can be produced in combinations and are used in practice with codes such as HL23-5, HL23-6. The countersunk head screw fittings described are examples of this group. The subject is the loading conditions to which fasteners are subjected throughout their service life, 20 not limited to tensile forces, but also shear forces acting in different directions It also includes. Therefore, the fasteners are under shear load. experimentally accurate and reliable determination of their behavior, structural safety and is important in terms of product qualification. Shear tests examine the shear rate of fasteners under a specific loading pattern. The aim is to measure the mechanical resistance they exhibit against the forces, test The accuracy of the results largely depends on the geometric fit of the test setup used and It depends on the load transfer characteristics, especially complex bow and fuselage geometries. In fasteners with a shear load of 30, it is controlled, repeatable, and avoids unwanted shear loads. It can be administered without causing side effects, and the test subject remains stable throughout the testing process. specially designed test setups that enable its positioning in this manner are required It makes it possible. 2 In this context, the invention relates to the use of countersunk threaded fasteners during shear tests. ensuring that the load is transferred to the test element in the intended direction and in a stable manner; It relates to a shear testing setup that can be used with universal testing machines. The device described within the scope of the invention has geometric properties of the connecting element. Taking this into consideration, the shear test process is reliable and repeatable. 5 It is structured in a way that will allow it to be implemented. State of the Art Countersunk threaded fasteners are used in 10 industries, primarily the aerospace and defense industries. Used in structural assemblies that are critical for safety, with tight geometric tolerances. These are mechanical elements that require high strength and functional reliability. This type of Within the scope of mechanical characterization of fasteners, tensile behavior is also considered. The behavior under shear loads was also experimentally determined in accordance with standards. This needs to be verified. Indeed, small-diameter aviation-grade screw pins, 15 In practice, as seen in examples identified by serial codes such as HL23-5, HL23-6, Due to their geometric constraints, they are directly tested on universal testing machines. The inability to do so necessitates a custom fixture design. In terms of shear testing, the current state of the art, along with universal testing machines, is 20 It is known that different types of cutting devices are used. One of these devices is... In this section, the load is applied through a sample positioned between two plates or jaws. is transferred; in some cases, the shear force is transmitted through a pin-like element at a specific shear angle. It is applied in such a way as to cause it to break in the plane. However, countersink Head geometry, body form and partial threaded structure of head screw fasteners 25 When considered together, most standard cutting tools are perfectly suited to this geometry. It appears that it cannot adapt. The geometric mismatch, especially in load transfer... not occurring as planned, axis misalignment, and during testing This can lead to the introduction of unwanted bending moments. Such side effects... The effects can lead to an incorrect assessment of the shear strength parameter that is intended to be measured, and 30 This can lead to a decrease in the repeatability of test results. One of the main problems encountered in the current state of the art is the controlled and efficient handling of the load. The problem is that it cannot be applied symmetrically. In shear tests, the fixture of the test element... The areas where it comes into contact with surfaces are often limited and sensitive to tolerances. 3 These areas are formed by the proper guidance of the surfaces that fit into the hole, in particular. If centering is not ensured, the contact conditions between the test element and the fixture This can vary from sample to sample; this affects both the stress distribution and the fracture. It directly affects the mode. As a result, on the same type of fastener... Even in successive tests, deviations in terms of fracture load and fracture characteristics were observed. 5 It can occur. Another problem is the occurrence of local stress concentrations during shear loading. This refers to the edges of holes, transition surfaces, and the initial contact points of the load in shear fixtures. These areas are typically considered critical zones. Suitable surface forms and sufficient resources are essential in these zones. Permanent deformations occur in fixture components when cross-sectional area and rigidity cannot be ensured. These deformations can occur, repeatedly compromising the geometric accuracy of the fixture. This can jeopardize measurement accuracy and structural integrity in tests. Indeed, cutting In the test setup, the critical component is most commonly used due to the load transfer characteristics. It is considered a top fixture and in some material and design combinations, it is among the top 15. In technical assessments where there is a risk of permanent deformation in the fixture It is stated. Another limitation seen in the known state of the art is that most cutting fixtures The problem is poor adaptability in terms of size and diameter. It can accommodate 20 different diameter and size combinations. Testing fasteners that have similar geometric characteristics. For this purpose, often separate fixtures or separate sets of intermediate elements are used for each measurement group. This approach increases both fixture costs and testing requirements. It reduces the operational efficiency of the infrastructure. Also, between different fixture sets... The variation in tolerance, rigidity, and contact conditions results in obtaining elements of different sizes. This makes it difficult to compare the test results with each other. In shear tests, compatibility with a universal testing machine is also an important requirement. In many applications, the total length of the fixture assembly is equal to the minimum jaw length of the testing machine. practical constraints such as clearance, parallelism of mounting surfaces and assembly ergonomics 30 It is limited in this context. In this regard, it is as important that the fixture can be connected to the testing machine as it is; It is also important that the assembly is quick, safe and repeatable. Otherwise, the test... Errors that occur during the pre-installation process affect the accuracy of test results and This can negatively affect its repeatability. 35 4 Another problem that stands out in the known state of the art is the fixture during testing. load due to relative movements and assembly clearances that may occur between components It is a change in the transmission path. Multi-part components assembled with connecting elements. in fixtures, when sufficient surface fit cannot be achieved or the clamping pattern is not symmetrical When it cannot be installed, part of the shear load is lost through unwanted contact points. 5 It is portable; this results in unpredictable stresses on both the fixture and the test element. It is able to create these components. This is especially true on fixture surfaces during repeated testing. wear and permanent marks, and therefore changes in contact conditions over time. This can be the reason. In addition, in some known setups used in shear tests, the test element Secondary geometric features, such as gear area or head geometry, during loading It can be activated involuntarily; this is the main thing that the shear test aims to measure. This leads to the behavior being masked by unwanted contact and friction effects. It can open. In practice, this situation means that the sample is 15 inches outside the designed cutting plane. causing damage or different modes of rupture It can provide. Consequently, the measurement obtained is as important as the conformity of the test to the standard. The representativeness of the data may also weaken. Consequently, in the current state of the art, there are 20 countersunk threaded connection elements. For use in determining shear strengths, with universal testing machines. capable of working together, transferring the load in the intended direction and in a repeatable manner, Rigid and durable in a way that reduces the risk of permanent deformation in fixture components, It also provides adaptability for elements of different sizes but with similar geometry. It is assessed that the need for a shear test setup continues. This 25 the need, especially for aviation types that cannot be directly tested due to geometric constraints. This becomes more pronounced in screw pin applications. Purpose of the Invention The main purpose of the invention is to increase the shear strength of countersunk threaded fasteners. During experimental determination, structural abnormalities encountered in the known state of the art. and a reliable and repeatable shear test to resolve measurement problems. The goal is to ensure the connection is secure, especially for connections with complex head and body geometries. The components are designed to be used in conjunction with universal testing machines, in a controlled manner and 35 to enable testing of the invention under a predictable loading schedule It is among the primary objectives. Another objective of the invention is to reduce the load applied to the test specimen during shear testing. by ensuring that the load is transferred along a stable load path throughout the process, axial misalignment, 5 The aim is to prevent the occurrence of unwanted bending moments and lateral load components. In this way, the fastener subjected to the shear test will only withstand the intended shear test. subjected to load and test results will reflect the actual mechanical behavior. The aim is to obtain it in this way. Another purpose of the invention is to create a barrier between the test element and the test setup during shear tests. by eliminating potentially irregular contact conditions, localized contact on contact surfaces The aim is to reduce stress concentrations and the associated risk of premature damage. In this context, testing... holding the component in a stable and repeatable position within the test setup One of the key objectives of the invention is to present a structure that provides this. Thus, test 15 during which the breaking load and breaking mode are independent of fixture-induced effects The aim is to observe. Another objective of the invention is to enable the shear test setup to be directly integrated into universal testing machines. Designed with a connectable structure, it allows for the addition of 20 adapters or complex mounting systems. The goal is to reduce the need for it. In this context, the assembly of the test setup is easy, fast and... structuring it in a way that minimizes operator dependency; saving time in testing processes. The aim is to prevent losses and assembly errors. Another aim of the invention is to create 25 different sizes of metals with similar geometric characteristics. Shear testing of countersunk threaded fasteners using the same test setup. The aim is to provide a structure that allows for its implementation. In this context, HL23- Including fasteners with serial designations such as 5, HL23-6, etc. Similar geometric elements from different size groups can be tested through a single testing infrastructure. The aim is to enable evaluation. Thus, each link 30 the need to design and manufacture separate test apparatus for element size reduction; achieving operational efficiency and cost advantages in test infrastructure. that is intended. 6 Another objective of the invention is to enable the components that make up the test setup during shear testing, structural integrity and geometric precision under the loads they are subjected to The goal is to structure the test setup in a way that will protect against repeated testing. Accordingly, the test setup should be designed for repeated testing. usability without loss of performance, reduction of the risk of permanent deformation. and is intended to produce reliable results with long-term use. 5 Finally, the purpose of the invention is to perform shear tests on countersunk threaded fasteners. by increasing the accuracy and comparability of the experimental data obtained in relation to the product in qualification, quality control processes and standards compliance assessments The goal is to create a reliable testing infrastructure that can be used. This will enable connection 10 the mechanical performance that its components will demonstrate under actual operating conditions The aim is to ensure proper evaluation and to improve application security. The invention is designed to fulfill the purposes stated above; it consists of a countersunk head at the top and this countersunk head... a cylindrical body attached to the head and extending in the axial direction, with 15 on that body experimental shear strength of test elements containing a toothed section It is a shear test setup designed to determine the fixation during the shear test. acting as a reference element, it will not change position during the test. a structured sub-fixture, by universal testing machine during shear test An upper fixture that is moved in the tensile direction and applies a shear load to the test element, 20 The sub-fixture on which the test element to be subjected to the shear test is located. placement inside and the test element at the determined position before the shear test at least one through which the test element is passed, allowing it to be held in place. The connection gap allows the upper fixture to be controlled in conjunction with the lower fixture during the shear test. 25 It can interact and a movement directed towards the lower fixture. an entry opening on the upper fixture that enables the shear test to be performed during the process, the test element makes contact with the cylindrical body part and through this part a device that allows the application of shear load, through which the test element's body is passed. and aligned on the same shear plane as the connection gap on the lower fixture It includes a cutting gap. 30 Explanation of the Figures Figure 1 shows the determination of the shear strength of countersunk threaded fasteners. A shear test device configured for this purpose, with a fixed lower fixture and a movable upper fixture. It shows the general appearance of the mechanism. 35 7 Explanation of Part References A. Test Setup 10th Sub-Fixture 11. Connection Gap 5 12. Inlet Opening 13. Second Connection Gap 20th Top Fixture 21. Cutting Gap 22. Second Section Gap 10 30. Test Technician Detailed Description of the Invention The invention relates to countersunk threaded fasteners, briefly referred to as test 15 in the invention. experimental determination of the shear strength of element (30) It relates to a developed shear test setup (A). The test described within the scope of the invention setup (A); a lower fixture (10), an upper fixture (20) and a test to be subjected to shear test. The test setup in question (A) is structured to include element (30). Threaded fasteners with countersunk head geometry can be tested with universal testing machines in 20... By using them together, they undergo a controlled, reliable and repeatable shear test. It makes it possible to hold the test element (30) countersunk elements such as Hi-Lok. It represents and the head angle is usually between 100° and 130°. The basic technical approach of the invention is that the test element (30) during the shear test is 25 beforehand. on a defined shear plane and with unwanted bending moments and lateral loads In order to ensure that the components are loaded before they are formed, the lower fixture (10) and the upper fixture (20) geometrically compatible, with limited relative motion and load path control. It is based on the principle of arranging it in a structure. Thanks to this structure, shear testing The forces applied during the test are transferred to the test element (30) in the predicted direction and 30 The accuracy of measurement results is being improved. The lower fixture (10) acts as a fixed reference element during the shear test. a highly rigid structure configured so that it will not change position during its duration It is a body element. On the lower fixture (10), the test element to be subjected to the shear test is 35 8 (30) at least one connection gap that allows placement into the sub-fixture (10). (11) is located. The connection gap (11) is located in the cylindrical body part of the test element (30). so that it can be positioned by passing it through the lower fixture (10). It is structured. Thanks to this connection gap (11), the test element (30) can perform a shear test. It is held in the correct position beforehand and in accordance with the specified cutting plane. 5 On the lower fixture (10), in addition to the connection gap (11), different diameters, thicknesses or to enable test elements of dimensions (30) to be subjected to shear testing A second connection gap (13) can also be configured. Second connection gap (13) performs the same function as the connection gap (11) and the same sub-fixture (10) 10 Testing of test elements with different dimensions in an alternating position. This allows for separate testing of different test element geometries. Multiple via a single sub-fixture (10) without the need to produce sub-fixtures (10). Test scenarios can be conducted. In addition, on the lower fixture (10), the lower fixture (10) during the shear test of the upper fixture (20) an entrance opening that allows it to move into it in a controlled manner (12) It is located. The entrance opening (12) is where the upper fixture (20) interacts with the lower fixture (10). It defines the region and directs the upper fixture (20) throughout the testing process and It enables stable relative motion along the cutting plane. 20 The upper fixture (20) acts as the element applying the live load during the shear test. a body that is made and moved in the tensile direction by a universal testing machine It is an element. The upper fixture (20) passes through the entrance opening (12) on the lower fixture (10). It is positioned to interact with the lower fixture (10) by passing through. This interaction is 25 thanks to the tensile force applied by the upper fixture (20), test element (30) It is oriented in such a way as to create a shear force on it. On the upper fixture (20), the shear plane on which the shear test will be performed is defined. There is a shear clearance (21). The shear clearance (21) is 30 of the test element (30). The cylindrical body section is passed through and during the shear test this body It is configured to allow loading via the section. Cutting gap (21) is on the same cutting plane as the connection gap (11) on the lower fixture (10). It is positioned in such a way as to be aligned. Thanks to this alignment, the test element (30), During the shear test, it is loaded only on the defined shear plane. Shear 35 9 In order for the test to be carried out reliably and repeatably, the test element (30) The shape of the upper fixture (20) applying the shear load under load during the test period The aim is to construct it with high rigidity so that it will not change. In this context... higher hardness of the upper fixture (20) compared to the mechanical properties of the test element (30) It is designed to have the following values, so that the applied shear load is 5 It is ensured that the focus is solely on the test element (30). This upper fixture (20) made of heat-treated hardened steel material to enable it to perform its function. It was preferred to manufacture it in this way, thus enabling fixture-based measurements during the test. This prevents errors and result deviations. On the upper fixture (20), in addition to the cutting gap (21), different diameter or thickness to enable the test elements (30) to be subjected to shear testing A second shear gap (22) can also be configured. The second shear gap (22) is located below to work together with the second connection gap (13) on the fixture (10) and the same It is positioned aligned on the cutting plane. This structure is the same as the sub-fixture 15 By creating an alternative shear test station on (10) and the upper fixture (20), different It makes it possible to test test elements with specific dimensions. Connection gap (11), second connection gap (13), cutting gap (21) and second cutting The gap (22) varies depending on the geometric properties of the test element (30) to be tested. to have different widths, different depths and different cross-sectional geometries It can be configured. In this way, different dimensions and tolerances can be achieved with the same test setup (A). Cutting tests can be performed on the test elements that have it. The test element to be subjected to the shear test (30) is a countersunk head threaded connection element 25 and during the test, it was subjected to shear load on the cylindrical body section. Test element (30) is left on the connection on the lower fixture (10) before testing. When the gap (11) and the shear gap (21) on the upper fixture (20) are aligned, It is positioned by passing it through the gaps in question. Alternative test In the scenarios, the test element (30), the second connection gap (13) and the corresponding 30 It is placed through the second cutting gap (22). After the assembly operations are completed, the upper fixture (20) is tested by the universal testing machine. It is moved in the direction of pulling and as a result of this movement it makes contact with the upper fixture (20). The cylindrical body part of the test element (30) in the condition is subjected to shear load 35 remains. Test element (30), cutting gap (21) or second cutting gap (22) It is subjected to fracture on the shear plane defined by; at the moment of fracture The test is completed by measuring the obtained load values. Thanks to this structure, the shear strength, fracture load and fracture of the test element (30) 5 The behavior can be determined in a reliable, repeatable, and standards-compliant manner. The configuration of the fixture (10) to be fixed and the upper fixture (20) to be movable, cutting This ensures stable identification of the load path during testing and measurement. It increases the accuracy of the results. The lower fixture (10) and the upper fixture (20) were subjected to high shear during the shear test. to maintain their structural integrity and geometric precision under the given forces It is constructed from a metal material. This allows for countersunk screw fittings. Technical problems encountered in shear tests of fasteners effectively These problems are being eliminated and highly accurate experimental results are being obtained. 15
Claims
11 REQUESTS 1. The invention relates to a device with a countersunk head at its upper end and an axially extending structure adjacent to this countersunk head. It consists of a cylindrical body and a toothed section formed on that body. 5 for experimental determination of the shear strength of test elements (30) a shear test setup (A) whose characteristic is; ● a fixed reference element that serves during shear testing, test a sub-fixture configured in such a way that it will not change position during the period (10), ● During the shear test, the universal testing machine moves in the tensile direction 10 an upper fixture (20) which is driven and applies shear load to the test element (30), ● the test element to be subjected to the shear test on the said sub-fixture (10) (30) placement into the lower fixture (10) and shear test of the test element (30) allowing the test element (30) to be held in the position determined beforehand at least one connection gap through which the body part passes (11), 15 ● the upper fixture (20) is controlled in conjunction with the lower fixture (10) during the shear test. to be able to interact and a movement directed into the sub-fixture (10) an entry opening that enables it to perform (12), ● on the upper fixture (20), the cylindrical element (30) of the test element during the shear test by making contact with the body part and applying a shear load through this part 20 providing, through which the test element (30) passes inside the body and the lower fixture (10) aligned on the same cutting plane with the connection gap (11) on it cutting gap (21) It includes. 25 2. A shear test setup (A) conforming to Claim 1, the feature of which is; different diameters, thicknesses or an alternative test element (30) of the dimensions through the same test setup (A) to enable the sub-fixture in question to be subjected to a shear test in that position. (10) on the connection gap (11) in addition to the body of the test element (30) 30 a second connection that allows it to be inserted by passing it through the part It contains the space (13).
3. A shear test setup (A) conforming to claim 2, characterized by its second connection gap. (13) subjecting the test element placed over (30) to shear load 35 12 In order to provide, an additional cutting gap (21) was added to the said upper fixture (20). and the second connection gap (13) will be aligned on the same cutting plane. It includes a second shear gap (22) structured in this way.
4. A shear test setup (A) conforming to Claim 1, its characteristic being; during the shear test, test 5 to ensure the stable and repeatable positioning of the element (30). so, the connection gap (11) on the lower fixture (10) and the upper fixture (20) the shear gap (21) on the test element (30) to be tested geometric Depending on their characteristics, they come in different widths, different depths, and different cross-sections. It is structured in such a way that it will have its own geometries. 10 5. A shear test setup (A) conforming to Claim 2, characterized by its second connection gap. (13) The test elements placed over (30) can be subjected to shear testing. In order to ensure that the said second connection gap (13) will be tested Depending on the geometric properties of the element (30), different widths, different 15 structured to have depths and different cross-sectional geometries It is the fact that.
6. A shear test setup (A) conforming to claim 3, with the feature of; second shear gap (22) 20 test elements (30) to which shear load will be applied will be subjected to shear test. In order to ensure that it can be held, the second cutting gap (22) is tested Depending on the geometric properties of the test element (30) to be tested, different widths, structured to have different depths and different cross-sectional geometries It is the fact that.
7. A shear test setup (A) conforming to Claim 1, the characteristic of which is; during the shear test Structural integrity and geometric features are maintained under the high shear forces generated. In order to ensure the preservation of sensitivity, the lower fixture (10) and the upper fixture (20) It is structured to be made of a metal material.
8. A shear test setup (A) conforming to Claim 1, its characteristic being that it is tested during the shear test. The upper fixture (20) which applies a shear load to the element (30), test element (30) structuring it to have a higher hardness than its current hardness and this The purpose is to manufacture it from heat-treated hardened steel material.