A constrained free-fall frangible cap crash test system and method

Abstract

This invention discloses a constrained free-fall type fragile cover impact test system and method, belonging to the field of mechanical equipment performance testing. It includes: a support base to ensure the guide frame is perpendicular to the ground; an impact projectile suspended within the guide frame, with an adjustable height; the guide frame connected to the fragile cover by fasteners, simulating the constraint and guidance of the launch box / tube on the impact projectile, allowing the projectile to impact the fragile cover in free fall without jamming or eccentricity; and a sensor for measuring the impact force. This invention replaces the constraint and guidance of the launch box (tube) on the projectile with the constraint and guidance of the guide frame, utilizes the principle of free fall to represent the velocity of the projectile impacting the fragile cover, and measures the impact force that breaks the fragile cover using a sensor. The structure is simple, significantly reducing testing costs; it offers good guidance and centering accuracy, preventing projectile eccentricity and accurately simulating actual working conditions; the fragile cover is easy to assemble and disassemble, resulting in high testing efficiency.

Description

Technical Field

[0001] This invention belongs to the field of mechanical equipment performance testing, and more specifically, relates to a constrained free-fall type fragile cover impact test system and method. Background Technology

[0002] Fragile caps are a crucial technological product for rapid response and convenient launch, significantly impacting the rapid launch capability of stored, launched, and transported launch products. Since the warhead tip directly impacts the fragile cap during launch, its hardness and impact opening force must meet stringent requirements, especially for more delicate warheads. This necessitates a certain degree of fragility. These caps are typically made of rigid polyurethane foam, and to control the breakage state, weak grooves are machined into their surface, resulting in some uncertainty in their breakage performance.

[0003] Therefore, to shorten the development time of the cover, improve the understanding of the product's performance capabilities, and ensure its performance stability, it is necessary to conduct impact and pass tests to ensure that its performance meets the product's design requirements. However, due to considerations of time, manufacturing, cost, and safety, the impact and pass tests cannot be performed directly using a launch box (tube); specialized equipment is required.

[0004] Currently, among the existing technology verification products in China, there are devices specifically designed for impact testing, such as CN203011233U and CN107271298B. However, their structures are relatively complex, especially the guidance and restraint structures, which differ significantly from actual operating conditions. Due to the complexity of their structures, their testing costs are also relatively high. Furthermore, they focus primarily on impact capability, i.e., only using the warhead tip for impact testing, with less consideration given to the impact of the cylindrical section in the middle of the missile body on the canopy, indicating insufficient attention to the missile's maneuverability. Verification of the fragility of the canopy's mooring capability is also often inadequate. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a constrained free-fall type fragile cover impact test system and method, which aims to solve the problems of complex structure and high cost of existing test equipment.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a constrained free-fall type fragile cover impact test system, comprising: a support base, an impact projectile, a guide frame, and a sensor; one end of the support base is connected to the guide frame via fasteners, and the other end is in stable contact with the ground to ensure that the guide frame is perpendicular to the ground; the impact projectile is suspended inside the guide frame, and its height is adjustable; the lower end face of the guide frame is connected to the fragile cover via fasteners to simulate the constraint and guidance effect of the launch box / launch tube on the impact projectile, so that the impact projectile impacts the fragile cover in a free-fall manner, and no jamming or eccentricity occurs during the impact process; the sensor is used to measure the impact force of the impact projectile breaking the fragile cover.

[0007] Preferably, the guide frame includes: a plurality of guide posts and a plurality of frame rings; the plurality of guide posts are parallel to the free fall path of the impact projectile; the plurality of frame rings are perpendicular to the free fall path of the impact projectile; the plurality of guide posts are welded to the inner side of the plurality of frame rings and are in clearance fit with the impact projectile.

[0008] It should be noted that the guide post of the present invention is welded to the inner side of the frame ring, which has a guiding and restraining effect on the impact warhead.

[0009] Preferably, the sensor is built into the impact projectile, which further includes: a lifting ring body, a sensor mounting section, a projectile compartment section, a projectile cone section, a connecting shaft, and an impact projectile tip; the lifting ring body, sensor, connecting shaft, and impact projectile tip are coaxial; one end of the lifting ring body is used for lifting with a lifting device, and the other end is screwed to the sensor; the sensor is threaded between the lifting ring body and the connecting shaft; the connecting shaft is installed between the sensor and the impact projectile tip via external threads, and is located within the sensor mounting section, the projectile compartment section, and the projectile cone section, all with gaps; the sensor mounting section is bolted between the lifting ring body and the projectile compartment section; one end of the projectile compartment section is bolted to the sensor mounting section, and the other end is welded to the projectile cone section.

[0010] It should be noted that: 1) This invention incorporates a highly realistic impact tip, cone section, and warhead section within the impact warhead. During testing, it can verify not only the breakage of the warhead upon impact with the cover but also the mooring capability of the fragmented cover. It allows for clear observation of the actual unfolding of the fragile mooring cover after being impacted by the cone section and warhead section, thus enhancing the verification capability of the testing equipment and verifying the mooring capability of the cover. 2) Preferably, the spacing between the guide frame rings is smaller than the height of the warhead warhead's warhead section. This enhances the strength and rigidity of the guide frame, increases guiding capability, reduces the risk of jamming, provides good guiding and centering performance, and ensures the constraint form closely resembles the actual constraint state. 3) The built-in sensor within the impact warhead improves test accuracy.

[0011] Preferably, the spacing between the rings of the guide frame is less than the height of the spring column section.

[0012] It should be noted that the present invention preferably uses the above-described structure, which provides corresponding unfolding space in all directions, so as not to affect the breakage of the fragile cover and to facilitate intuitive observation of the unfolding process.

[0013] Preferably, the support base is in the shape of an isosceles trapezoid, and its height is greater than that of the fragile cover.

[0014] It should be noted that the present invention preferably uses the above-described structure to increase the stability of the support base in contact with the ground.

[0015] Preferably, the support base is assembled and welded from several channel steels and square tubes.

[0016] It should be noted that the present invention has a simple structure, fewer parts, and lower cost, which can greatly reduce testing costs and verification costs.

[0017] Preferably, the circumferential installation position of the fragile cover satisfies the following condition: the breaking and unfolding direction of the four broken cover petals pre-divided by the weak groove is within the four "four"-shaped frames of the support base.

[0018] To achieve the above objectives, in a second aspect, the present invention provides a constrained free-fall type fragile cover impact test method, comprising: constructing a test system as described in the first aspect; adjusting the hoisting height of the impact projectile such that the velocity of the impact projectile when it impacts the fragile cover in free fall is equivalent to the velocity of the projectile when it impacts the fragile cover; releasing the impact projectile and measuring the impact force of the impact projectile impacting the fragile cover.

[0019] In summary, the technical solutions conceived by this invention have the following beneficial effects compared with the prior art:

[0020] This invention provides a constrained free-fall fragile cover impact test system and method. It replaces the constraint and guidance of the launch box (tube) on the projectile with the constraint and guidance of a guide frame. The free-fall principle is used to simulate the velocity of the projectile impacting the fragile cover, and sensors measure the impact force that breaks the cover. This invention has a simple structure, few parts, and low cost, significantly reducing testing expenses. It offers good guidance and centering accuracy, preventing projectile eccentricity and accurately simulating actual working conditions. The fragile cover is easy to assemble and disassemble, resulting in high testing efficiency. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a constrained free-fall type fragile cover impact test system provided in an embodiment of the present invention.

[0022] Figure 2 A cross-sectional view of an impact projectile provided in an embodiment of the present invention.

[0023] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0024] 1-Impacting warhead; 2-Guide frame; 3-Test fragile cover; 4-Support base; 1.1-Lifting ring body; 1.2-Sensor; 1.3-Sensor mounting section; 1.4-Warhead column section; 1.5-Warhead cone section; 1.6-Connecting shaft; 1.7-Impacting warhead tip. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0026] This invention provides a constrained free-fall fragile cover impact test system, comprising: a support base, an impact projectile, a guide frame, and a sensor; one end of the support base is connected to the guide frame via fasteners, and the other end is in stable contact with the ground to ensure that the guide frame is perpendicular to the ground; the impact projectile is suspended inside the guide frame, and its height is adjustable for simulating actual working conditions for pre-test impact; the lower end face of the guide frame is connected to the fragile cover via fasteners to simulate the constraint and guidance effect of the launch box / launch tube on the impact projectile, so that the impact projectile impacts the fragile cover in a free-fall manner, and the impact process does not cause jamming or eccentricity; the sensor is used to measure the impact force of the impact projectile breaking the fragile cover.

[0027] Preferably, the guide frame includes: a plurality of guide posts and a plurality of frame rings; the plurality of guide posts are parallel to the free fall path of the impact projectile; the plurality of frame rings are perpendicular to the free fall path of the impact projectile; the plurality of guide posts are welded to the inner side of the plurality of frame rings and are in clearance fit with the impact projectile.

[0028] The guide columns can be evenly distributed or determined according to the actual constraint state of the missile inside the box (tube).

[0029] Preferably, the sensor is built into the impact projectile, which further includes: a lifting ring body, a sensor mounting section, a projectile compartment section, a projectile cone section, a connecting shaft, and an impact projectile tip; the lifting ring body, sensor, connecting shaft, and impact projectile tip are coaxial; one end of the lifting ring body is used for lifting with a lifting device, and the other end is screwed to the sensor; the sensor is threaded between the lifting ring body and the connecting shaft; the connecting shaft is installed between the sensor and the impact projectile tip via external threads, and is located within the sensor mounting section, the projectile compartment section, and the projectile cone section, all with gaps; the sensor mounting section is bolted between the lifting ring body and the projectile compartment section; one end of the projectile compartment section is bolted to the sensor mounting section, and the other end is welded to the projectile cone section.

[0030] Preferably, the spacing between the rings of the guide frame is less than the height of the spring column section.

[0031] Preferably, the support base is in the shape of an isosceles trapezoid, and its height is greater than that of the fragile cover.

[0032] Preferably, the support base is assembled and welded from several channel steels and square tubes.

[0033] Preferably, the circumferential installation position of the fragile cover satisfies the following condition: the breaking and unfolding direction of the four broken cover petals pre-divided by the weak groove is within the four "four"-shaped frames of the support base.

[0034] This invention provides a constrained free-fall type fragile cover impact test method, comprising: constructing the test system as described above; adjusting the hoisting height of the impact projectile, wherein the height is such that the velocity of the impact projectile when it impacts the fragile cover in free fall is equivalent to the velocity of the projectile when it impacts the fragile cover; releasing the impact projectile and measuring the impact force of the impact projectile impacting the fragile cover.

[0035] During the test, the support base (4) is placed in the test site, and several sandbags are placed inside it. The height of the sandbags should not interfere with the segmentation of the cover. On the one hand, it helps to tighten the fixing device, and on the other hand, it buffers and protects the impact projectile from directly hitting the rigid surface and protects the internal sensor from overloading. Lubricant is applied to the guide column to reduce friction. The suspension rope is cut and the impact projectile (1) falls through the guide frame (2) to hit the test fragile cover (3) to complete the test.

[0036] Example

[0037] like Figure 1 As shown, in this embodiment, the constrained free-fall fragile cover impact test system consists of an impact projectile 1, a guide frame 2, a test fragile cover 3, and a support base 4. The guide frame 2 is installed on the upper part of the support base 4 and is vertical, used to simulate the constraint and guidance effect of the launch box (cylinder) on the projectile, ensuring that the projectile does not jam or become eccentric during impact with the test fragile cover. The test fragile cover 3 is installed at the lower part of the guide frame 2, ensuring that the test fragile cover 3 and the guide frame 2 are horizontal. The impact projectile 1 is suspended inside the guide frame 2, ensuring that the distance between its impact tip and the impact surface of the fragile cover 3 reaches a predetermined height. The frame ring in the guide frame 2 can be used as a reference for the predetermined height.

[0038] The support base 4 is assembled and welded from several channel steels and square tubes, and the whole is in the shape of an isosceles trapezoid. Eight base plates are welded to the bottom surface to ensure stable contact with the ground.

[0039] The guide frame 2 consists of four guide posts, five frame rings, four welded pillars, and a cover mounting plate. The guide posts are vertical relative to the cover mounting plate, parallel to the impact warhead's descent path. The four guide posts are welded into the five frame rings. The frame rings are welded to the cover mounting plate via the welded pillars, and the lower surface of the cover mounting plate is connected and fixed to the assembly base via bolts. The four guide posts of the guide frame and the impact warhead's projectile section have a clearance fit; lubricant is applied to the guide posts during testing to reduce friction.

[0040] The test fragile cover 3 is installed under the guide frame 2. The test fragile cover typically has two intersecting weak grooves to facilitate the breakage and fragmentation of the cover. During installation, the direction of fragmentation can be referenced. Its circumferential installation position should ensure that the breakage and unfolding directions of the four pre-divided fragments by the weak grooves are within the four "four"-shaped frames of the support base 4. This ensures that there is no structural obstruction in the unfolding direction of the fragments, allowing for easy observation of the entire process of the cover breaking through.

[0041] like Figure 2 As shown, the impact warhead 1 consists of a lifting ring body 1.1, a sensor 1.2, a sensor mounting section 1.3, a projectile compartment section 1.4, a warhead cone section 1.5, a connecting shaft 1.6, and an impact warhead tip 1.7. The sensor 1.2, lifting ring body 1.1, connecting shaft 1.6, and impact warhead tip 1.7 are installed coaxially, with the sensor 1.2 located between the lifting ring body 1.1 and the connecting shaft 1.6. The upper end of the sensor mounting section 1.3 is screwed to the lifting ring body 1.1, and the lower end is screwed to the projectile compartment section 1.4. The projectile compartment section 1.4 is welded to the lower part of the warhead cone section 1.5.

[0042] The connecting shaft 1.6 is located within the sensor mounting section 1.3, the projectile compartment section 1.4, and the projectile cone section 1.5, with a 2.5mm gap between each. Therefore, the mass of the upper end of the sensor 1.2 can be considered the sum of the lifting ring 1.1, the sensor mounting section 1.3, the projectile compartment section 1.4, and the projectile cone section 1.5, while the mass of the lower end is the sum of the connecting shaft 1.6 and the impact force of the projectile tip 1.7. The measurement is the impact force of the lower end impacting the projectile tip 1.7 onto the cover. The data measured by the sensor can be converted into impact force data using the principle of free fall. The connecting shaft 1.6 is lubricated during installation and undergoes heat treatment during machining to prevent impacts from causing structural damage and bending, which could affect the sensor's measurement results.

[0043] The impact projectile 1 comprises a highly realistic impact tip 1.7, a projectile section 1.4, and a projectile cone section 1.5. It not only verifies the breaking force of the fragile cover upon impact with the impact tip 1.7, but also observes the fragile cover's ability to be pushed open and split into pieces by the projectile section 1.4 and the projectile cone section 1.5. This verifies not only the fragile cover's impact and passage capability but also the tethering capability of the tethered cover, expanding the application scenarios of the test. Furthermore, the impact tip 1.7 is the part that directly impacts the projectile; its surface may have scratches and damage after the test. Therefore, it is made with a threaded connection to enhance replaceability and maintainability. Before the test, its surface can be touched up with paint and repaired. The damage to its surface can also characterize the damage and impact of the tested fragile cover 3 on the projectile body, enriching the reference results of the test.

[0044] The working process of the test system described in this embodiment is as follows: The equipment and the test fragile cover are installed. Based on the impact and passability test requirements, the required height to actually launch from the box (tube) is calculated using the free-fall formula and the velocity equivalence method. Then, the impact warhead is hoisted to the corresponding position using a steel wire rope. The steel wire rope is then cut, and the impact warhead falls freely under the guidance and constraint of the guide frame, finally breaking through and passing through the fragile cover.

[0045] The term "velocity equivalence" here refers to the velocity being the same as the actual velocity of the warhead when it impacts the cover after exiting the box (tube).

[0046] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A constrained free-fall type fragile lid impact test system, characterized in that, include: Support base, impact warhead, guide frame, and sensors; The support base is connected to the guide frame to ensure that the guide frame is perpendicular to the ground; The impact warhead is suspended inside the guide frame, and its height is adjustable; The lower end face of the guide frame is connected to the fragile cover by fasteners to simulate the constraint and guidance effect of the launch box / launch tube on the impact warhead, so that the impact warhead impacts the fragile cover in a free fall manner, and no jamming or eccentricity occurs during the impact process. The sensor is used to measure the impact force of the impact projectile breaking through the fragile cover; The guide frame includes: multiple guide posts and multiple frame rings; The multiple guide posts are parallel to the free fall path of the impact warhead; The multiple frame rings are perpendicular to the free fall path of the impacting warhead; The multiple guide posts are welded to the inner side of the multiple frame rings and are gap-fitted with the impact warhead.

2. The system as described in claim 1, characterized in that, The sensor is built into the impact warhead, which also includes: a lifting ring body, a sensor mounting section, a projectile compartment section, a projectile cone section, a connecting shaft, and an impact warhead tip; The lifting ring, sensor, connecting shaft, and impact tip are in a coaxial position; One end of the lifting ring is used for lifting and hoisting with the lifting device, and the other end is screwed to the sensor; The sensor is connected to the lifting ring body and the connecting shaft by a threaded connection; The connecting shaft is installed between the sensor and the impact projectile tip via an external thread, and is located within the sensor mounting section, the projectile column section, and the projectile cone section, all of which have gaps. The sensor mounting section is bolted between the lifting ring body and the spring column compartment section; One end of the projectile section is bolted to the sensor mounting section, and the other end is welded to the projectile cone section.

3. The system as described in claim 2, characterized in that, The spacing between the rings of the guide frame is less than the height of the ejector section.

4. The system as described in claim 1, characterized in that, The support base is in the shape of an isosceles trapezoid, and its height is greater than that of the fragile cover.

5. The system as described in claim 4, characterized in that, The support base is assembled and welded from several channel steels and square tubes.

6. The system as described in claim 4, characterized in that, The circumferential installation position of the fragile cover should meet the following requirement: the breakage and unfolding direction of the four broken cover petals pre-divided by the weak groove should be within the four "four"-shaped frames of the support base.

7. A constrained free-fall type fragile lid impact test method, characterized in that, include: Construct the test system as described in any one of claims 1 to 6; Adjust the hoisting height of the impact warhead so that the velocity of the impact warhead when it hits the fragile cover in free fall is equivalent to the velocity of the warhead when it hits the fragile cover. Release the impact warhead and measure the impact force of the impact warhead striking the fragile cover.

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