RU2372510C1 - Solid-fuel rocket engine housing made from composite material - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: solid-fuel rocket engine housing made from composite material consists of a pressure all-wound cocoon-type shell, the second cocoon shell and flat cables of the onboard cable system. Middle part of cables is arranged in the space between cocoons, and end cable parts from the space between cocoons to connectors and the connectors themselves - outside at bottoms of pressure shell; at that, connectors are fixed on bottoms. Lengths of end cable parts are bigger than lengths of meridional arches under them on the bottoms, and differences between lengths of end cable parts and lengths of meridional arches corresponding to them under them comply with the ratios protected with this invention.

EFFECT: improving operating reliability of wound cables in solid-fuel rocket engine housing made from composite material owing to eliminating tension of metal cable wires.

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Description

The invention relates to mechanical engineering, and in particular to solid-fuel rocket engine bodies (solid propellant rocket engines) made from composite material (KM), and can be used to create solid-fuel rocket engines.

From the technical literature, a solid propellant rocket motor enclosure is known that contains a power unidirectional sheath of the “cocoon” type, a sheath of the second cocoon, and flat cables of the onboard cable network, the middle part of which is located in the inter-window space, and their connectors are mounted externally on the bottoms of the power sheath (see. “Rocket Engine Designs” on solid fuel ”, under the general editorship of the correspondent of the Russian Academy of Sciences, doctor of technical sciences, professor LN Lavrov. - M.: Mechanical Engineering, 1993, p. 54, Fig. 2.1).

When fastening cable connectors on the bottoms, when the length of the cable ends corresponds to the lengths of the meridians of the bottoms under the cable, at internal pressure due to the tension of the power sheath, shear forces arise in the places where the connectors are attached to the bottoms and tensile forces in the metal wires. This can lead to their rupture (or deformation), as well as to the separation of wires from the connectors (or separation of the connectors from the bottoms).

An object of the invention is to increase the reliability of cables by reducing tensile forces in the cable wires.

The technical result is achieved in that in the housing of a solid propellant rocket engine made of composite material containing a solid unibody power sheath of the cocoon type, a sheath of the second cocoon and flat cables of the onboard cable network, the middle part of which is located in the inter-window space, and the cable end parts are from the inter-window space to the connectors and the connectors themselves are externally on the bottoms of the power shell, while the connectors are fixed on the bottoms, the length of the cable ends is longer than the lengths of the meridional arcs below them on the bottoms, and the differences between the lengths of the end parts of the cable and the lengths of the corresponding meridional arcs under them must satisfy the relations:

Here:

L _1k , L _2k - the lengths of the end parts of the cable on the front and rear bottoms, respectively;

L _1e , L _2e - the length of the meridional arcs under the cables along the front and rear bottoms;

Index? L _1e, ΔL _2d - extension of meridional arcs under the cables of the front and rear ends, respectively;

ΔL _c - the extension of the cylindrical part of the housing.

Figure 1 shows a cross section of a solid-propellant housing containing a power sheath 1, a cylindrical sheath of a second "cocoon" 2, a flat cable of an onboard cable network 3 with connectors 4. Figure 2 shows the cable location zone: the middle part of the cable in the inter-window space 5, end parts of the cable on the front bottom 6 and on the rear bottom 7 with connectors 4, when the lengths of the cable ends correspond to the arcs of the bottom meridians. Figure 3 presents the parts of the cable 5, 6, 7 in a stretched position under the action of internal pressure. Figure 4 shows the proposed initial location of the cable ends 6 and 7 with lengths L _1k and L _2k over the corresponding arcs of meridians 8, 9, whose lengths L _1d and L _{2d are} less than the lengths L _1k and L _2k . Figure 5 presents the change in the shape of the end parts of the cable 6 and 7 of the proposed design under the action of internal pressure.

Under the action of internal pressure, the tension of the power shell of the body occurs. When fixing the cable connectors 4 (figure 2) on the bottoms so that the total cable length (the sum of the lengths of the cable sections 5, 6, 7) is equal to the initial length of the meridian of the power sheath under the cable, the cable extension ΔL _k under pressure (Fig. 3 ) corresponds to the elongation meridian structural envelope body between the cable connectors ΔL _CO, which in turn is the sum of the extensions on the bottoms of portions of meridians _1e ΔL, ΔL ΔL cylinder _2g and _i:

ΔL _k = ΔL _CO = ΔL _1d + ΔL _c + ΔL _2d .

Given the high deformability of the CM, the elongation between the places of fastening of the cable connectors can be significant. When this occurs, tensile forces in the metal wires and shear forces in the places of attachment of the connectors 4 to the bottoms of the power shell 1 (Fig.3). This can lead to rupture or deformation of the wires, as well as to the separation of wires from the connectors 4, or the separation of the connectors 4 from the bottoms of the power shell 1.

In the proposed design, the fastening of the cable connectors 4 is made in such a way that the arcs of the bottom meridians under the cables L _1e and L _{2d are} less than the lengths of the cable sections L _1k and L _2k (Fig. 4). Under the action of pressure due to the straightening of the end sections of the cable 6, 7 (Fig. 5), the tensile forces of the wires are reduced.

With the appropriate choice of the lengths of the meridional arcs when the power sheath is elongated, tensile forces in the wires of the cable end sections can be completely eliminated. However, in this case, in the middle part of the cable 5 (Fig. 5), tensile forces of the wires can occur under pressure. This is due to the fact that the sheath of the middle part of the cable 5 is stretched, the wires are displaced relative to the sheath and due to friction between them, they are stretched. In the absence of tensile forces in the wires of the cable ends, the maximum value of the force occurs in the middle of the cylindrical part of the power sheath (fixed point). In this case, the force depends on the length of the cylindrical part L _c (Fig. 4) and on the coefficient of friction. With increasing length L _u force increases. If the wires can move freely relative to the cable sheath, then the tension forces of the wires along the entire length of the cable can be eliminated. But if tensile forces of the wires of the end parts arise, then the maximum tensile force of the wires of the middle part of the cable increases. In this regard, the task is reduced to determining the lengths of the meridional arcs under the cable ends, which eliminate the tension of the wires of the cable ends and minimize the tensile forces in the wires of its middle part, regardless of the value of the friction coefficient.

If the displacement of the wires relative to the cable sheath is absent (high coefficient of friction), then to eliminate the tension of the wires in the end parts, it is enough that the difference between the lengths L _1k , L _{2k of the} end parts of the cable 6, 7 (Fig. 4) and lengths L _1e , L _2e meridional arcs beneath 8, 9 elongations were not less than these arcs _1d ΔL, ΔL _2d (5) at a pressure of:

However, with a minimum (close to zero) coefficient of friction of the wires relative to the cable sheath, in order to exclude tension forces, one should also take into account the extension of the cylindrical part of the power sheath. Given that the fixed point when the wires are displaced is in the middle of the cylindrical part, half the elongation ΔL _{c of the} cylindrical part of the power shell should be included in the right-hand sides of the inequalities (Fig. 5):

When this ratio is fulfilled, there are no tensile forces of the wires in the cable ends 6, 7 (Fig. 5), and therefore there is no load on the cable connectors 4. If the wires can freely move relative to the cable sheath, then the tension forces of the wires along the entire length of the cable are absent.

However, in the presence of friction (regardless of the value of the coefficient of friction), the tensile strength of the wires in the middle part of the cable 5 (Fig. 5) is significantly less than in the design shown in Fig. 2, since in the end parts 6, 7, and therefore and at the borders of the middle part of the cable 5 with the end parts 6, 7 (Fig. 5), there are no tensile forces of the wires.

Thus, the use of the invention will eliminate the tension of the metal wires of the cable in the end parts, significantly reduce the tensile forces of the passages in the middle part of the cable, and, ultimately, eliminate possible wire breaks, as well as the separation of wires from the connectors (or the separation of the connectors from the bottoms) when extending the power shell under the action of internal pressure.

This invention improves the reliability of the coiled cables in the housing of the solid propellant rocket composite material.

Claims (1)

A solid-propellant rocket engine housing made of composite material, containing a power unidirectional sheath of the cocoon type, a sheath of the second cocoon and flat cables of the onboard cable network, the middle part of which is located in the inter-window space, and the cable ends from the inter-window space to the connectors and the connectors themselves are externally the bottoms of the power shell, while the connectors are fixed on the bottoms, characterized in that the lengths of the cable ends are longer than the lengths of the meridional arcs below them on the bottoms, and the differences between the lengths end parts of the cable and the lengths of the corresponding meridional arcs under them must satisfy the relations:
L _1k -L _1d ≥ΔL _1d + 0.5ΔL _c ;
L _2k -L _2d ≥ΔL _2d + 0,5ΔL _c ,
where L _1k , L _2k - the lengths of the end parts of the cable on the front and rear bottoms, respectively;
L _1e , L _2e - the lengths of the meridional arcs under the cables along the front and rear bottoms, respectively;
Index? L _1e, ΔL _2d - extension of meridional arcs under the cables of the front and rear ends, respectively;
ΔL _c - the extension of the cylindrical part of the housing.

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