Technical Field of the Invention

The invention relates to a method for increasing the strength of a fixed or moving structure under an impact force during a finite time interval.

State-of-the-art

Existing fixed or moving structures subjected to an impact force during a finite time interval are often subject to destruction represented by large permanent deformation or rupture. To prevent this destruction, either a simple reinforcement of the structure subjected to a force load is used or pre-formed parts of the structure to be destroyed are used in the event of a force load. These parts of the structure absorb into their permanent deformation the energy brought by the force load, which would otherwise cause the destruction of the structure itself. In each case of an impact force, this part of the structure to be destroyed will be destroyed, which means that the overall structure will not be further usable.

The aim of the present invention is a method and apparatus for reusing a structure subjected to an impact force without destruction and for increasing the strength of a fixed or moving structure under impact force during a finite time interval so that the structure has higher resistance to force loading and there was no permanent deformation (destruction).

Subject Matter of the Invention

The subject matter of the method for increasing the strength of a structure connected to the frame and subjected to an impact force is that the structure is divided into at least two parts, a support part and an impact part, of which the support part joins the frame and between the support part and the impact part, inserts an actuator to dampen the load force acting on the impact section. An inserted impact part is separated from the impact part, and an actuator for damping the load force acting on the impact part is inserted directly and I or via the inserted impact part between the support part and the impact part.

The subject matter of the construction with increased impact strength associated with the frame consists in that it consists of at least two parts comprising a support part connected to the frame and at least one impact part, an actuator being arranged between the support part and the impact part(s). The impact part consists of at least two parts comprising at least one impact part and at least one inserted impact part arranged between the support part and the impact part, between the support part and the impact part(s) and the inserted impact part(s) and between the inserted actuators are arranged actuators.

The support part is connected to the at least one impact part and/or the inserted impact part by means of a rotational joint or a sliding guide. The inserted impact part is connected to the at least one impact part and / or another inserted impact part by means of a rotational joint or a sliding guide.

Overview of Figures in Drawings

The attached figures schematically show a device for increasing the strength of a fixed or moving structure under an impact force during a finite time interval, where

Figures 1 to 4 depict one of the basic embodiments of the device,

Figures 5 to 19 depict alternative embodiments of the device

Examples of Embodiments of the Invention

Fig. 1 shows a conventional arrangement where the fixed structure 11 is attached to the frame 10 and loaded by a load force 12 representing an impact force, which means that the load force 12 acts for a limited finite time interval. For example, an impact force is created by the impact of a moving obj ect on a fixed structure 11 , the flexibility of the fixed structure 11 creates a braking force equal to the load force 12, and the fixed structure 11 accumulates kinetic energy of the moving object until it stops. The fixed structure 11 in such an arrangement often ruptures under the action of load force 12. The impact force can thus only act once, because the structure will be destroyed. The force load in Fig. 1 represents the compressive load, but in the following it will be generalized to the tensile, bending, shear and torque loads.

Fig. 2 shows a solution which prevents the fixed structure 11 of Fig. 1 from rupture. The fixed structure 11 is divided into an impact part 1 and a support part 2 attached to the frame 10. The impact part 1 and the support part 2 are connected by an actuator 3. Acting of the load force 12, the impact part 1 will start moving towards the support part 2 and the force of the actuator 3 will act against this movement so that the load force 12 is at or below the limit of the force which would cause the impact part 1 or the support part 2 to rupture, that is, to its destruction. The impact force can thus act repeatedly, as the structure will not be destroyed.

Actuator 3 can be an active drive that exerts a computer-controlled force. Such an actuator is a hydraulic cylinder, a linear electric motor, a piezo actuator, an electrodynamic (voice coile), a controlled damper, a controlled spring, etc. The requirement for it is especially to achieve high acceleration and speed. Such an actuator can be a damper, a spring with a constant or non-progressively increasing force depending on the deformation, etc. The active actuator is able to return the structure to its original shape after absorbing the impact force. A passive actuator is also able to do this if it also contains a spring with positive stiffness. Passive dampers can also be disposable made of plastic deformable bodies of the mandrel and hole type, which slide into each other and thus develop a damping force.

In Fig. 3, the solution from Fig. 2 is supplemented by a sensor 6 for measuring the relative movement of the impact part 1 and the support part 2. It can be a mutual position sensor, e.g. distance, mutual speed or acceleration, or a force sensor between the impact part 1 and support part 2. This sensor 6 serves to control the acting force (effect) of the actuator 3 as an active element.

Fig. 4 shows how an impact force is created by a load force 12. Each force is given by the interaction of material objects. The impact force is generated in such a way that a moving body 14, which moves at a speed vO, comes into contact with the body of the impact part 1.

The resistance of the impact part 1 braking the movement of the moving body 14 corresponds to the magnitude of the impact force by load force 12.

If the movement of the moving body 14 is stopped during time T, then approximately its deceleration of magnitude -vO/T and at the same time the acceleration of the impact part 1 of magnitude vO/T takes place. Then (a is the acceleration, v is the velocity, s is the position of the moving body 14 and identically of the impact part 1, t is the time) a=dv/dt = -vO/T v=vO - vO/T t (1) v=ds/dt -vO -vO/T t s=vO t - vO/T t ^A 2/2

Since the movement takes place until zero speed for the time T, the resulting path of the body of the impact part 1 is equal to s = vO T/2. This space is necessary between the bodies of the impact part 1 and the support part 2 to stop the movement of the impact part 1.

The equations of motion apply to the forces (Fact is the force of the actuator 3, ml is the mass of the impact part 1, m is the mass of the moving body 14)

F12 - Fakt = ml a (2) m a = F12

After substituting from (1) to (2) we get m vO/T - Fakt = ml a = -ml vO/T (3) (m+ml)vO/T - Fakt The impact force by load force 12 and the applied force Fakt of the actuator 3 must be less than the destructive force Fdest, which would cause the body of the impact part 1 or the support part 2 to rupture.

F12 < Fdest (4)

Fakt < Fdest

After substituting from (2) and (3) to (4) we get

F12 = m a < Fdest m vO/T < Fdest T > m vOZFdest (5)

Fakt = (m+ml)vO/T < Fdest T > (m+ml)vO/Fdest ml < Fdest T/vO - m (6)

The last relation shows that the mass of the body of the impact part 1 has certain limits of its size. This is also due to the fact that each body is flexible and its compression as a spring leads to an increase in internal forces. Therefore, it is necessary to divide the body of the impact part 1 into sub-bodies and by the actuators 3 between them to brake and dissipate the energy of the impact force load with the load force 12.

In Fig. 5, the body of the fixed structure is divided into three sub-bodies and several actuators 3, namely into the impact part 1, the inserted impact part 21 and the support part 2 connected by the actuators 3. The division can continue as required into a plurality of inserted impact parts 21 and a support part 2. Here it is shown that several actuators 3 can act simultaneously between the impact part 1 and the inserted impact part 21.

Fig. 6 shows a variant of the solution from Fig. 2, where the impact part 1 is connected to the support part 2 next to the actuator 3 also by a rotational joint 4. The mutual mobility of the impact part 1 and the support part 2 is maintained and is given by the rotation on which the actuator 3 acts.

Fig. 7 shows an alternative variant of the solution from Fig. 6, where the impact part 1 is connected to the support part 2 next to the actuator 3 also by a sliding guide 5. The mutual mobility of the impact part 1 and the support part 2 is maintained and is given by sliding (translation) on which the actuator 3 acts. Fig. 8 shows a branched structure of the inserted impact parts 21 interconnected by a series of actuators 3 and the rotational joints 4 and the sliding guides 5. Several impact forces with load forces 12 act on the impact part 1 at the same time.

Fig. 9 shows another variant of the branched structure of the inserted impact parts 21 interconnected by a series of actuators 3 and rotational joints 4. The load force 12 is here the tensile force.

Fig. 10 shows a case where the impact part 1 is divided into a plurality of parallel impact parts 1 connected by rotational joints 4 so as to be distributed with respect to a plurality of individual simultaneous impact forces loaded by the load forces 12.

The concurrent impact forces with the load forces 12 according to Fig. 10 arise in such a way that one impact load force 12 acts on a larger area of the impact part 1, where due to the remoteness of the parts of the impact part 1 which are subjected to a load force 12 from another part of impact part 1 not loaded by the load force 12, their mutual deformation occurred and as a result the impact part 1 cracks. Therefore, the impact part 1 is divided into several parallel impact parts 1 in principle approximately in the direction perpendicular to the acting load forces 12, which eliminates by their mutual mobility the problem of mutual stress on larger parts of the loaded impact part 1.

Fig. 11 shows a case similar to Fig. 10, in which the impact part 1 is divided into a plurality of parallel impact parts 1 connected here by sliding guides 5 so as to be distributed against a plurality of impact force by load forces 12.

Fig. 12 shows a case similar to Fig. 10 and 11. Here, the impact part 1 is divided on the one hand into a plurality of parallel impact parts 1 in principle approximately in a direction perpendicular to the acting load forces 12, which eliminates by their mutual movability the problem of their mutual stress on a larger part of the loaded impact part 1, and on the one hand on several inserted impact parts 21 in the direction of the acting load forces 12. Mutual mobility of the divided impact parts 1 then allows functionality even if the load force 12 is not simultaneous and/or the load force 12 does not act on all distributed impact parts 1, but will only act on some. In addition, Fig. 12 shows the possibility of combining the rotational joints 4 and the sliding guides 5 between the divided impact parts 1 and the inserted impact parts 21.

Fig. 13 shows a case similar to Fig. 1, where the fixed structure 11 embedded in the frame 10 is loaded by a load force 12 representing an impact force which causes the bending stress of the structure. Fig. 14 shows a solution similar to Fig. 2, which prevents the fixed structure 11 of Fig. 13 from rupture. The fixed structure 11 is divided into an impact part 1 and a support part 2 both embedded in the frame 10. In both structures 1 and 2 bending flexibility is assumed. The impact part 1 and the support part 2 are connected by an actuator 3. By the action of the load force 12 the impact part 1 deforms flexibly and begins to move towards the support part 2, which also deforms and the force of the actuator 3 will act against this movement so that the impact force the load force 12 will be at or below the limit of the force which would cause the impact part 1 or the support part 2 to rupture.

Fig. 15 shows another solution of the case of Fig. 13. Instead of solving the bending stress of the structure by the impact force of load force 12 by means of the division of the structure according to Fig. 14, another division of the structure is used. Bending stress is solved by shear stress. The impact part 1 and the support part 2 are connected by a sliding guide 5 and an actuator 3, which acts between the impact part 1 and the support part 2.

Fig. 16 shows a case of a conventional arrangement, similar to Fig.l wherein the fixed structure 11 embedded in the frame 10 is loaded by a torque (pair of load forces) 12 representing the impact torque load which causes the torsional stress of the fixed structure 11.

Fig. 17 shows a solution similar to Fig. 2, which prevents the fixed structure 11 of Fig. 16 from rupture. The fixed structure 11 is divided into an impact part 1 and a support part 2 embedded in the frame 10. In both structures 1 and 2, assumes torsional compliance. The impact part 1 and the support part 2 are connected by an actuator 3 capable of generating a torque. By the action of the load moment 12 the impact part 1 torsionally deforms and starts to rotate with respect to the support part 2, which also torsionally deforms and against this movement the torque of the actuator 3 will act so that the load force 12 in the form of torque will be at or below the limit of the magnitude of the torque which would cause the impact part 1 or the support part 2 to rupture.

It is suitable to divide the fixed structure 11 into as many impact parts 1 and inserted impact parts 21 that the braking forces of the actuators 3 allow the impact parts 1 and the inserted impact parts 21 to move at the rate of increase of the load force 12 without actuator forces 3 causing the impact parts 1 or the inserted impact parts 21 or the support part 2 to rupture.

In all the cases described, the frame 10 can be a moving part of a heavy-duty structure with large mass. Its inertial mass (force) then replaces the frame. An example is a car crash into an obstacle or a mutual crash of cars. Another example is the impact of a projectile into a movable structure. This is schematically shown in Fig. 18, where the support part 2 still has a large mass even after the impact part 1 has been separated. Here, the support part 2 can represent the body of the car and the impact part 1 its bumper or the front part of the body. Another example is the torsional load of a rotating shaft.

Another example of a moving part of a heavy-duty structure with large mass representing a frame is shown in Fig. 19. The rotating rotor is movably connected to the frame 10 by bearings 13. The rotor is flexurally loaded by an impact load force 12. To withstand this load, it is divided into the impact part 1 and the support part 2. The impact part 1 and the support part 2 are connected by actuators 3. The bending flexibility of the impact part 1 is assumed to allow its movement with the actuators 3. The large inertial mass (force) of the support part 2 then replaces the frame.

Actuators can be controlled drives, but also passive dampers or dampers connected to springs. Constant force springs are an advantage. The actuators are computer controlled.

All the variants described above can be combined with one another in various ways.