can someone help me with the following issue. I need a method for transforming mechanical work into electrical energy without using piezoelectricity. I have such kind of mechanical forces (like on the picture in the link) and I want to transform this mechanical force into electrical energy.
To make the hint from Rodrigo more specific, you could take a look at high impedance electromagnetic headphones. It is basically a coil that magnetizes a piece of iron when a current is run through the wires. This magnet will then attract a metal sheet or a diaphragm just like the one in your picture.
Now you could think about reversing the process, and directly connect the diaphragm to a permanent magnet inside the coil. Now a movement will create a current in your coil wire.
Well, I'm not an electrical engineer, but I think this can help:
"Although the various conversion devices operate on similar principles, their structures depend on their function. Devices for measurement and control are frequently referred to as transducers; they generally operate under linear input-output conditions and with relatively small signals. The many examples include microphones, pickups, sensors, and loudspeakers. A second category of devices encompasses force-producing devices and includes solenoids, relays, and electromagnets. A third category includes continuous energy-conversion equipment such as motors and generators."
Source: FITZGERALD, A. E. Electric Machinery, 6 ed. McGraw Hill
I believe the best way you can convert mechanical work into electrical energy is through an electric generator. An electric generator works through electromagnetic inductance which is the property of a conductor by which a change in current in the conductor "induces" (creates) a voltage in both the conductor itself and in any nearby conductors.
There are many options of electric generators, but I believe the more common are the dynamo, which produces direct current through the use of a commuter, and the alternator, which produces alternating current. In general, the use of a commuter makes the dynamo more expensive and therefore the alternator is more common in the industry due to efficiency, reliability and cost reasons, since it's cheaper to transform alternating current into direct current through power rectification devices.
Here is a reasonable source for you to know more: https://en.wikipedia.org/wiki/Electric_generator
I hope it helps!