How Can Piezoelectric Materials Generate Electricity from Walking?

[NAP2626]

Hey I am looking for an example problems that have piezoelectrics generating electricity.

I would like to have and use a simple problem in which a piezoelectric is squeezed to generate electricity. Does anyone know where I can find such problems and solutions?

 

[NAP2626]

I was thinking something a long the lines of;

You have a 1000 N force striking a block of PZT that has a 20 cm by 20 cm area and that has a thickness of 3 cm. How much voltage and power is created.

What you know: Youngs mod, piezoelectric coef, relative permitvity, etc.

Step 1) Calculate change in thickness using
Delta t = (Force * thickness)/(youngs mod *area)

Step 2) with delta t you can figure out strain using
Strain = delta t/t

step 3) With Strain figure out stress, recall we know youngs mod;
Stress = younds mod/ strain

Step 4) D= d*T; piezoelectric coefficent * stress = Columbs/m^2

Step 5) Get charge q: columbs/ m^2 * area (m^2) = charge columbs

Step 6) Capactience; (Relative permit * permit of space)*( Area/ thickness)

now finally Step 7) Voltage: V= Q/C so you take the charge calculate in step 5 and divide it by the materials capacitence calculate in step 6.

Let me know what you guys think or if this is the correct approach. Also how would I calculate the internal resistance of the material so that I can take the voltage use that resistance to caculate current and power.

Any insight or corrections would be great

 

[oswaler]

Piezoelectric materials have the unique ability to convert mechanical energy into electrical energy when subjected to mechanical stress. This phenomenon, known as the piezoelectric effect, has many practical applications. One example of this is in energy harvesting, where piezoelectric materials are used to generate electricity from everyday movements such as walking or even the vibrations of a car engine.

To provide an example problem, let's consider a scenario where a piezoelectric material is placed in a shoe and is subjected to the weight and movement of a person walking. The piezoelectric material is connected to a circuit that includes a light bulb. The goal is to calculate the amount of electricity generated by the piezoelectric material and determine if it is enough to power the light bulb.

We can start by determining the amount of force applied to the piezoelectric material with each step. Let's say the person weighs 150 pounds and takes 10,000 steps in a day. This would result in a total force of 1.5 million pounds being applied to the piezoelectric material.

Next, we need to know the piezoelectric coefficient of the material, which is a measure of how much voltage is generated per unit of pressure. Let's assume this coefficient is 0.1 volts per pound.

Using these values, we can calculate the total voltage generated by the piezoelectric material in a day:

Voltage generated = 1.5 million pounds x 0.1 volts/pound = 150,000 volts

Now, let's assume the light bulb requires 100 volts to turn on. We can determine the number of light bulbs that can be powered by the piezoelectric material:

Number of light bulbs = 150,000 volts / 100 volts = 1,500 light bulbs

This example problem demonstrates how a piezoelectric material can generate electricity from mechanical stress and potentially power everyday devices. It is important to note that the actual values used in this problem are for illustrative purposes only and may vary depending on the specific materials and conditions involved.