# Scientific Laws for Engineering Materials

Tags:
1. Mar 5, 2015

### sawer

I have a conceptual question.

There is a law in science for every phenomenon in nature, like gravity or electric field.

But also there are laws for springs or capacitors etc... I mean the engineering materials that are produced by engineering processes, not can be found in the nature itself. Is there a name for those types of laws, the name that indicates the difference from other scientific laws?

2. Mar 5, 2015

### Staff: Mentor

The fundamental physical laws apply to all materials. The relationships that describe the macroscopic behavior of each specific material in various physical situations are empirical physical property equations developed from experimental data. These are called physical property relationships. Examples are Ohm's law (resistance), Hooke's law (both 1D springs and 3D solids, Young's modulus, Poisson ratio), heat capacity, thermal conductivity, etc.

Chet

3. Mar 5, 2015

### sawer

Physical property relationships of what?
Engineering materials.

In engineering mechanics lesson for engineering students, formulas for translational, rotational, fluid, electrical, thermal systems are given in a table with an analogy.

I am asking about these formulas. These formulas are related with engineering systems and materials, they are not like gravity and electromagnetism... Is there a special name for those formulas? How can we name it?

4. Mar 5, 2015

### Staff: Mentor

Yes.
Translational and rotational follow directly from Newton's second law, which applies to all materials. So they are fundamental.

Physical Property Relationships

Fluids: Newtonian fluid constitutive equation in tensorial form....Physical property = viscosity

Electrical:
Ohm's law.......Physical property = resistance
Capacitors......Capacitance
Inductors,,,,,,,,,Inductance

Solid Mechanics: Hooke's law in tensorial form, Physical properties = Young's modulus, Poisson ratio

Heat Transfer: Heat conduction equation, property = thermal conductivity

Mass Transfer: Fick's law, property = diffusion coefficient

Flow in Porous Media: Darcy's law, property = hydraulic permeability

etc., etc.

Do you get the idea now?

Chet

Last edited: Mar 5, 2015
5. Mar 5, 2015

### sawer

Almost. Thank you very much. Just one question.
OK. You said these are "fundamental".
So what can we name for those? Derived? (Derived may be too simple) Derived of/from what?
This is all I was trying to asking.

6. Mar 5, 2015

### Staff: Mentor

I don't think they have an official name. I call them either physical property relationships or idealized material behavior models. You can call them what you want. The important point is that you understand that they are models of material behavior rather than fundamental laws of physics.

Chet