Close this search box.
Characterizing the ...
Clear all

Characterizing the viscoelastic properties of blubber

4 Posts
4 Users
0 Reactions
Posts: 1
Topic starter
New Member
Joined: 12 years ago

Hi All,

I am currently conducting research on whale blubber and hoping for suggestions as to what type of parameters and testing I could focus on to characterize this material. What parameters/tests are people generally interested in when looking to fully characterize a viscoelastic material? Thank you in advance!

3 Replies
Posts: 8
Active Member
Joined: 12 years ago

Your question is vague.

I find it useful to think about the process of characterizing a rubbery material as follows (I will assume no damage will occur in your material for your application):

Step 1: Choose a hyperelastic function. By definition this means that loading and unloading will be along the same path. Thus, finding the material constants for your hyperelastic function (e.x. initial shear modulus) will require that you perform tests (e.x. compression test) at an infinitesimally slow strain rate.

Step 2: Add on a viscoelastic function. Viscoelastic effects will cause the loading to stiffen and the unloading will no longer follow the loading path. You can find the material constants for your viscoelastic function by performing dynamic tests (e.x. Drop tests, DMA).

Step 3: Implement your completed material model into a finite element code. Now you can subject your material to various funky loads at various rates of loading and get good results -- now that your material model is fully characterized, as you say.

In reality, this is all quite complicated.
Thus, Jorgen has created a tool called MCalibration that allows you to choose your material model (i.e. choose your hyperelastic and viscoelastic functions) and then MCalibration will take whatever test data that you have and characterize your chosen model, automatically. Some will fit the data better than others. MCalibration also exports to some of the commercial codes.

Alternatively, you can use the material models that are built-in to your commercial code.

Depending on the kinds of loads (tension? shear?), strain magnitudes, and strain rates that you expect your whale blubber to see in its application will determine the material model that is most appropriate and the kinds of tests and the number of tests that you ought to perform. That information would help experts in the forum (not necessarily me) answer your original question, for example.

Sorry for the longish post, I was on a roll

3 Replies
Posts: 87
Trusted Member
Joined: 14 years ago

afrediens comments are spot on.

Here are my 2 cents:

You can never fully characterize any material but the hope is by applying a few basic loading profiles and curve fitting all those stress-strain curves by a single strain energy potential, the material will behave reasonably well in complex loading. Of course, an appropriate failure criterion must also be chosen and a reasonable factor of safety taken into account. Uniaxial tensile test, compression (confined/unconfined), shear (regular/dual-lap), biaxial are just a few tests that are typically used in characterizing soft tissues. However, without knowing the microstructure, function and the application, the whole process can be off-target. In other words, the blubber may, rarely, if ever undergo compression in reality. So, is compression test really all that necessary to carry out? At what rates does the blubber typically undergo strains? So, at what rates should you conduct your uniaxial tensile test(s)? Should you simply go with hyperelasticity or should you pile on linear viscoelasticity (or quasi-linear or even nonlinear!)? Should you take the Mullins effect (hysteresis) into account?

These questions cant be answered without keeping the function and the overall goals in mind. And, of course, you cant incorporate everything in the first shot. It is prudent to start with the most simple stuff (like isotropic elastic -> bi/tri-linear isotropic elastic -> isotropic hyperelastic -> isotropic hyperelastic and linear viscoelastic -> isotropic hyperelastic and quasi-linear viscoelastic -> anisotropic hyperelastic and quasi-linear viscoelastic and so on.) The first two in the series may be quite inaccurate in characterizing the material but these material models will give you some sort of baseline values to do a sanity check on the results later on.

Posts: 1
New Member
Joined: 12 years ago

Amazing Facts about Vivienne Westwood Shoes

There are designs of high-heeled shoes that you may want to go for now. The Vivienne Westwood shoes collections offer you wide ranges that you surely can soothe your taste. This article reveals some amazing facts you ought to know about [url= ]Vivienne Westwood London[/url]

The Designer

Vivienne Westwood is an English designer of repute that started her collections of designs from the 1980&#8242,s. She has partnered with other top designers like Mellisa to design some of the classy shoes that has made the Vivienne Westwoods brand a house hold name. The brand is fashionable among the modern punk and new wave fashion. Her inspiration and enthusiasm builds up from the inspirations and skills she got working with Mclaren in the 1970&#8242,s. Today, her collections of high heeled shoes and boots have made her outstanding in providing for foot wears suitable for the winter collections.

The Designs

Vivienne Westwood shoes come in various styles and designs. They are peculiar with multiple buckles, bows, laces, and ties placed on a high platform heels. You can find various styles and colors that suit different users ranging from celebrities to the down-to-earth punk enthusiasts. Hence, Popular Celebrities like Naomi Campbell have been spotted wearing this footwear on the runway in the Paris Fashion Week of 2006.

The Online Collections

If you want to have your own collection of Vivienne Westwood shoes then here are list you can find online Lady Dragon II Red Pumps, MAN Seditionary Boot Black and Shoes Black, Leather Pirate Yellow boot, Roman 3-Atrap shoes, Suede Pirate boot, and lots of other exquisite collections that can add color and style to you lifestyle.

They come in various colors and sizes that fit your foot. You can order for any shoes or boots of your choice.

You can shop your collection today online from the Vivienne Westwoods website at discounted prices. There are other websites where you can also buy collections of these shoes. Once you search for[url= ]Vivienne Westwood Sale [/url]

, you sure will get displays of vendors. So, go for your classic high-heeled shoes and boots from this unique designer today