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Re: paper on composite fatigue

Thu, 2018-02-01 17:27

In reply to Wenbin, I remain disappointed you don't want to try

Hi Mike,

Don't want to interrupt your discussion with Wenbin, but couldn't help jumping in.  

I can assure you there are many more than 10 people that work on composite fatigue.  It's just that these difficult problems are not of interest in academia.  As I have said several times, editors will need to expand their list of contacts to find these people.

Another observation is that if a paper has not garnered much interest in several years maybe the results are not of interest per se.  The publication process is supposed to weed out uninteresting results from the literature.  In that case, why burden the editorial process further?

I'm sure those who need those results have already downloaded the paper from arxiv and used the results.  It's just that you don't see them citing it.  So one has to be clear whether the goal is the dissemination of knowledge or improving one's citation count.

Enough discussion for now; need to get back to debugging :)

-- Biswajit

Bioarxiv: A more recent incarnation of arxiv

Thu, 2018-02-01 17:18

In reply to Mike, original post was to

Hi Wenbin,

If you can get hold of the funds, I'd suggest you try to expand cdmHub to include more fields of mechanics.  An example of a very successful recent model is bioarxiv  You could contact the leeaders of that effort to find out how they approached the problem and what issues they ran into.

-- Biswajit

an example from real life -- I just received

Thu, 2018-02-01 16:56

In reply to Some ideas for a possible new journal

I am trying to resuscitate a journal with a friend, and he writes me how hard it is just 5 minutes ago.  Obviously I remove all the names.

So this is just an example from real life.


Dear Professor Ciavarella, 


thank you, I am trying t do my best. You see, when the former Editor was retired the journal was in no single indexing database and looked pretty bad - issue were 1 year late and there was 1 or 2 issues per year, depending on how many papers arrived in the previous year (no paper was rejected). Nobody wanted to take over the journal. I dared to do that and it was starting with 2014. The web-page changed (but we had to use the OJS system, which I do not prefer very much, but this is what the yyyyyyyyyyyy - the publisher, could afford), the Editorial Board, the editorial policies were completely new... In 201? we got the SCOPUS and WOS indexing (starting with 201?), among a number of other, smaller indexing databases, which are simply not important. Now, all those guys who never paid attention to the journal would like to take it over, and to offer publications to their friends. But the people in charge at the KKKKKKKKK how it was and how it is now and they insist I must continue. 


The objective remains the SCIe index and the number of citations in 2018 and 2019 will be decisive (Clarivate Analytics will start finalizing the evaluation in August 2019). We look quite good so far with citations in 2016 and 2017, we just need to keep that trend. I am very happy there are some very prolific authors in this issue, particularly you. And, as I have already said 1000 times, whoever supports the journal with citations will always have the open door for publications and the Editorial Board will be reshuffled when the evaluation is finished. Those authors will also be offered to become members of the EB.


So, now you know a little bit more about the history and development of XXXXX in the next years. 


Best regards,


Wenbin, I remain disappointed you don't want to try

Thu, 2018-02-01 16:25

In reply to Some ideas for a possible new journal

my test.  You are in composites, you are working on a proposals in composites fatigue, and you haven't had any comment on my Kassapoglou paper.  I know this is a little off-topic, but not so much after all.  Your technology will not change the rule of the game:  you need to find time to read the paper in details, as Editor, to find good reviewers (and on that subject in general there are only 10 or so in the world, and most of them are not willing to do the job).

So, for me the discussion is getting boring.  You don't want to comment yourself on the Kassapoloug's arxiv paper, not even to tell me why it failed to pass the traditional system of journals, then I loose interest in your proposal, and I wish you good luck.

Re: More on Mike's questions

Thu, 2018-02-01 16:21

In reply to Biswajit, I am even more confused after your replies.

I've been out of the publishing game for many years now and don't read IJSS any longer.  So I don't know who the current editors are.  But I was mildly amused by my experience; and I didn't find it surprising given my experiences in departmental faculty meetings.

I think a starting point would be to actively expand the pool of reviewers (whether it is for a new journal or for an existing one).  A repository that specializes in mechanics would be helpful for people like me (and I hope people interested in knowledge and understanding in general).  But that will need money and resources; and some creative thinking by younger people.  Keep in mind that arxiv is now more than 20 years old.

-- Biswajit

Biswajit, I am even more confused after your replies.

Thu, 2018-02-01 16:03

In reply to Some ideas for a possible new journal

Since I am not sure which system would solve the many issues you raise.

The editor of IJSS would not be happy of your statement, it is offensive.  Since I know one of them, it must be the other, the one in US, who is the same who asked me to be out of the editorial board?

Re: On Mike's three questions about publication

Thu, 2018-02-01 15:43

In reply to better way of publication


1a) Cheaper:  Cheaper for whom?  I have to pay USD 50 to read a typical paper which may or may not have any information that's useful.  So it's definitely not cheaper for me.  Also, many academics appear to be bombared by e-mail nowadays and requests for papers have recently started to go unanswered.  So the old approach of asking for papers does not work any longer. 

1b) Editors' hard work:  The failure to find reviewers indicates that editors are not actually working that hard to find people.  They just look at the list of references and send out requests to people instead to exapnding their networks to a larger group of non-academics.  What makes you think that non-academics are not knowledgable just because they don't have the incentive to publish as frequently as academics.  In my experience, particularly in engineering, many non-academics are much more knowledgable about their fields than academics.

1c) Typesetters improving papers:  I do all the typesetting of my papers myself and design figures and tables myself too.  Elsevier's typesetters are well known for destroying equations and one has to go and recheck everything twice to make sure things are OK.  Maybe typesetters help improve Nature papers, but definitely not regular journal papers.

2) Faster:  I sent a paper to IJSS a few years ago and the editor sat on it for two years and finally sent it back saying it was unsuitable for the journal.  In the mean time, that person published a very similar paper in the same journal.  No, mechanics journals are not fast enough unless the authors and editors know each other.  Not all of us have the resources or the time to create such a network by visiting numerous conferences each year and publishing numerous papers.

3) Peer review:  I've had many peer reviews where it was clear that the reviewer didn't know what they were talking about (or had given up reading after the first few pages).  The only way to fix this problem is to broaden the pool of reviewers by creating connections with more academics and researchers outside academia.  Every review that I do takes at least a day and I don't get any reputation points for doing that, but I still review papers because I get to know about the latest thinking in the subfield.

Keep in mind that for every faculty member at a university, there are at least 50 PhDs who are working in industry.  It's your job as academics to keep in tough with these students of yours and increase the pool of reviewers.  And I'm sure academics can easily come up with more creative solutions instead of complaining about quality (after all the quality of your students reflects your quality) of reviewers available.

-- Biswajit

Re: People don't take arxiv seriously?

Thu, 2018-02-01 15:23

In reply to Mike, original post was to


I agree with you on that.  In mathematics and some subfield of physics, arxiv submissions are taken very seriously.  That's probably because results can be verified by readers and, if found inaccurate, papers have been known to be withdrawn from the repository.  The same is true of computer science, e.g., all major deep learninng papers are published on arxiv first.  That allows people to know what's being done and allows for all sorts of views to be heard, instead of just academic views.  

Personally, I've seen a huge difference in the attitude of reviewers between when I was in academia and when I was in industry.  Reviewers tend to dismiss work that's done inside industry; and I think that reflects poorly on mechanics researchers. It also removes feedback to researchers on what's considered important in industry and where there are gaps in knowledge.

-- Biswajit

Response to your questions

Thu, 2018-02-01 15:21

In reply to Nice work!

Dear Jiawei,

Thank you for your interest in our work and your stimulating questions. I have answered them below:

1. When the actuator lift weights, the part composed of elastomer membrane and soft electrode is stretchable, does that compromise the actuation?

Answer: In the case of the donut actuators, a very soft membrane can hinder actuation under heavy loads, as the liquid dielectric tends to bulge the side walls of the soft shell instead of translating the force upwards to lift the weight. For this reason, we used a stiffer elastomer, namely PDMS, instead of other softer silicone based products, such as Ecoflex.

2.The voltage applied determines how heavy the weight can lift. But for lifting heavy weight, your voltage is very high, does that hinder the practical application?

Answer: It is important to note that HASEL actuators are not strictly voltage dependent. The electrostatic stress generated within the shell is proportional to the electric field squared and dielectric constant of the solid-liquid composite dielectric. In our initial work, we used relatively thick membranes (on the order of 1mm) to construct the actuators, as these membranes were easier to handle and sufficient for proof of concept work. These thick membranes resulted in the need for rather high voltages to generate the necessary electric fields to trigger actuation. The voltages used in our initial work are indeed too high for practical applications; however, some strategies for reducing the operating voltage include increasing the dielectric constant of the composite structure or decreasing the distance between the electrodes by utilizing thinner membranes for the shell. Currently, we have designs which operate at 10 times less voltage while still generating high forces, making the electronics practical and the actuators extremely useful!

3. When the elastomer membrane contacts, does the high voltage cause electric breakdown of the elastomer?

Answer: Typical operation of HASEL actuators does not cause breakdown of the composite dielectric structure. That is, we primarily do not use electric fields which are higher than the dielectric strength of the composite dielectric (though, if we did, the actuators could self-heal from the breakdown). There is indeed a large change in the electric field after a pull-in transition; however, the maximum field is still below the dielectric strength of the composite and so breakdown does not occur. Additionally, there is always a layer of solid dielectric between the two electrodes, which prevents the electrodes from shorting during operation.

4. What is the maximum liquid you can put in the actuator? Is there any limitation? 

Answer: The content of liquid dielectric is far from optimized. We tested a few different oil contents to roughly determine what worked well for our demonstrations, but did not perform a rigorous analysis to optimize the fill amount. It’s important to note that as the amount of liquid inside the elastomer shell is increased, the distance between the electrodes in the relaxed state also increases. Therefore, the voltage required to generate the electric field necessary to trigger actuation also increases drastically. If the applied voltage is held constant throughout the pull-in transition, the electric field at the end of the transition may exceed the dielectric strength of the material and result in dielectric breakdown.



better way of publication

Thu, 2018-02-01 14:52

In reply to Some ideas for a possible new journal

Then I am confused.  I still do not understand what is better


1) is it cheaper?   But the little money given to editors for hard work, and for typesetters to improve papers, although a small part of the big margin Elsevier and other companies make, is needed to ensure high quality


2) is it faster?  Most journals are fast these days


3) do I get a more proper peer review?   Why?  Most journals even of high reputation, have troubles to find high quality reviewers, and I know many scientists of even high level (not perhaps of high ethical standards) who review papers in few seconds, saying this is wrong, because I did it much better 2 years ago.


So please recap which one is better.

Thank you!

Thu, 2018-02-01 14:38

In reply to Great job, Christoph!

Dear Zhigang:  Thank you for your positive comment -- this means a lot to me and my students!


Our work on HASEL artificial muscles synergizes different areas I have studied during my PhD and postdoc, and our papers benefit from all the things I have learned from my academic advisors. My ambitious aim when starting my own lab in Boulder was to invent a new class of artificial muscles that enables a next-generation of soft robots that are high-speed, versatile and electrically powered, thereby avoiding the issues that arise from the use of compressors and valves in soft pneumatic actuators:

1) I have started to appreciate the wide range of possible geometries of soft fluidic actuators when working as a postdoc with George Whitesides at Harvard. Using liquid dielectrics as a hydraulic fluid, HASEL actuators inherit the versatility of soft fluidic actuators.

2) Even before I started my PhD with Siegfried Bauer, he introduced me to the fascinating world of dielectric elastomer actuators (DEAs). I was immediately convinced that this type of actuator is extremely promising, when seeing the speed, efficiency and ability to capacitively self-sense deformation. Just like dielectric elastomer actuators, HASEL artificial muscles are driven by Maxwell stress, and thus inherit the high-performance and the capacitive self-sensing abilities of DEAs. In contrast to DEAs, HASELs use a liquid dielectric, which self-heals after dielectric breakdown, and thus avoid central issues of DEAs, such as catastrophic dielectric breakdown and electrical aging. For this exact reason, industry widely uses liquid dielectrics in HV transformers.

3) Zhigang, when working together with you as a postdoc, I have started to realize that the nonlinearities and instabilities in soft active materials are a feature, and not a problem. Donut HASELs undergo a safe electromechanical instability to reach large deformations. I am absolutely certain that the mechanics community will very soon find new types of electromechanical instabilities in various designs of HASEL actuators. Additionally, HASEL actuators benefit from the unique properties of stretchable, transparent ionic conductors, a topic we introduced together in 2013.


GEO, standing for Gel, Oil, and Elastomer is without a doubt an incredibly interesting combination of materials, that might have applications far beyond the field of soft actuators. I am looking forward to seeing what the Suo group comes up with in this area! My lab has been working on HASEL actuators since more than two years, and we had central results ready more than a year ago. It is always a gamble when aiming to publish in top journals such as Science or Nature, as these outlets require top quality stories, figures, videos and writing -- all of which takes a lot of time and increases the chances that other groups publish the idea first. I am incredibly proud of my team of first-rate students, who pushed the initial papers introducing HASELs over the finish line with creativity, dedication and hard work. 4 of them -- Eric Acome, Nicholas Kellaris, Timothy Morrissey, Shane K. Mitchell -- have helped me put together the journal club post and will be discussing with us here.

When thinking about industrial applications of HASEL artificial muscles, we realized that the fundamental principles do not depend on elastomers and conductive gels. In our Science Robotics paper on Peano-HASEL actuators, we introduce a materials system with thin polymer films and evaporated metal layers. This materials system is amendable to large scale industrial fabrication, and it does not depend on highly stretchable elastomers or conductive gels. Depending on the specific application, HASELs can be built from a wide variety of different materials.


Zhigang, thank you for your question on liquid dielectrics. While being widely used in the high voltage industry, there is a surprisingly small number of academic papers available on the topic of self-healing in liquid dielectrics. A while back I wanted to better understand the fundamentals of dielectric breakdown and looked for good literature; initially I focused on solid dielectrics, but then found work from the Research Laboratory of Electronics (RLE) at MIT that opened my eyes about the benefits of liquid dielectrics and the rich physics of electrical breakdown: "Mechanisms Behind Positive Streamers and Their Distinct Propagation Modes in Transformer Oil" by Professor Markus Zahn and colleagues. Here is a link:



HASEL actuators solve important issues, but they open up just as many new questions, challenges and opportunities. In our journal club post, we mention a few areas we look forward to working on together with the mechanics, materials, and robotics communities!


Very Inspiring Idea

Thu, 2018-02-01 14:10

In reply to Some ideas for a possible new journal

This is a very interesting idea. Mechanical engineering and mechanics is a very closed door discipline compared to computer science. It will not be an exaggeration to say that the whole open source movement is at the forefront of the rapid progress of computer science. 

Mike, original post was to

Thu, 2018-02-01 14:04

In reply to Some ideas for a possible new journal

Mike, original post was to seek suggestions from the community to come up with a better way of publication. cdmHUB has not implemented my ideas yet. Currently it can serve as a Composites arXiv with review capability. It expose you to a focused community with the possibility to provide feedback on the same site, comparing to arXiv. Researchers in some fields do take arXiv seriously. Somebody paid serious attention to award Grigori Perelman a Fields Medal. 

I have difficulty to see the connection of reviewing your paper with my original suggested ideas. 

Biswajit, composites can

Thu, 2018-02-01 13:50

In reply to Re: Composite fatigue paper

Biswajit, composites can fatigue and we are working a project entitled multiscale fatigue damage of composites right now. Composite fatigue life is much longer than metals though for many applications, that might cause the conclusion that composites do not fatigue. 

Dear Biswajit, Thanks a lot

Thu, 2018-02-01 13:47

In reply to Re: cdmHUB speed

Dear Biswajit, Thanks a lot for your feedback. We are in the process to move cdmHUB to AWS, hoping it will be faster internationally. We did not notice its slowing down at home in US. 


Re: Composite fatigue paper

Thu, 2018-02-01 13:39

In reply to speaking of composite materials,...

I started posting papers on arXiv in the early 2000s but have found that not too many mechanics people read arXiv papers (or cite them).  That's probably because of lack of awareness.  A dedicated server for mechanics papers would help a bit (people have to search in condensed matter physics/mathematics/computer science on arxiv for mechanics papers).

I've heard many "experts" on composites in NZ say that there is no fatigue in polymer composites.  Maybe that's why you don't get reviewers?   Or you may have annoyed a few people and will have to wait until they retire?

-- Biswajit

Re: cdmHUB speed

Thu, 2018-02-01 13:33

In reply to I agree that more important

It's been a while, but I recall that the website took a while to load.  The scalability is determined by the capacity of the server to accept a large number of users simultaneously and the efficiency of the server side software.  I can access most commercial sites worldwide at high speeds.  It's academic sites that turn out to have speed bottlenecks.  On the positive side, I can at least access your site; unlike the Luxembourg (Bordas) site. iMechanica is also relatively slow.

-- Biswajit


but why would I want to get additional reviews if later I go

Thu, 2018-02-01 13:22

In reply to Some ideas for a possible new journal

for a proper journal?

Just today, I finished a big review paper with 35 or so authors which took us endless discussions and even personal attacks -- it was extremely difficult task.   One of the authors was extremely agressive and made 12 pages of "internal review" which took us ages to answer and converge, DESPITE the external standard reviewer asked only for MINOR review.

So in my case, why would I want to submit to your system, if the paper is already on ArXiv for everyone to see it --- but nobody takes it for serious unless is peer reviewed?  Why would I send it to your other system which supposedly makes peer review, and how you convince reviewers to work for a non high reputation journal?

I get dozens of emails a day to review papers from low class journals, which I don't even reply to. 

If you want your system to provide external reviews for people to improve their papers, then ArXiv is good enough.  I can share it to many places, like I did already, and people usually read it, and few of them comment to me.

Yes, I was hoping to make instead another experiment:  if you could review that particular paper on imechanica for me, and see if anybody takes this discussion for serious.  I promise you, it is a good experiment, because the paper is quite critical and you will have hard time to find good reviewers, who make good reviews.

But I am sure you don't want to avoid this "test" --- try!

Wonderful work!

Thu, 2018-02-01 13:21

In reply to Journal Club for February 2018: HASEL artificial muscles for high-speed, electrically powered, self-healing soft robots

Hi, Christoph, Thanks for such a wonderful and inspiring work.

Naturally, muscle contains water and can self-heal. Previous artificial muscle (DEA) mimics functions of muscle, but suffers from electric breakdown. Whereas synthesizing self-healing dielectric elastomer could be an awkward alternative for common mechanical engineers, using liquid dielectric to engender self-healing ability for artificial muscle is simple yet effective. This is really a brilliant work.

The opportunities and challenges section is already very comprehensive, and will lead to many follow-up researches across multiple disciplines.

One particular issue about the practical usage of this device: the hydrogel electrodes are exposed. This may cause several challenges: 1. Whereas hydrogels can retain water with dissolved hygroscopic salts, the water content fluctuates with the ambient humidity. Does the fluctuation of water content (i.e. resistance) of hydrogels affect the device performance? 2. The hydrogel electrodes may contact with other materials, and short circuit might happen if the materials are conductive. 3. Using hydrogel makes the overall device transparent. But the device cannot work in water environment.  Have you found potential solution for this issue?


Thank you.

Yes, you can send it to a

Thu, 2018-02-01 13:08

In reply to Some ideas for a possible new journal

Yes, you can send it to a proper journal later and you only give us the rights to display it (like what you did with arXiv). I can invite experts in composite fatige damage to review your paper. Others who have a cdmHUB account can also review it. The review comments are public.

You signup a free account, then, click Resources->Contribute, select Publications. then you follow the rest of the steps, by putting title, abstracts, and tags, then upload the pdf as an attachment. My admin will approve your submission.

Can you tell me what you want to achieve with your experiment? To see whether somebody would like to review your paper and give you some feedback for improving the paper so that you can make it ready for journal publication or to test whether I can get somebody to review your paper anonyously? 


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