Thanks for the very clear explanations. I am curious if you could comment on the Nasa fabric style of lattice unit cell, and the features of that spiral-like sort of design?
Hi Tom, I am not sure about how the Nasa fabric works. It seems more of a meta-material with a negative poisson ratio. It has cells that are connected by flexible struts which allows it to deform in every direction. I think you will have to look at the modelling of metamaterials for the Nasa fabric.
@@MichaelOkereke thanks for pointing me in a productive direction, since I find half the battle for makers (as opposed to academics) is knowing the correct terms to search for! I value your channel as a great source of the principles and underpinning science behind additive manufacturing and materials, and whilst I don't have the technical background to apply everything you share, at the very least I can take away the practical insights and apply them in my design thinking. Thanks again.
Great video, Dr. Michael! I was wondering if you could create a tutorial on frequency analysis (shaker test) for lattice structures. It would be really helpful. Thank you, and God bless you, sir!
@@MichaelOkereke Thank you, sir. I also have another question. Is the homogenization method used in the video Asymptotic or Multi-Scale? I have trouble distinguishing between them.
@@MichaelOkereke Hello Mr. Okereke, I would like to construct the stiffness matrix of an RVE. To do so, I took the RF and divided it by the effective surface (as you did in the video). For the RF, I took a displacement in the X direction and the RF1, RF2, and RF3 from these results. However, I am not getting the same results in my stiffness matrix (it is supposed to be symmetric). So, how can I find the stiffness matrix? Thank you in advance.
Great video! I have one question. Is the compression same to the tension for stress and strain results? Young's modulus and ultimate strength are normally from the tensile test case. But then, compression test case gives the same Young's modulus and ultimate strength with respect to the tensile testing?
Hello @Enidentictok, for the case that I considered here, the tensile and compressive properties should be the same. This is not always the case for most materials - especially polymers where the compressive strength is higher nearly always than the tensile case. It is a well known phenomena and there exists constitutive models for capturing this. For our case in this video, this is not the case.
Hello @Arun, I do think this is possible. It depends on the unit cell, if you can generate an arbitrary shape unit cell, then it is possible to generate the full corresponding lattice. I will need more information for a definite answer.
Could you make a video of LS fea in which top and bottom plates are considered separate rigid bodies rather than merged with LS body. In experiment, top and bottom fixture plates are not part of LS body. Thank you
Hello 3D PRINTech, I chose to model without the rigid plates, as you rightly said, because I wanted to focus on the Unit cell and RVE alone. The rigid plate will impose similar deformation as what I did here. Clearly, for certain simulation scenarios, a separate modelling with rigid plates might be beneficial. I will consider the request and see if I can make a video based on your recommendations. Kind regards.
Hello @etc, thanks for the comment. What sort of variable thickness do you mean here? Is it variable strut thickness or variable structural thickness i.e. changing height of the lattice structure? If you have a reference publication, do share that with me.
Nice one Dr. Okereke...
Great video! Thanks! Can you make a video on calculating bulk modulus of lattice structure.
Great suggestion! I will try and make this video to show you how to do so. Watch this space.
Thanks for the very clear explanations. I am curious if you could comment on the Nasa fabric style of lattice unit cell, and the features of that spiral-like sort of design?
Hi Tom, I am not sure about how the Nasa fabric works. It seems more of a meta-material with a negative poisson ratio. It has cells that are connected by flexible struts which allows it to deform in every direction.
I think you will have to look at the modelling of metamaterials for the Nasa fabric.
@@MichaelOkereke thanks for pointing me in a productive direction, since I find half the battle for makers (as opposed to academics) is knowing the correct terms to search for! I value your channel as a great source of the principles and underpinning science behind additive manufacturing and materials, and whilst I don't have the technical background to apply everything you share, at the very least I can take away the practical insights and apply them in my design thinking. Thanks again.
Glad to help Tom, and good luck!
Great video, Dr. Michael! I was wondering if you could create a tutorial on frequency analysis (shaker test) for lattice structures. It would be really helpful. Thank you, and God bless you, sir!
Great suggestion @Wander! I have not done such frequency analysis before so I might not be able to help you. Good luck with the study.
@@MichaelOkereke Thank you, sir. I also have another question. Is the homogenization method used in the video Asymptotic or Multi-Scale? I have trouble distinguishing between them.
@@wandergabriel4160 it's computational homogenization after the multiscale argument.
@@MichaelOkereke Hello Mr. Okereke,
I would like to construct the stiffness matrix of an RVE. To do so, I took the RF and divided it by the effective surface (as you did in the video). For the RF, I took a displacement in the X direction and the RF1, RF2, and RF3 from these results. However, I am not getting the same results in my stiffness matrix (it is supposed to be symmetric). So, how can I find the stiffness matrix?
Thank you in advance.
Great video! I have one question. Is the compression same to the tension for stress and strain results? Young's modulus and ultimate strength are normally from the tensile test case. But then, compression test case gives the same Young's modulus and ultimate strength with respect to the tensile testing?
Hello @Enidentictok, for the case that I considered here, the tensile and compressive properties should be the same. This is not always the case for most materials - especially polymers where the compressive strength is higher nearly always than the tensile case. It is a well known phenomena and there exists constitutive models for capturing this. For our case in this video, this is not the case.
@@MichaelOkereke Thank you! Could you leave a reference about a constitutive model as you said?
Great video sir. Please do a tutorial for natural fibre reinforced concrete [fibre randomly oriented] Thank you
Hello @Just Cz, good suggestion and something to consider for the future. Cheers!
Great video! Is it possible to generate such a lattice in a arbitrary shape such as a disk etc?
Hello @Arun, I do think this is possible. It depends on the unit cell, if you can generate an arbitrary shape unit cell, then it is possible to generate the full corresponding lattice. I will need more information for a definite answer.
@@MichaelOkereke something like this, th-cam.com/video/LdnoDgXfa6w/w-d-xo.html
Superb Sir
Sir,How can we module BCC Lattice Structre if can do this very thankfully to sir
Yes we can @nimra ishaq, I will make videos about this in future.
Could you make a video of LS fea in which top and bottom plates are considered separate rigid bodies rather than merged with LS body. In experiment, top and bottom fixture plates are not part of LS body. Thank you
Hello 3D PRINTech, I chose to model without the rigid plates, as you rightly said, because I wanted to focus on the Unit cell and RVE alone. The rigid plate will impose similar deformation as what I did here. Clearly, for certain simulation scenarios, a separate modelling with rigid plates might be beneficial. I will consider the request and see if I can make a video based on your recommendations. Kind regards.
@@MichaelOkereke I appreciate it. Thank you.
Can you do one on variable thickness lattice structures please?
Hello @etc, thanks for the comment. What sort of variable thickness do you mean here? Is it variable strut thickness or variable structural thickness i.e. changing height of the lattice structure? If you have a reference publication, do share that with me.