titanium in skis

[nigelc]

I have just spent a couple of weeks shopping for new skis for my wife, trying and comparing different types of skis from different manufacturers. I noticed that a few high end skis are boasting titanium innards. Do any other forum members know what this is all about? is it a metal laminate like the titanal in metal carving boards and there for the same purpose(s). If so what advantage does it offer over the aluminium laminate?

[tex1230]

it's the same - metal has been used in skis for 20+ years IIRC, mostly as a dampening layer.

titanium / aluminum / titanal...all do the same to varying degrees.

[bobdea]

I have just spent a couple of weeks shopping for new skis for my wife, trying and comparing different types of skis from different manufacturers. I noticed that a few high end skis are boasting titanium innards. Do any other forum members know what this is all about? is it a metal laminate like the titanal in metal carving boards and there for the same purpose(s). If so what advantage does it offer over the aluminium laminate?

depends on the ski, most are pretty similar to what snowboard companies are doing now. the construction of my metal coiler looks just like race skis have since the 80s for example.

atomic was and probably still is doing their "titanium tube" gimmick skis which is a different construction. funny though, that construction never made it into the race stock SG and DH models....... should tell you something right there....

[nigelc]

So what does titanium have to offer that aluminium doesn't? It is very pricey compared to Aluminium.

[bjvircks]

it has an exceptional strength to weight ratio and so is very desireable in high performance structures.

[nigelc]

if it was only strength to weight then kevlar, carbon, spectra, PBO or boron fibre would be better.

[bjvircks]

what the hell do I know... I just do this stuff for a living.

[nigelc]

My apologies I am not looking to directly contradict you even if I came across that way. My statement should have been phrased as a question. Essentially I guess the expression "strength" is not specific enough - are we talking stiffness, tensile strength, toughness etc. My engineering is limited to some composite structures in a marine context, where mostly we are concerned with panel stiffness. Pure tensile strength is sometimes of concern in rigs, where PBO is used for rigging

[nigelc]

here is a table/spreadsheet showing strength to weight numbers:

http://numsum.com/spreadsheet/show/18451

so back to my point that there must be another reason for titanium.

[kieran]

the only use my limited imagination can conceive for (actual) titanium in skis would be to reinforce stress points or impact zones. so as an edge liner, or where bindings would be mounted. massive return in strength for nominal mass increase.

i'd have thought (and am probably wrong) that titanium (not titanal) was too rigid to be used as a laminate layer.

[bjvircks]

while various composite fibers have wonderful raw tensile strength, they are just fibers. They need to be incorporated into fabrics or wound on mandrils in very carfully oriented fashion to make use of their strength. If they are used 'wrong' they can be very weak and depend too much on the consolidating epoxy or polyester resins used to bind individual fibers into a unified structure. Imagine a fabric with fibers woven in the X and Y directions. If you pull along the X-X direction... its as strong as the fibers. If you pull in the Y-Y direction... same thing, as strong as the fibers. Now lets say you pull 'corner to corner'. The fabric deforms greatly in a parallelograming fashion and exhibits no significant resistance to deformation... no strength. To help with this issue fabricators will do cross weave layups in order to get strength tailored to the need of the application. This addresses the 'in-plane' properties. Don't get me started on complex structural layups.

Metals generally demonstrate uniform properties in all directions which make then 'better' in certain applications. Sure, the strength to weight ratio may be lower, but the overall cost to benefit balance for implementing a given function may point to metals instead of composites. Recent (last couple decades) has yielded great advances in making structural elements in deep, complex shapes. But these advances have been incremental in nature as we learn more and increase our understanding and fabrication sophistication.. (this generalization is not intended to address boats, which have been using glass/polyester composites for quites a while)

However, this completely ignors the 'gimmic factor' of using fake-tech to market overly expensive toys to people with more dollars than sense.

[nigelc]

Most of the boat composites I am interested in are carbon/nomex/carbon sandwich. Glass composites was a long time ago. I do see the occasional aluminium honeycomb core, or some pvc foam (like some old rossignol boards) on some cheaper layups. Also many different orientations of fibres to deal with the differrent stresses including often gluing unidirectional fibres in specific places to cope with rig loads. I haven't done an analysis of skis but I would have thought the stresses were relatively simple. From what you are saying I guess you think that titanium is just a gimmick with little or no real justification over aluminium/titanal. Shame. I thought we might be seeing a whole new generation of titanium boards

[KingCrimson]

while various composite fibers have wonderful raw tensile strength, they are just fibers. They need to be incorporated into fabrics or wound on mandrils in very carfully oriented fashion to make use of their strength. If they are used 'wrong' they can be very weak and depend too much on the consolidating epoxy or polyester resins used to bind individual fibers into a unified structure. Imagine a fabric with fibers woven in the X and Y directions. If you pull along the X-X direction... its as strong as the fibers. If you pull in the Y-Y direction... same thing, as strong as the fibers. Now lets say you pull 'corner to corner'. The fabric deforms greatly in a parallelograming fashion and exhibits no significant resistance to deformation... no strength. To help with this issue fabricators will do cross weave layups in order to get strength tailored to the need of the application. This addresses the 'in-plane' properties. Don't get me started on complex structural layups.

Metals generally demonstrate uniform properties in all directions which make then 'better' in certain applications. Sure, the strength to weight ratio may be lower, but the overall cost to benefit balance for implementing a given function may point to metals instead of composites. Recent (last couple decades) has yielded great advances in making structural elements in deep, complex shapes. But these advances have been incremental in nature as we learn more and increase our understanding and fabrication sophistication.. (this generalization is not intended to address boats, which have been using glass/polyester composites for quites a while)

However, this completely ignors the 'gimmic factor' of using fake-tech to market overly expensive toys to people with more dollars than sense.

BJ hit it on the head here. Bruce explained it to me like this:

Corner to corner, torsional stiffness is paramount.

Metal acts like a membrane, and can't stretch (as much), but it will flex all day. It's ideal for skis and snowboards.

I think in early boards, the metal stretched in the middle, and went "slack" and delaminated. Or in the other order. I have no idea. Of the early boards I've seen, they delam underfoot quite a lot.

[nigelc]

my understanding is that the reason early metal boards delaminated is that it is very hard to stick anything to a non-absorbent surface. The epoxy will not soak in so there is an issue with bond failure in shear. What titanal offers is an efective chemical etching of the surface of the aluminium sheet to allow a much better bond, hence no delam. As for metal not stretching, it is far stretchier than most fibres. The justification for metal laminates that I have seen on these pages - quite reasonably - is that the metal laminate has a very different natural frequency to the composite and so performs some dampening of vibration. I had assumed when looking at titanium skis that this would be why such a very expensive metal with a strength to weight not much better than Aluminium would be used. Perhaps it has far superior dampening characteristics. Titanium certainly is better with fatigue.

[KingCrimson]

I just assume that there is more to the delaming than adhesives, because they specifically delam underfoot in my experience.

It may be stretchier, but a single strand of fiber does not run corner-to-corner on a snowboard. The epoxy between the fibers DOES stretch.

If you had 2 braided carbon fiber cables running in an X pattern, this would more properly utilize the tensile strength and lack of ductility in the material.

I'm not aware of the angles in the triax weave that alpine builders use, but from seeing carbon fiber on my Coiler, it is not steep enough to allow a single fiber to run corner-to-corner.

[nigelc]

triaxial cloth is at o, +60,-60 degrees, while double bias is at plus and minus 45 degrees.

[scrapster]

This caught my eye when I bought new skis last year--for the first time in 20 years. In many of metal models that I saw the metal layer was not flat (as it is in contemporary alpine snowboards) but was folded in complex ways either longitudinally or laterally (Elan). I would think this adds considerable stiffness, not just dampening?

[nigelc]

i guess that makes more sense. Putting some of the material in shear rather than pure tension or compression. I had not considered thatthe metal was not just a flat sheet. Could the longer path for vibrations also affect the dampening?

[Donek]

To my knowledge, the actual use of titanium in skis is nothing more than marketing people getting it wrong or playing off the titanal name. Titanal has no titanium in it, but ski manufacturers using it will frequently call that line a titanium line or something similar. My guess is that these skis you are looking at have titanal in them, not titanium. Don't trust the salesman; read the web site or literature very carefully.

Triax fabrics can come in many different angles. The most common fiberglass triax in the snowboard industry is 0 and +- 45. At one time there was a 0 and +-22.5 available. A 0 and +-60 will mimic the in plane isotropic behavior of a metal laminate (such as titanal). We are using such a carbon laminate in a new construction for freeride boards this season. In plane isotropic laminates can be generated with 3 or more fiber orientations all spaced equally in equal weight/densities. For the non engineer, isotropic mean the behavior is the same in all directions. In plane refers to the plane of the laminate. It would of course really only have the strength of the binder or resin in stresses perpendicular to that plane.

[nigelc]

To my knowledge, the actual use of titanium in skis is nothing more than marketing people getting it wrong or playing off the titanal name.

Thanks for the insight Sean. I strongly suspected that marketing was the primary reason and could see no justification for titanium as such. I am always prepared to be surprised however.

I have always wondered, sometimes here in writing, why the behaviour of metal for torsion control could not be achieved with properly oriented fibres. I have always been told that the Titanal contributes considerably more than simple torsional strength.

[Donek]

Thanks for the insight Sean. I strongly suspected that marketing was the primary reason and could see no justification for titanium as such. I am always prepared to be surprised however.

I have always wondered, sometimes here in writing, why the behaviour of metal for torsion control could not be achieved with properly oriented fibres. I have always been told that the Titanal contributes considerably more than simple torsional strength.

The isotropic behavior contributes a great deal more to torsional stiffness than most triax fiber fabrics. This is due to the fact that most of these triax fabrics have a lot more fibers running in the longitudinal direction than the +-45. As most manufacturers are trying to keep their product light, they sacrifice torsional rigidity for longitudinal stiffness. Obtaining in plane isotropic fabrics on the small quantities required by a small manufacturer is challenging.

[BlueB]

Ohter benefit might be the resonance dissimillarity of titanal and carbon/glass?

[KingCrimson]

Ohter benefit might be the resonance dissimillarity of titanal and carbon/glass?

This brings about a VERY fun "board game" (teehee) if you have some buddies with nice quivers. Or in your case, some buddies to ride your nice quiver.

We call it Hero, but it's CO ice.. The snow gets slushy, the cats hit it at 4pm, it freezes all night at 20 degrees and 0% humidity. It's super consistent in the morning, but not exactly comfortable to fall on.

Skidding sideways over the groom lines makes some cool sounds. If you listen carefully, you can hear the harmonics when the board is between grooming ridges. Older no-top WCR metals scream and whine, it's weird. I assume the increased frequency and conversely decreased magnitude is why those boards ride so well.

[KingCrimson]

Ohter benefit might be the resonance dissimillarity of titanal and carbon/glass?

This brings about a VERY fun "board game" (teehee) if you have some buddies with nice quivers. Or in your case, some buddies to ride your nice quiver.

We call it Hero, but it's CO ice.. The snow gets slushy, the cats hit it at 4pm, it freezes all night at 20 degrees and 0% humidity. It's super consistent in the morning, but not exactly comfortable to fall on.

Skidding sideways over the groom lines makes some cool sounds. If you listen carefully, you can hear the harmonics when the board is between grooming ridges. Older no-top WCR metals scream and whine, it's weird. I assume the increased frequency and conversely decreased magnitude is why those boards ride so well.

[kieran]

Skidding sideways over the groom lines makes some cool sounds.

i recall a similar effect in the old atomic and K2 skis during the 90's. if you managed to straddle groom peaks while slightly on edge, you would get this eerie resonating noise. don't seem to notice it these days with the new ski shapes.