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Quantitative Ultrasonics

The ERL Quantitative Ultrasonics Team performs research on complex materials, both manmade and natural. Our interests span everything quantitative that can be done with ultrasonics: evaluation of mechanical properties (stiffness tensor components, shear properties), viscotic properties (loss modulus, attenuation) and changes in them. Most research is done non-destructively, thus allowing the same samples to be probed with other measurement methods.We also combine quantitative ultrasonics with other measurement techniques, e.g. X-ray scattering and mechanical testing.

For further information about the team, please contact the team leader Dr. Ari Salmi, ari.salmi (at) helsinki.fi.

Current EQUATE projects:

Localizing defects in adhesion between a metal hemisphere and a polymer shell

We aim to study whether one can experimentally detect defects in adhesion between a metal hemisphere and a polymer shell. To this end, we built a custom made contact and a non-contact setup to launch ultrasonic waves that propagate along the hemisphere. The presence of extra echoes and changes in the Fourier transform as a function of angle allowed us to quantitatively determine the location of localized non-adhered areas.

 

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Samples. (left) Hemispherical cavity milled into UHMWPE base, a 17.5 mm hexagonal hole in the base is visible. (right) Steel shell dislodged out after gluing, featuring glue everywhere except at the location of the hexagon. The coordinate system used to localize the defect is shown.

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Detecting a localized defect in adhesion. FFT of received signals as a function of θ. (top left) reference sample, (top right) 17.5 mm diameter defect, (bottom left) 10 mm diameter defect and (bottom right) 5 mm diameter defect.

 

 

 

 

 

 

 

 

 

 

 

 

Participating team members: Dr. Ari Salmi, Ms. Olga Heino, Dr. Adam Hacking (affiliated team member, MGH)

Recent publications:

A. Salmi, P. Karppinen, S. A. Hacking, E. Haeggström, Non-contact quantification of adhesion between a metal hemispherical shell and a polymer base by guided acoustic waves, Proceedings of the 2012 IEEE UFFC, DOI: 10.1109/ULTSYM.2012.0362

A. Salmi, O. Heino, H. J. Nieminen, T. Salmi, P. Karppinen, T. Patola, S. A. Hacking and E. Hæggström, Detecting defects in adhesion between a metal hemisphere and a polymer base, Proceedings of the 2013 IEEE UFFC, DOI:

For more information, contact ari.salmi (at) helsinki.fi

In situ quantitative determination of the effects of heavy ion irradiation on SWCNT bucky paper

We aim to quantitatively verify the hypothesis stating that SWCNT bucky paper mechanical properties are improved by heavy ion irradiation. We built a custom-made ultrasonic needle-based setup that was inside the accelerator tube determine the in-plane stiffness values of the samples during the irradiation process.

Implementation of the setup in the accelerator beam tube

 

Participating team members: Dr. Ari Salmi, Ph. Lic. Ilkka Lassila (affiliated team member), M. Sc. Antti Meriläinen (affiliated team member), Dr. Ossi Lehtinen (affiliated team member, Accelerator Laboratory, UH)

Recent publications:

A. Salmi, E. Haeggström, K. Arstila, K. Nordlund and J. Keinonen, Increasing the Stiffness of SWCNT Bucky Paper By Heavy Ion Irradiation, AIP Conf. Proc. 894, pp. 1183-1188

A. Salmi , O. Lehtinen , I. Lassila , A. Kaskela , U. Dettlaff-Weglikowska , A. Krasheninnikov , E. Hæggström , K. Nordlund and J. Keinonen, Engineering SWCNT bucky paper by heavy ion irradiation: An in situ –study, Proceedings of the 2007 ICU, DOI: 10.3728/ICUltrasonics.2007.Vienna.1624_salmi

For more information, contact either ilkka.lassila (at) helsinki.fi or ari.salmi (at) helsinki.fi

Determination of the modulus of the unit cell of materials by a combination of X-rays and ultrasound

We combined standing wave ultrasonics and X-ray diffraction to quantitatively determine the mechanical properties of the unit cell of materials. Part of the research was performed at the ESRF Grenoble facility.

 

Participating team members: Dr. Ari Salmi, B. Sc. Antti Meriläinen (affiliated team member), Dr. Kari Pirkkalainen (affiliated team member, X-ray laboratory), Dr. Mika Torkkeli (affiliated team member, X-ray laboratory)

Recent publications:

A. Salmi, A. Meriläinen, M. Peura, E. Hæggström and R. Serimaa, Microelasticity in Wood Using X-ray Diffraction and Ultrasound, ICU 2007 Conference, Vienna (Talk)

A. Salmi, A. Meriläinen, M. Torkkeli, E. Hæggström and R. Serimaa, Combining X-rays and Ultrasound to Determine Micro-elasticity in Wood, Proceedings of the UFFC 2007, pp. 54-57

A. Salmi, Master’s thesis, 2008

Ongoing research:

Determining Unit Cell Elasticity by Combining X-ray Diffraction and Ultrasound

Past EQUATE projects:

Non-destructive stiffness depth profiling

The aim of this project is to non-destructively quantify the stiffness of solid samples as a function of depth from the surface.

A signal received from a HDPE sample.

For more information, contact ari.salmi (at) helsinki.fi or tuomas.tonteri (at) helsinki.fi

Quantitative evaluation of archaeological wood

(Funded by the Finnish Cultural Foundation)

We determined quantitatively the mechanical properties of waterlogged wood of various age, most prominent shipwreck being the famous Finnish shipwreck Vrouw Maria. Recently, we have been focusing on the monitoring of effects of PEG treatment in conservation of the shipwreck found in Egelskär.

Setup for the evaluation of archaeological samples.

 

Team members participating: Dr. Ari Salmi, Mr. Pasi Karppinen, Dr. Kari Steffen (affiliated team member, Department of Microbiology)

Recent publications:

A. Salmi et al., Ultrasonic quantitative strength assessment of artificially aged and archaeological wood samples, Acoustics ’08, Paris, 2008 (talk)

A. Salmi et al., Non-destructive Evaluation of the 18th century ship wreck Vrouw Maria, Proceedings of the IEEE UFFC 2009, DOI 10.1109/ULTSYM.2009.0359

External links:

Finnish National Board of Antiquities, Condition of the wreck

For more information, contact either ari. salmi (at) helsinki.fi or pasi.karppinen (at) helsinki.fi.

Quantitative Ultrasonic Evaluation of Cyclic Fatigue in Wood

(In collaboration with VTT Technical Research Center Finland and the WoodMat Finnish Academy project)

In this project, we aim to quantify the localized changes in mechanical properties induced by unipolar (forced compression, free relaxation) cyclic loading in wood. We have developed a slice-and-measure based technique which allows quantification of changes in the sample stiffness as a function of depth.

 

 

Recent publications:

A. Salmi et al., Quantifying Fatigue Generated in High Strain Rate Cyclic Loading of Norway Spruce, Journal of Applied Physics 106, 2009, 104905

A. Salmi et al., Quantifying Wood Fatigue Generated in Cyclic Loading, Proceedings of the International Mechanical Pulping Conference 2009 (awarded the ERGS Best Poster award 2009)

A. Salmi et al., Layer-like fatigue is induced during mechanical pulping, Cellulose 2011, DOI 10.1007/s10570-011-9548-5

A. Salmi et al., Significance of fatigue for mechanical defibration, Cellulose 19(2), 2012

A. Salmi, What should the grindstone look like to produce pulp with least energy?, Doctoral dissertation, 2012

 

For more information, contact ari.salmi (at) helsinki.fi.

In Vivo determination of the effects of genetic engineering on the elasticity of Arabidopsis Thaliana

We did in vivo measurements on Arabidopsis plants during their growth, determining the effects of AtCAD1 genetic engineering on the change of ultrasonic velocity as a function of plant age.

Development of the 20% trimmed average of the Landsberg variant at 1 cm height as a function of growth time.

Recent publications:

A. Salmi, K. Mustonen, J. Immanen, Y. Helariutta and E. Haeggström, Genetic manipulation engineers the elasticity of arabidopsis thaliana, Proceedings of the Acoustics ’08 conference, Paris

For more information, contact ari.salmi (at) helsinki.fi

Ultrasonic differentiation of curly- and silver birch

We quantitatively determined the sound velocity and attenuation in curly- and silver birch (curly birch being a variation of the standard silver birch with 10x more value), and developed a computerized differentiation method to distinguish between the two.

Amplitude of the 2nd swing of the ultrasonic signal transmitted through either a silver (blue) and a curly (magenta) birch sample.

 

Recent publications:

A. Salmi, T. Hintikka, P. Forsman, T. Karppinen and E. Haeggström, Computerized Ultrasound Differentiation of Curly Birch from Silver Birch, Journal of Applied Physics 101(1), 2007

A. Salmi, T. Hintikka, P. Forsman, T. Karppinen and E. Haeggström, Automated Differentiation of Curly- and Silver Birch by Ultrasound Attenuation, Journal of Applied Physics, 105, 2009

For more information, contact ari.salmi (at) helsinki.fi.