| 1. |
- Gren, Per, et al.
(författare)
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Laser vibrometry measurements of vibration and sound fields of a bowed violin
- 2006
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Ingår i: Measurement science and technology. - : IOP Publishing. - 0957-0233 .- 1361-6501. ; 17:4, s. 635-644
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Tidskriftsartikel (refereegranskat)abstract
- Laser vibrometry measurements on a bowed violin are performed. A rotating disc apparatus, acting as a violin bow, is developed. It produces a continuous, long, repeatable, multi-frequency sound from the instrument that imitates the real bow-string interaction for a 'very long bow'. What mainly differs is that the back and forward motion of the real bow is replaced by the rotating motion with constant velocity of the disc and constant bowing force (bowing pressure). This procedure is repeatable. It is long lasting and allows laser vibrometry techniques to be used, which measure forced vibrations by bowing at all excited frequencies simultaneously. A chain of interacting parts of the played violin is studied: the string, the bridge and the plates as well as the emitted sound field. A description of the mechanics and the sound production of the bowed violin is given, i.e. the production chain from the bowed string to the produced tone.
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| 2. |
- Olsson, Erik, et al.
(författare)
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Sound field determination and projection effects using laser vibrometry
- 2006
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Ingår i: Measurement science and technology. - : IOP Publishing. - 0957-0233 .- 1361-6501. ; 17:10, s. 2843-2851
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Tidskriftsartikel (refereegranskat)abstract
- Sound measurements using laser vibrometry have the advantage that field measurement can be obtained through scanning. It is a non-contact method that provides both qualitative and quantitative information. However, it must be noted that the measurement is an integral along the path of the probing beam. Some effects of this projection are investigated both through measurements and calculations. The sound field calculations are made from measured surface vibrations and they are in good agreement with the measured sound field. The calculations show that the projections very much depend on parameters such as integral depth, or probing depth, and the orientation of the sources. In addition to this, the calculated, or measured, amplitude experiences an enhancement which depends on the wavelength and the distance from the sound source. This enhancement can even result in increasing amplitude with distance. Even though this makes the quantitative data obtained not trustworthy, it is a benefit for the qualitative results which become clearer.
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| 3. |
- Pappadà, Silvio, et al.
(författare)
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Mechanical and vibration characteristics of laminated composite plates embedding shape memory alloy superelastic wires
- 2009
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Ingår i: Journal of materials engineering and performance (Print). - : Springer Science and Business Media LLC. - 1059-9495 .- 1544-1024. ; 18:5-6, s. 531-537
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Tidskriftsartikel (refereegranskat)abstract
- Currently, there is a great interest in the study of shape memory alloy (SMA) composites, since SMA wires with a small diameter have become commercially available. Many potential uses have been found for SMA composites in shape control, vibration control, and for the realization of structures with improved damage tolerance. In this work, two types of SMA-hybridized composites are presented for investigating the mechanical and vibration characteristics. The first one contains unidirectional superelastic SMA wires, while the other has been realized with embedded knitted SMA layers. The samples from these laminates have been tested according to "Charpy method" (ASTM D256) and static flexural test method (ASTM D790) to evaluate the influence of the integration of thin superelastic SMA wires on the impact behavior and the mechanical properties of the hybrid composites. Moreover, since the SMA wires are expected to give damping capacity, by measuring the vibration mode of a clamped cantilever using laser vibrometry, the influence of both SMA arrangements on the vibration characteristics has been investigated. Finally, further tests have been carried out on composite panels realized by embedding unidirectional steel wires to distinguish the influence of the martensitic transformation from the pure introduction of a metallic wire into the polymeric matrix.
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| 4. |
- Rantatalo, Matti, et al.
(författare)
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Laser doppler vibrometry measurements of a rotating milling machine spindle
- 2004
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Ingår i: Eighth International Conference on Vibrations in Rotating Machinery. - Bury St Edmunds : Professional Engineering Publishing Ltd. - 1860584470 ; , s. 231-240
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Konferensbidrag (refereegranskat)abstract
- Finding an optimum process window to avoid vibrations during machining is of great importance; especially when manufacturing parts with high accuracy and/or high productivity demands. In order to make more accurate predictions of the dynamic modal properties of a machining system in use, a non-contact method of measuring vibrations in the rotating spindle is required. Laser Doppler Vibrometry (LDV) is a non-contact method, which is commonly used for vibration measurements. The work presented consists of an investigation into the use of LDV to measure vibrations of a rotating tool in a milling machine, and the effects of speckle noise on measurement quality. The work demonstrates how the axial misalignment and the roundness of a polished shaft can be evaluated from LDV measurements. © IMechE 2004.
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| 5. |
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| 6. |
- Sjödahl, Mikael, et al.
(författare)
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Laser metrology in experimental mechanics
- 2005
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Ingår i: 10th NOLAMP Conference. - Luleå : Luleå tekniska universitet. - 9163172283 ; , s. 41-52
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Konferensbidrag (refereegranskat)
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| 7. |
- Svenningsson, Inga, et al.
(författare)
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Exploring the mechanics of adhesion in metal cutting
- 2023
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Ingår i: The International Journal of Advanced Manufacturing Technology. - : Springer. - 0268-3768 .- 1433-3015. ; 127, s. 3337-3356
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Tidskriftsartikel (refereegranskat)abstract
- The deterioration of the cutting edge during machining influences production cost and productivity. The adhesion is one of the main wear mechanisms. This study delves into the adhesive mechanism in the context of turning, milling, and drilling, focusing on three different cutting materials: 34CrNiMo6, 1.437 stainless steel, and ductile iron. Building upon previous research on the adhesive process in turning, a dynamic model was developed to understand the mechanism further. The results showed that adhesion is a general phenomenon occurring in all tested work materials, but with varying intensity levels. Intermittent cuts did not greatly impact the adhesive mechanism, and cutting data, coolant, and chip breaking also showed little effect. However, the presence of graphite in ductile iron temporarily inhibited adhesion. The source of the adhesive sound was found to be the pivoting movement of the chip as it binds and rips off the cutting tool, leading to a frequency shift upon detachment. The adhesive wear was found to be a thermal mechanism, where chemical reactions between the SiO2 in the work material with the cutting tool caused thermal cracks and low-frequency fatigue.
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| 8. |
- Svenningsson, Inge, et al.
(författare)
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On the mechanism of three-body adhesive wear in turning
- 2021
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Ingår i: The International Journal of Advanced Manufacturing Technology. - : Springer. - 0268-3768 .- 1433-3015. ; 113, s. 3457-3472
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Tidskriftsartikel (refereegranskat)abstract
- The paper reveals a hypothesis regarding the adhesive mechanism in metal cutting and its mechanical dynamics. One steel grade, 34CrNiMo 6, 285 HB, and one set of coatings on the cutting tool are reviewed. The adhesive mechanism is a transient vibration, including a feedback system limited by the plastic deformation in the chip. The vibration shows as a cluster of waves with stochastic duration in time. It starts up again after a stochastic lapse of silence. The cycle frequency is around 12.5 kHz and the internal excitation is twice that frequency, as the cutting speed and feed are 200 m/min and 0.2 mm, respectively. The adhesive frequency and amplitude are influenced by the cutting speed and the current wear status. The adhesion is monitored by the sound waves emanating from vibrations in the chip, the part still in the workpiece.
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| 9. |
- Svoboda, Ales, et al.
(författare)
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Integrated approach for prediction of stability limits for machining with large volumes of material removal
- 2008
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Ingår i: International Journal of Production Research. - : Informa UK Limited. - 0020-7543 .- 1366-588X. ; 46:12, s. 3207-3222
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Tidskriftsartikel (refereegranskat)abstract
- High-speed machining of thin-walled structures is widely used in the aeronautical industry. Higher spindle speed and machining feed rate, combined with a greater depth of cut, increases the removal rate and with it, productivity. The combination of higher spindle speed and depth of cut makes instabilities (chatter) a far more significant concern. Chatter causes reduced surface quality and accelerated tool wear. Since chatter is so prevalent, traditional cutting parameters and processes are frequently rendered ineffective and inaccurate. For the machine tool to reach its full utility, the chatter vibrations must be identified and avoided. In order to avoid chatter and implement optimum cutting parameters, the machine tool including all components and the work piece must be dynamically mapped to identify vibration characteristics. The aim of the presented work is to develop a model for the prediction of stability limits as a function of process parameters. The model consists of experimentally measured vibration properties of the spindle-tool, and finite element calculations of the work piece in (three) different stages of the process. Commercial software packages used for integration into the model prove to accomplish demands for functionality and performance. A reference geometry that is typical for an aircraft detail is used for evaluation of the prediction methodology. In order to validate the model, the stability limits predicted by the use of numerical simulation are compared with the results based on the experimental work.
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| 10. |
- Tatar, Kourosh, et al.
(författare)
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Digital holographic interferometry for simultaneous orthogonal radial vibration measurements along rotating shafts
- 2008
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 47:18, s. 3269-3274
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Tidskriftsartikel (refereegranskat)abstract
- A digital holographic interferometry setup used to measure radial vibrations along a rotating shaft is presented. A continuous Nd:YAG laser and a high-speed digital camera are used for recording the holograms. The shaft was polished optically smooth to avoid speckle noise from the rotating surface. The light reflected from the shaft was directed onto a diffuser which in turn was imaged by the holographic system. Simultaneous measurements with a laser vibrometer were performed at one point and comparisons between the signals showed good agreement. It is shown that different vibration components of a rotating shaft can be simultaneously measured with this technique.
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