| 1. |
- Andersson, Patrik, 1974
(författare)
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A contact model for predicting adherence force and noise generation in the tyre / road contact
- 2005
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Ingår i: Proceedings of NOVEM (Noise and Vibration: Emerging Methods), Saint-Raphaël, France.
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Konferensbidrag (refereegranskat)abstract
- Adhesion forces influence the automotive tyre / road surface contact for certain tyre / road combinations, leading to enhanced rolling resistance, tyre vibrations, and noise excitation. A model was developed to predict the contact force and noise generation for hastily separation of two macroscopic objects. The model is formulated in the time domain for two elastic bodies in non-linear dynamic contact. The contact area is spatially discretised in contact points and the dynamic response is calculated convolving the contact forces with pre-calculated impulse responses of the interacting objects. The adhesion forces are included allowing negative forces through the contacts, which break at a given condition; at a critical force in its simplest form. Parameters on a micro-scale influencing this condition are discussed. Time records of contact forces and sound pressures as samples of tyre tread are hastily separated from road surfaces samples were acquired. A qualitative comparison between calculated and measured data demonstrates the feasibility of the model.
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| 2. |
- Andersson, Patrik, 1974, et al.
(författare)
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A Method for Experimental Collection of Global Material Data for Tyres
- 2001
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Ingår i: Nordic Vibration Research 2001, Stockholm, Sweden (The Scandianvian Vibration Society, www.svib.se).
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- For the modelling of the dynamic behaviour of tyres material data are required. Depending on the character of the model these will have different quality. Modelling with global structures such as beams or plates, representative data for the global bending stiffness, global mass etc. are needed. These data do not represent the details of the tyre structure but the combined properties of the structure. Therefore it is not possible to cut out samples of the tyre and determine the global material properties by measurements on these samples. Consequently it is necessary to estimate the material parameter by measurements carried out on the complete tyre. Results from such measurements will be related to the model used for the tyre (e.g. ring model, orthotropic plate, etc.). The material data obtained in such way are consequently a function of both the tyre structure and the model, which is used to update the data. A method for experimental collection of global material data for tyres has been developed. This method is based on the experimental characterisation of tyres by driving point and transfer mobilities and the use of the orthotropic plate tyre model for updating the material data.
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| 3. |
- Andersson, Patrik, 1974, et al.
(författare)
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A study of forces and noise generation in a contact including adhesive bonds
- 2004
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Ingår i: Nordic Vibration Research 2004, June 3-4, (The Scandinavian Vibration Society, www.svib.se).
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Konferensbidrag (refereegranskat)abstract
- Paper to be published.Adhesive forces are present in the contact between a road surface and a rolling tyre. Theses forces may add up to substantial adherence forces, causing stick-snap excitation of tread blocks, high frequency noise generation, and increased rolling resistance. An experimental setup was designed to study the process when a tyre tread block sample was pressed onto a road surface sample, and hastily removed. Time variation of contact forces and sound pressure were measured. The same situation was modelled using a time domain model of two elastic bodies in non-linear dynamic contact. The contact area is spatially discretised in contact points and the contact problem is solved using an elastic half-space. The response of the block is calculated by convoluting the forces with pre-calculated impulse responses of the same block, which is modelled as a mass-spring system. The adhesive bounds are included by allowing negative contact forces; the contact at a point breaks when the calculated contact force reaches a specified negative value. Typical results from the experimental setup and the model are presented. It is concluded that the experimental setup is suitable for investigating the detachment process of the tread block and that the model is able to qualitatively capture the contact force and noise generation.
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| 4. |
- Andersson, Patrik, 1974
(författare)
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Boundary element formulation using modified Green's functions for media with random distribution of scattering objects
- 2009
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Ingår i: Proceedings of NOVEM 2009 Noise and Vibration: Emerging Methods, Oxford, UK.
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Konferensbidrag (refereegranskat)abstract
- The engine bay of an automotive vehicle is a partly open enclosure that is densely filled with numerous objects such as accessory parts, pipes, tubes, and cables. These objects cause scattering of the sound waves inside the engine bay, which leads to an increased absorption of sound power compared to an enclosure without objects. However, it is time-consuming to include all the details of the geometry and acoustical properties of the objects in numerical simulations, predicting the sound power radiated to the exterior. This paper presents how a deterministic boundary element model and a statistical intensity/power model can be combined to give an approximate description of the sound field for cases with randomly distributed scatterers. The boundary element formulation describes the coherent part of the wave field by using modified Green's functions that include the average effect of the scattering objects. The waves scattered at the objects are assumed to result in an incoherent field that is described by an intensity model. The modelling approach is evaluated by calculating the power radiated from a partly open enclosure in a two-dimensional geometry. The results are convincing and it is concluded that the approach is suitable.
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| 5. |
- Andersson, Patrik, 1974, et al.
(författare)
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Boundary Element Method for Intensity Potential Approach : Predicting the Radiated Sound Power from Partially Enclosed Noise Sources
- 2012
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Ingår i: Acta Acoustica united with Acustica. - : S. Hirzel Verlag. - 1610-1928 .- 1861-9959. ; 98:4, s. 588-599
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes the boundary element method for the intensity potential for prediction of high-frequency sound power flow through partial enclosures. The intensity potential approach is based on the local power balance in a lossless medium and the Helmholtz decomposition of the vector field of time-averaged sound intensity. The result is a Poisson equation for a scalar intensity potential. The intensity potential formulation and the boundary element method are both suitable for exterior problems. The governing equations of the intensity potential and the boundary element method for solving this problem are presented. Results from the proposed method are compared with experimental results, for the case of radiated sound power in one-third-octave bands from sources in a partial enclosure. The results show that the method is applicable for estimation of global radiated sound power in one-third-octave bands in the high-frequency range.
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| 6. |
- Andersson, Patrik, 1974
(författare)
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Contact forces and noise generation during hastily separation of tyre tread blocks from road surfaces
- 2005
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Ingår i: Constitutive Models for Rubber IV — Austrell and Kari (eds). - 0415383463 ; , s. 571-577
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Konferensbidrag (refereegranskat)abstract
- Adhesive bonds in the passenger car tyre/road surface contact have a large influence on the contact dynamics for certain tyre/road combinations. The effect is most pronounced for road surfaces with low roughness, so-called smooth surfaces. An experimental setup was designed to study time records of contact forces and sound pressures as tyre tread samples are hastily separated from road surfaces samples. The general character of the separation process on a macroscopic length scale is described, interpreted, and related to theories on smaller scales. A single value (dynamic) adherence force is determined out of the records and it is related to the initial conditions; magnitude of preload, preload duration, and unloading rate. It was found that the exact contact geometry, on larger scales, yields the details in the contact force record and distribution of sound pressure levels in 1/3-octave bands. A model aiming at describing the observed behaviour must consider a wide range of length scales; a dynamic contact model is proposed that considers the exact contact geometry on larger scales via discretisation and uses statistical properties of the surfaces at lower scales to determine contact criteria at contact points.
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| 7. |
- Andersson, Patrik, 1974, et al.
(författare)
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Experimental Study of High Frequency Response of Tyres
- 2003
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Ingår i: EuroNoise2003, May 19-21 2003, Naples, Italy.
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Konferensbidrag (refereegranskat)abstract
- Most traditional tyre models concern the low and middle frequency ranges. It is necessary to include higher frequencies for improved accuracy in tyre/road interaction models. Often only the radial direction is included, although the tangential direction may be important, especially studying stick slip motion in the contact between tyre and road surface. Designing models requires insight into the behaviour of the tyre structure at higher frequencies. To add insight of high frequency behaviour, experimental studies were done on four different tyres with the same internal design but with different tread patterns. The results of this study underline the importance of the local deformation when forces act with small excitation areas on the tread. Adequate consideration of the tread properties in the tyre/road interaction models is thus of importance to obtain the correct local contact force distribution. This is most important for the tangential driving point mobility. Tread patterns are shown mainly to modify the flexural stiffness and mass in comparison to smooth tyres, while block resonances are not expected to be located in the frequency range in which tyre/road noise is important.
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| 8. |
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| 9. |
- Andersson, Patrik, 1974, et al.
(författare)
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Framtidsbilder för samhällsbyggnad
- 2006
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Framtidsbilder för samhällsbyggnad 2020De kommande 15 åren står institutionen för Bygg- och miljöteknik inför stora förändringar. Därför har institutionen initierat projektet Framtidsbilder 2020 där man engagerat en framtidspanel bestående av elva yngre disputerade forskare. Arbetet inleddes med ett breddgruppsmöte där 110 personer representerande institutionens personal och studenter deltog. Vid mötet identifierades ett antal trender och osäkra utvecklingar som påverkar framtiden inom samhällsbyggnadsområdet. Deltagarna bidrog också med idéer till en önskvärd utveckling, vilket har sammanställts och utgör grunden till en gemensam önskvärd framtid/vision för institutionen. Materialet från breddgruppsmötet har bearbetats av Framtidspanelen och resulterat i fyra scenarier som beskriver hur samhällsbyggnadsområdet kan se ut år 2020. Syftet med framtidsbilderna är att de ska vara vägledande för institutionens beslut och förhållningssätt under de kommande åren.Fyra scenarierTurning TorsoSamhället präglas av en ekonomi som är på uppgång, och av ett nytänkande och öppet samhälle. Materiell status och individualism är viktigt. Detta leder till en hög arbetsbelastning samt krav på exklusiva varor av hög kvali-tet. Det finns en stor medvetenhet om miljöpåverkan och klimatförändringar och lösningarna för att klara energiförsörjningen är innovativa.Eco-metropolenDet sveper en grön våg genom dagens samhälle. Under de senaste 15 åren har vi insett att jorden skall vara en bebolig plats även åt dem som kommer efter oss. Vi söker ständigt efter nya, mer förfinade metoder att tillvarata de resurser vi har. Samhället och individen är i balans. Ekonomin är god och vi är miljömedvetna, trygga och integrerade. Nytänkande premieras och icke- materialistiska värderingar står högt i kurs. Vi tänker individuellt, men agerar mer än gärna för kollektivets bästa. Utbildning är gratis TrädgårdsstadenEtt samhälle där vi lärt oss hantera stress, men känner oss otrygga och helst umgås i slutna sociala sammanhang. Vi bor enkelt inne i stan, eller gärna på landsbygden nära storstäderna. Minskade behov av högutbildade i samhället gör att vi har svårt att rekrytera studenter till teknikutbildningar. Det traditionella tankesättet leder till kulturkrockar med företag och personer från andra länder.Gated communitiesFörsämrad ekonomi och ökad egoism har lett fram till ett stressat, otryggt och segregerat samhälle. Accelererande klimatförändringar och ökad miljö-påverkan skrämmer oss, men trots det åtgärdar vi inte problemen, utan koncentrerar oss på konsekvenserna. Arbetslöshet i samhällsbyggnadssek-torn leder till sänkt status för samhällsbyggaren. Vi har därför svårt att rekrytera studenter, och även forskningen har låg status.
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| 10. |
- Andersson, Patrik, 1974, et al.
(författare)
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High Frequency Dynamic Behaviour of Smooth and Patterned Passenger Car Tyres
- 2004
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Ingår i: Acta Acustica united with Acustica. - 1610-1928 .- 1861-9959. ; 90:3, s. 445-456
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Tidskriftsartikel (refereegranskat)abstract
- Most traditional tyre models concern the low and middle frequency ranges. For improved accuracy in tyre/roadinteraction models it is necessary to include higher frequencies. Often only the radial direction is included, althoughthe tangential direction may be important, especially studying stick slip motion in the contact between tyreand road surface. Designing accurate and efifcient models requires insight into the behaviour of the tyre structureat higher frequencies to make the models as complete as necessary without creating tools that are computationallytoo costly. To add insight to this area, experimental studies were done on four different tyres with the sameinternal design but with different tread patterns. Point mobilities were measured and compared with two differenttyre models, a two-layer plate model based on the elastic field equations and an orthotropic plate model. Theresults of this study underline the importance of the local deformation when there are forces that act with smallexcitation areas on the tread. Adequate consideration of the tread properties in the tyre/road interaction modelsis thus of extreme importance to obtain the correct local contact force distribution. This is most important for thetangential driving point mobility. Tread patterns are shown mainly to modify the flexural stiffness in comparisonto smooth tyres, while block resonances are not expected to be located in the frequency range in which tyre/roadnoise is important.
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