This master thesis studies accelerations recorded and stored onboard Scania trucks. From these accelerations, a general load (đč = đ â đ) description is deduced. In the next step, an abstract number, âpseudo-damageâ, representing the loadâs fatigue damage potential is calculated. Method At workshop visits, data stored on-board is âread outâ and stored in a database. Read-outs from Scania test vehicles are used to study how accumulated pseudo-damage evolves with mileage and test cycles. Pseudo-damage intensity (damage per km or test cycle) variation in carefully controlled vehicle operation, i.e. test track vehicle testing, suggests a threshold between random scatter and variation caused by describable load-influencing factors (vehicle specification, road quality, etc). Influence of wheel configuration â two or three axles â on accelerations and pseudo-damage is studied as an example of vehicle specification influence. Result Test track operation produces considerably higher pseudo-damage intensities than operation on public roads. A ânormalâ pseudo-damage distribution is shown on title page. But when the vehicleâs operation is split in two distinctly different modes, the distribution displays two peaks instead. RSD, relative standard deviation of pseudo-damage intensity, is used to quantify scatter and variation. Available data indicates that RSD below 0,3 can be regarded as purely random scatter. RSD values above this threshold suggests that traceable, maybe intentional, variation of loadinfluencing factors is present. A pilot study of axle configurationâs influence on loads (pseudo-damage calculated from acceleration matrices) produces inconclusive results, the available database (number of trucks) is too small. Conclusions and recommendations On-board storage of acceleration data provides a general âfatigue loadâ indication. Resolution is sufficient for meaningful load variation studies. Regular, closer-spaced read-outs would facilitate more detailed studies of test vehiclesâ operation. / Mastersarbetet studerar accelerationer, uppmĂ€tta och lagrade hos Scanias fordon. FrĂ„n dessa accelerationer Ă€r begreppet âpseudo-skadaâ berĂ€knat. Pseudo-skada representerar en lasts utmattnings skada potential. Metod Vid verkstadsbesök sparas den data som finns lagrad ombord pĂ„ lastbilen till en databas. Med utlĂ€sningar frĂ„n testfordonen studeras hur den ackumulerade pseudo-skadan beror pĂ„ miltal och antal körda test cykler. Genom analys utav variationen i pseudo-skada intensitet (skada per km eller test cykel) frĂ„n en vĂ€lkontrollerad fordonsdrift, exempelvis test utförda pĂ„ test banan, fĂ„s ett tröskelvĂ€rde mellan slumpmĂ€ssiga variationer och variationer som beror pĂ„ förklarliga belastningspĂ„verkande faktorer (fordon specifikation, vĂ€g kvalitĂ©, etc.) Som ett exempel pĂ„ influens frĂ„n olika fordon specifikationer, studeras beroendet mellan pseudoskada och hjulkonfiguration. Fordon med antingen tvĂ„ eller tre hjulaxlar Ă€r studerade. Resultat Vid framförande av fordon pĂ„ testbanan genereras högre pseudo-skada intensitet Ă€n nĂ€r fordonet framförs pĂ„ allmĂ€nna vĂ€gar. Figuren pĂ„ titelsidan visar den normala fördelningen utav pseudo-skada. NĂ€r fordonsdriften Ă€r uppdelad i tvĂ„ distinkta körsĂ€tt visar istĂ€llet fördelningen upp tvĂ„ stycken pikar. Relativ standard avvikelse, RSD, av pseudo-skada intensiteten Ă€r berĂ€knad för att kvantifiera slumpmĂ€ssig och betydelsefull variation. TillgĂ€nglig data visar att ett RSD under 0,3 Ă€r att se som slumpmĂ€ssig variation. RSD vĂ€rden över detta tröskelvĂ€rde visar pĂ„ existens utav spĂ„rbara variationer frĂ„n belastningspĂ„verkande faktorer. Resultaten frĂ„n förstudien av beroendet mellan hjulkonfiguration och pseudo-skada Ă€r inte slutgiltiga. Den analyserade datamĂ€ngden Ă€r för liten. Slutsatser och rekommendationer De lagrade accelerationerna ger en generell indikation om âutmattningslastenâ. Upplösningen Ă€r tillrĂ€cklig för att kunna studera de meningsfulla lastvariationerna. Regelbundna utlĂ€sningar, i ett tĂ€tare intervall, skulle frĂ€mja mer detaljerade studier utav fordonsdriften.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:kth-279493 |
| Date | January 2020 |
| Creators | HĂ„rd, Patrik |
| Publisher | KTH, Skolan för industriell teknik och management (ITM) |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | Swedish |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | TRITA-ITM-EX ; 2020:184 |
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