Material and structural modelling of corrugated paperboard packaging for horticultural produce

Starke, Megan Marya (2020-03)

Thesis (MEng)--Stellenbosch University, 2020.

Thesis

ENGLISH ABSTRACT: Corrugated paperboard is the primary packaging material for fresh horticultural produce and plays an integral part in protecting the produce from mechanical damage throughout the cold chain journey. Bruising is the most common form of mechanical damage to fresh produce and is responsible for increased food waste and the associated financial losses. Due to the difficulties in predicting the strength of corrugated paperboard packaging, cartons are often over-designed to withstand the high relative humidity (RH) conditions and large stacking loads during cold storage, and the impact and vibrational loads during transport operations. This thesis further investigates the finite element method (FEM) as a design tool for corrugated paperboard packaging. A simplified material model of the corrugated sandwich structure, in which the corrugated core was reduced to an equivalent homogeneous core, was developed and validated. The material model is based on experimentally obtained material properties for the corrugated board constituents. An experimental study was conducted to investigate the mechanical behaviour of the Mk 4 carton during box compression testing. The Mk 4 carton is one of the primary packaging designs for exporting pome fruit in South Africa. Three different FEM boundary conditions were replicated to investigate their effects on the load-displacement response of the carton. Digital image correlation (DIC) was used to measure the out-of-plane displacement field, and a Tekscan pressure mapping sensor was used to characterize the load distribution between the base of the carton and the platen of the compression tester. A nonlinear finite element (FE) model of the Mk 4 telescopic carton was developed (using the simplified material model) and validated with experimental results. Eight-node solid-shell elements were used in the model, and the touching contact between the inner- and the outer carton was considered in the analyses. The model predicts a collapse load within 3% of the measured value, and there is good agreement between the buckled shape of the model and that of the physical cartons. The model predicts a maximum out-of-plane displacement within 35% of the measured value from the DIC results. The FE model can be used as a design tool if the objective is to design based on compression strength and material requirements. Further work is required to improve the model’s load-deformation response.

AFRIKAANSE OPSOMMING: Geriffelde karton is die primêre verpakkingsmateriaal vir vars groente en vrugte en is belangrik vir die beskerming van die produkte teen meganiese skade gedurende die kouekettingreis. Meganiese skade is die mees algemene oorsaak van kneusing in vars groente en vrugte, en is verantwoordelik vir verhoogde voedsel vermorsing en die geassosieerde finansiële verliese. Kartonne word dikwels oorontwerp om die hoë humiditeit kondisies, groot stapelbelasting tydens koud opberging, en die impak- en vibrasie laste tydens vervoer te weerstaan. Hierdie tesis ondersoek die eindige elementmetode as ’n ontwerpinstrument vir geriffelde kartonverpakking. ’n Vereenvoudigde materiaalmodel van die gelamineerde geriffelde struktuur, waarin die geriffelde kern vereenvoudig word as ’n ekwivalente homogene kern, was ontwikkel en gevalideer. Die materiaal model is gebaseer op eksperimenteel verkreë materiaal-eienskappe vir die golfkartonbestanddele. ’n Eksperimentele studie was uitgevoer om die meganiese gedrag van die Mk 4- karton onder drukbelasting te karakteriseer. Die Mk 4- karton is een van die vernaamste verpakkingsontwerpe vir die uitvoer van kernvrugte in Suid-Afrika. Die effek van drie verskillende grensvoorwaardes op die las-verplasings gedrag van die karton is ondersoek. Digitale beeldkorrelasie is gebruik om die verplasingsveld te meet, en ’n "Tekscan"druksensor is gebruik om die lasverspreiding tussen die basis van die karton en die onderste plaat van die karton-druktoetser te karakteriseer. ’n Nie-lineêre eindige element model van die Mk 4 teleskopiese karton-ontwerp is ontwikkel en gevalideer met eksperimentele resultate. Agtknooppunt soliede-dopelemente is in die model gebruik, en die kontak tussen die binne- en buitenste bokse is in ag geneem in die analise. Die model voorspel ’n ineenstortingslas binne 3% van die gemete waarde, en daar is ’n goeie ooreenkoms tussen die gedeformeerde vormvan die model en dié van die fisiese kartonne. Die model se maksimum buite-vlaks verplasing is binne 35% van die gemete waarde. Die model kan as ’n ontwerpinstrument gebruik word indien die ontwerp gebaseer is op die ineenstortingslas en materiaal vereistes. Verdere navorsing is nodig om die las-verplasings gedrag van die model te verbeter.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/108060
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