Mechanical collision simulation of potato tubers

This paper presents the results of an investigation on internal stress progression and the explicit dynamics simulation of the bruising behavior of potato tubers under dynamic mechanical collision. Physical measurements, mechanical tests, advanced solid modeling, and engineering simulation techniques were utilized in the study. The tuber samples used in the simulation were reverse engineered and finite element analysis (FEA) was set up to simulate the collision-based bruising behavior of the potato tubers. The total number of identical tuber models used in the simulation was 17. The numerical data of the FEA results revealed useful stress distribution and mechanical behavior visuals. These results are presented in a frame that can be used to describe bruise susceptibility value on potato-like agricultural crops. The modulus of elasticity was calculated from compression test data as 3.12 MPa. Structural stresses of 1.40 and 3.13 MPa on the impacting (hitting) and impacted (hit) tubers (respectively) were obtained. These stress values indicate that bruising is likely to occur on the tubers. This research paper provides a useful how-to-do strategy to further research on complicated bruising investigations of solid-like agricultural products through advanced engineering simulation techniques. Practical applications: This research aims to simulate realistic dynamic deformation of potato tubers during mechanical collision, which is very hard to achieve through physical or analytical expressions. This is attractive because related food processing industries have shown their interest in determining the physical properties and bruising behavior of food/agricultural products using experimental, numerical, and engineering simulation methods so that it can be used in their food processing technology. Very limited data have been found available in the literature about the subject of FEM-based explicit dynamics simulation of solid-like agricultural crops such as the self-collision case of potato tubers (which is very important for indoor or outdoor potato processing). Comparative investigations on determination of modulus of elasticity are very limited as well. Most of the research focused on single calculation theory and linear static loading assumption-based FEM simulation solutions. Here, we report a “how-to-do” case study for dynamic self-collision simulation of potato tubers

Evaluation of the influence of sugar beet root geometrical features on the interacting force in share-beet root-soil system

Badania eksperymentalne wykonano przy użyciu specjalnych stanowisk do pomiaru siły reakcji korzenia podczas wyorywania oraz siły potrzebnej do wyciągnięcia korzenia z gleby. Stwierdzono korelacje pomiędzy siłą wyciągania korzeni a cechami korzenia jak: długość maksymalna buraka oraz masa buraka wraz z przywierającą do powierzchni warstwą gleby. Istotny wpływ miały także zmienne pośrednie: długość korzenia w glebie, współczynnik kształtu oraz wierzchołkowy kąt stożka korzenia. Stwierdzono także zależność pomiędzy poziomą siłą reakcji korzenia a masą buraka po oczyszczeniu z przywierającej warstwy gleby.Special stands were used to carry out experiments of measuring a reaction force of a root while pulling it out of the soil. Investigations proved the correlation between the pulling-out-force and the following features of the root: maximum length, mass together with layer of the soil sticking to the root. The pulling - out - force is also significantly influenced by the root length in the soil, shape coefficient and the apex angle of the root cone. Horizontal reaction force of the root depends on the sugar beet mass after clearing the root of the soil

Method applied to compare stress relaxation curves for various plant materials

W pracy przedstawiono praktyczne użycie metody porównania przebiegów krzywych relaksacji naprężeń kilku warzyw i owoców. Przebiegi relaksacji naprężeń w walcowych próbkach jabłka, marchwi i ziemniaka przy różnych prędkościach deformacji wstępnej były normalizowane, a następnie aproksymowane równaniem [F0-F(t)]/F0 = abt/(1+bt). Powyższe równanie zawiera dwie stałe mające ścisły związek z cechami kształtu krzywej relaksacji.The work presents practical use of the method allowing to compare characteristics of stress relaxation curves for several vegetables and fruit. Stress relaxation characteristics in cylindrical samples of apple, carrot and potato at various initial distortion rates were normalised, and then approximated by the equation [F0-F(t)]/F0 = abt/(1+bt). This equation contains two constants strictly related to relaxation curve shape features

Selected errors of rheological model parameters determination evaluated on the basis of stress relaxation test for potato tubers

Artykuł prezentuje procedury oszacowania niektórych błędów wyznaczania parametrów modelu Maxwella opisującego zachowanie się walcowych próbek w teście relaksacji naprężeń na przykładzie tkanki ziemniaka odmiany Irga. Wyznaczono błędy zarówno toru pomiarowego jak i wynikające z niedokładności wykonania próbek. Uwzględniono także zmienny w funkcji siły reakcji próbki błąd systematyczny przy wyliczaniu współczynników sprężystości i lepkości dynamicznej modelu.This paper presents the estimation procedures of Maxwell’s model parameters describing the behaviour of potato samples during stress relaxation test. Into consideration were taken errors resulting from an inaccuracy of sample preparation, as well as the used measurement device (defined, limited precision). Moreover systematic error depending on sample reaction force, at calculation of elastic and viscosity coefficients was taken into account

Methodical aspects of determining bruise susceptibility of apples

W pracy przedstawiono analizę możliwości wykorzystania technik pomiaru progu obicia i energii obicia jako parametrów charakteryzujących odporność na obicia jabłek. Badania doświadczalne przeprowadzono na urządzeniu działającym na zasadzie wahadła. Stwierdzono wysoką czułość obu technik co pozwoliło między innymi na różnicowanie owoców świeżych i po przechowaniu. Przyjęta wysokość zrzutu 50 mm umożliwiła osiągnięcie stabilizacji powierzchni obicia już przy piątym udarze. Proponowane techniki pozwalają także na określenie wartości maksymalnego naprężenia dynamicznego przenoszonego przez tkanki jabłka bez wywoływania dalszych zniszczeń.The paper contains a feasibility study for techniques of measuring bruise threshold and bruise energy as the parameters characterizing resistance of apples to bruise. The experiments were made with the aid of a pendulum-based apparatus. High sensitivity of both techniques was found, which made it possible to distinguish between fresh and stored fruits. The 50 mm fall height assumed allowed to achieve stabilisation of bruise surface only at the fifth impact. Proposed techniques allow also to determine the maximum dynamic stress, transferred by an apple tissues without further damage

Using of the "CHMI" technique to determine resistance to bruising for Melrose variety apples

W pracy przedstawiono zastosowanie techniki CHMI do wyznaczania odporności na obicia jabłek odmiany Melrose w warunkach zrzutu z różnych wysokości. Do badań wybrano jabłka zdrowe i niezdeformowane, o różnej masie i średnicy, które zostały przebadane jeden dzień po zbiorze. Dobrane wysokości zrzutu gwarantowały pojawienie się obić podczas pięciu powtórzeń dla każdej wysokości zrzutu. Wartość współczynnika odporności na obicia jabłek wzrastała wraz ze wzrostem wysokości zrzutu, a odporność na obicia była najniższa przy spadku z wysokości 20 mm. Względna, ustabilizowana wysokość odbicia była niezależna od wysokości zrzutu i wynosiła około 50%.The paper presents using of the CHMI technique for determining Melrose variety apples resistance to bruising in conditions of drop from different heights. Healthy and undeformed apples were selected for the tests. The apples had various masses and diameters and were examined one day after harvest. Selected drop heights guaranteed occurrence of bruises during five repetitions for each drop height. The value of apple resistance to bruising coefficient was increasing with growing drop height, and resistance to bruising was lowest for drop from 20 mm height. Relative, stabilised rebound height was independent of drop height and was approximately 50%

Extended X-Ray Absorption Fine Structure Studies of Co Doped ZnS and ZnSe Alloys

X-ray absorption experiments were performed at the Kedge of Co and Zn in Zn$\text{}_{1-x}$Co$\text{}_{x}$S and Zn$\text{}_{1-n}$Co$\text{}_{x}$Se compounds with x = 0.25, 0.16, 0.10, 0.05, 0.00 in the sulphides samples and x = 0.07, 0.02, 0.00 in the selenide ones. Analysis of the extended X-ray absorption fine structure oscillations using phase and amplitudes either from McKale code or from standard samples, gave the distance, number of atoms and the Debye-Waller factors for nearest neighbours. We found that the cation-anion distances Zn-S(Se) or Co-S(Se) are systematically shorter in ZnS than in ZnSe matrix, the Zn-anion distance is always larger than the Co-anion one without any significant Co content dependence. This allowed us to estimate the covalent radius of Co in the studied matrices to be 0.025 Å smaller than the Zn covalent radius and stated that covalent radius of Co is independent of the type of surrounding atoms. In addition the Debye-Waller factors indicated a better ordering in ternary compounds than in the binary standard ones in agreement with rocking curve measurements

Measuring positions for the studies of sugar beet reactive force on some types of mechanical loads

W pracy przedstawiono konstrukcję stanowisk do pomiarów sił reakcji korzeni buraków cukrowych na zadawane typy obciążeń mechanicznych. Uwzględniono separację kierunków działania sił zgodnie z przyjętym podziałem procesu wyorywania na funkcje częściowe. Wyznaczono wartości sił oraz ich przebiegi w czasie, z prędkościami oddziaływania narzędzia zawierającymi się w zakresie prędkości uzyskiwanych przez lemiesz wyorywacza wibracyjnego. Do rejestracji wyników badań wykorzystano zestaw pomiarowy i oprogramowanie firmy Hottinger Baldwin Messtechnik.This paper describes the construction of measuring positions used for determining of sugar beet root reactive forces on some types of mechanical loads. The separation of reactive forces directions was considered according to the given division of lifting process into partial functions. The article presents the course of force values in loading conditions which are similar to real conditions. Measuring set and HBM software were used for data collecting and data processing

Impact characteristics of sugar beet root during postharvest storage

The effects of time of sugar beet root storage on the parameters determined by impact testing were studied. The 9 mm diameter and 20 mm high cylindrical samples were cut crosswise and lengthwise along the root axis. The impact velocity was 1 m s-1 and the change in the response force over time was observed at both ends of the sample. The measurements were made directly after harvesting and after 24, 48, 96 and 120 h of storage at room temperature. Failure stress and strain, impact energy, absorbed energy, Young’s modulus and shock wave speed were determined in the sample tissue from the change in the response force at both ends of the sample. A drop of 40% in the average values of the energy required to damage the samples was observed during 120 h of storage. A similar dependence was found for the energy absorbed by the sample as evidenced by the greater susceptibility of the roots to impact loads. The experiment confirms the importance of critical stress criterion for cylindrical samples of sugar beet. The velocities of shock wave propagation obtained from the samples during impact were in the range of 220 – 384 m s-1 and were not correlated with the other experimental parameters