Experimental study on crack irregularity of hollow shell particle under impact loading

Li, Long; Mao, Biqi; Zeng, Yong; Tang, Yurong; Man, Xiaolan; Fan, Xuejun; Zhang, Yongcheng; Zhai, Hong

doi:10.1016/j.powtec.2023.118704

Cited by 6 publications

(6 citation statements)

References 56 publications

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“…The image processing process of the shell fragments is presented in Figure 3. Note that the threshold value, which is used to distinguish the boundaries of the shell fragments, plays an important role in determining shell fragment PA. Research indicates that, when compared to alternative methods like k-means clustering and the watershed algorithm, the adaptive thresholding technique is extensively utilized in boundary extraction due to its heightened robustness and adaptability [3,21]. Thus, the adaptive threshold was used to determine shell fragments' PAs.…”

Section: Experimental Equipment and Methodsmentioning

confidence: 99%

“…The walnut is mainly composed of shell and kernel, and it is increasingly used in various fields such as food, medicine, chemistry and materials [1,2]. Shell breaking is essential for the primary post-harvest processing of walnuts to obtain high-quality kernels and their by-products [3,4]. Unfortunately, the quality of walnuts can be reduced by shell-breaking processing.…”

Section: Introductionmentioning

confidence: 99%

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Determination of Critical Moisture Content Facing Walnut Shell Breaking and Optimization of Combined Hot Air and Microwave Vacuum Drying Process

Li,

Man,

Zhang

et al. 2023

Applied Sciences

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The conditioning of moisture content is an effective way to improve walnut-crushing performance. In this study, firstly, walnuts with different moisture contents were used to conduct the crushing experiments. The distributions of fragment sizes of shells and kernels with different moisture contents were analyzed by an image processing and sieving method, respectively. The results show that moisture content significantly affects the fragmentation degree of the shell and kernel, as shown by the differences in the fractal dimensions of shell fragments and the average fragment size of kernel fragments. The critical moisture contents of the shells and kernels, corresponding to the specific states of broken shells and whole kernels, were determined. Then, taking the critical moisture content as the target moisture content, the combination of hot air and microwave vacuum drying applied to dry walnuts was presented and the process parameters were optimized. Optimized process parameters include a hot air temperature of 63.23 °C, a moisture content of the transition point of 24.88%, microwave power of 588.24 W and a microwave vacuum thermostatic temperature of 49.01 °C. At this point, the unit time drying rate, unit mass drying energy consumption, mean square error of moisture content and kernel color parameters were 0.215%/min, 3.03 kW·h/kg, 2.93% and 6.42, respectively. It was confirmed that drying the walnuts to a critical moisture content using an optimized process could both maximally improve the crushing performance and significantly reduce the drying time. The findings provide important information for conditioning the crushing state of walnuts and improving crushing performance and have practical value for the improvement of drying systems.

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Section: Experimental Equipment and Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Determination of Critical Moisture Content Facing Walnut Shell Breaking and Optimization of Combined Hot Air and Microwave Vacuum Drying Process

Li,

Man,

Zhang

et al. 2023

Applied Sciences

Self Cite

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“…When the drying of rectangular, spherical and other shapes of materials is mainly controlled by the descending drying stage, Fick's second law can be adopted to analyze the process of moisture diffusion inside the material [29]. Generally, the walnut was viewed as a sphere in the theoretical research due to its relatively high sphericity [30]. Therefore, as per Hassan-Beygi et al, the sphere geometric radius (r g ) was derived by measuring the dimension parameters for two hundred walnuts [15].…”

Section: Effective Moisture Diffusivitymentioning

confidence: 99%

Drying Kinetics and Mass Transfer Characteristics of Walnut under Hot Air Drying

Man,

Li,

Fan

et al. 2024

Agriculture

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This study was conducted to investigate the drying kinetics and internal and external mass transfer characteristics of walnuts for an understanding of the drying mechanism. The drying characteristics, mass transfer characteristics, and color of walnut during hot air drying (HAD) were investigated under different initial moisture content (IMC) (0.35, 0.39, and 0.43 g water/g wet mass) and drying temperatures (50, 60, 70, and 80 °C). The results indicated that the IMC and drying temperature both have significant effects on the drying process of walnut, showing the higher the IMC, the longer the preheating time, the smaller the effective moisture diffusivity (Deff) and mass transfer coefficient (hm), and the longer the drying time, but reverse results for drying temperature. The values of Deff and hm for walnut ranged from 4.94 × 10−10 to 1.44 × 10−9 m2/s and 1.24 × 10−7 to 3.90 × 10−7 m/s, respectively. The values of activation energy for moisture diffusion and mass transfer ranged from 21.56 to 23.35 kJ/mol and 28.92 to 33.43 kJ/mol, respectively. Multivariate linear prediction models were also established for estimating the Deff and hm as a function of the HAD process parameters. The drying temperature has a greater effect on the walnut kernel lightness than the IMC. The Verma et al model could be used to describe the HAD process of the walnut. The findings contribute to the understanding of moisture transfer mechanisms in walnuts and have practical value for the evaluation and improvement of drying systems.

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“…However, existing studies have focused more on the rate, morphology, and number of walnut crack extensions. For example, Li et al [11] quantitatively characterized the irregularity of walnut bifurcation based on fractal theory. The rate of walnut crack expansion and the number of bifurcations were analyzed via numerical simulations carried out by Hang et al [12].…”

Section: Introductionmentioning

confidence: 99%

“…Mecholsky et al [17] proposed a method for determining the threshold energy for crack bifurcation based on fractal theory. The method was successfully applied to determine the energy of walnut crack bifurcations by Li et al [11]. However, it is well known that the process of crushing walnuts inevitably begins with the cracking of the material, followed by the bifurcation of cracks.…”

Section: Introductionmentioning

confidence: 99%

Study on the Relationship between Crack Initiation and Crack Bifurcation in Walnut Shells Based on Energy

Man,

Li,

Zhang

et al. 2023

Agriculture

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Clarifying the dissipated energy required for crack expansion is an effective way to control material crushing. Therefore, based on the material fracture probability model and fractal theory, the energy range required for crack extension was determined, and the morphology of the cracks was quantified. This study investigates the influence of walnut size on crack propagation characteristics; this includes its effects on the crack initiation threshold energy, representing resistance to crack initiation, and the crack bifurcation threshold energy, representing resistance to crack bifurcation. The results show that crack extension has a well-defined threshold energy below which cracks do not initiate or bifurcate. The size of walnuts significantly impacts crack propagation characteristics, showing that both crack initiation threshold energy and crack bifurcation threshold energy decrease with increasing walnut sizes. In addition, there is a positive correlation function between the crack initiation threshold energy and the crack bifurcation threshold energy. The experimental results can offer fresh insights into material fracture prediction and serve as a reference for numerical simulations.

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Experimental study on crack irregularity of hollow shell particle under impact loading

Cited by 6 publications

References 56 publications

Determination of Critical Moisture Content Facing Walnut Shell Breaking and Optimization of Combined Hot Air and Microwave Vacuum Drying Process

Determination of Critical Moisture Content Facing Walnut Shell Breaking and Optimization of Combined Hot Air and Microwave Vacuum Drying Process

Drying Kinetics and Mass Transfer Characteristics of Walnut under Hot Air Drying

Study on the Relationship between Crack Initiation and Crack Bifurcation in Walnut Shells Based on Energy

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