全 文 ：2 0 1 1 年 11 月 农 业 机 械 学 报 第 42 卷 增刊
Matching of Cutting and Feeding Speed for Reaping
Arundo donax L． Based on ANSYS /LS-DYNA!
Liao Yitao Liao Qingxi Shu Caixia Tian Boping Huang Haidong
(College of Engineering，Huazhong Agricultural University，Wuhan 430070，China)
Abstract
The crops with thick-tall stem are difficult to be harvested by machine due to hardness and stiffness of the stem． In the
present study，a dynamic simulation model of Arundo donax L． penetration was established by finite element numerical
simulation technology，of which based on a general rotary-chain cutter for thick-tall stem． The results showed that the
optimized matching parameters of cutting process for cutting and feeding speed were 2. 80 m /s and 1. 00 m /s，respectively．
The optimal correction factor of cutting process for Arundo donax L． was 1. 22． The study provided a methodological basis
for the analysis of cutting process for thick-tall stems．
Key words Arundo donax L．，ANSYS /LS-DYNA，High-speed photography，Cutting process，Thick-tall stem crop
CLC number:S225. 5
Document code:A
Article ID:1000-1298(2011)S0-0030-05
Received date:2011-08-15 Accepted date:2011-08-29
* Supported by Fund of Independent Innovation of Huazhong Agricultural University (2011PY021)
Biography:Liao Yitao，lecturer，majored in agriculture mechanization engineering，E-mail:liaoetao@ mail． hzau． edu． cn
Corresponding author:Liao Qingxi，professor，majored in agriculture mechanization engineering，E-mail:liaoqx@ mail． hzau． edu． cn
Introduction
For thick-tall stem crops，it is very hard to cut by
manual or machine due to hardness and stiffness and
the specific biological characteristics． It is the greatest
obstacle for the large-scale cultivation of these crops．
The existing researches mainly focused on harvester for
corn and sugar cane， and those researches have
achieved good results in this field［1 ～ 4］． But few study
was focus on other thick-tall stem crops，like giant reed
(Arundo donax L．) ，which is the good raw material of
papermaking．
Aiming on the harvest issue of Arundo donax L．，
a general rotary-chain cutter was developed［5］． The
initial field test demonstrated that this cutter was able
to apply in a harvest machine of Arundo donax L．，but
further research of its structures and parameters was
necessary for optimizing the efficiency of harvest［6］．
Especially for the matching of cutting speed of the
cutter and the feeding speed of the machine，it was one
of the key factors affecting energy consumption，cutting
quality and efficiency of the harvester． But the actual
situation and working condition of the cutter and
cutting process was complex， and was difficult in
analyzing． In the present study，numerical simulation
and high-speed photography will be used to explore the
matching of cutting and the feeding speed．
1 Finite Element Model of Cutting Process
The researches on some physical and mechanical
parameters of the bottom stem of Arundo donax L． in
harvest period have been carried out previously［7］． It
indicated that Arundo donax L． might be approximated
as transversely anisotropic material，and had complex
structure as a biological material，but the characters
like viscoelastic and anisotropy had not been well
reflected［8］． In order to comply with the regulation of
the software ANSYS /LS-DYNA，making reference to
relevant literature of agricultural materials［9］， the
mechanical properties of wood［10］ and bamboo［11 ～ 12］，
the Arundo donax L． material was simplified as
motivated plastic materials，which material parameters
were input as:elastic modulus 0. 8 GPa，Poissons
ratio 0. 34， density 0. 55 × 10 －3 g /mm3， yield
strength 0. 01 GPa and shear modulus 0. 32 GPa．
According to statistic result of the growth of Arundo
donax L． in the field，the geometric parameters were
defined，including 24 mm as external diameter D，
17 mm as the internal diameter d，2. 5 mm as thickness
of node s，and 300 mm as length of single-section with
both side nodes． In addition， the enhancing
phenomenon of node fibroblast was neglected．
The serrated prototype was the blade of the cutter，
which is of double-metal composite［13］， material
parameters being approximated as steel，and simplified
as linear elastic material in numerical simulation model
with 21. 0 GPa as elastic modulus，0. 284 as Poissons
ratio and 7. 5 g /mm3 as density ［14］， while the
geometric parameters were input，including 50 mm as
saw width b，3. 5 mm as tooth depth h，8 mm as
distance between teeth t，33° as front cutting angle α，
47° as tooth vertex angle β，and 10° as back cutting
angle γ ［13］．
The cutting model of Arundo donax L． (Fig． 1)
was established by using solid164 element，defining
the contact as CONTACT_ERODING_SURFACE_TO_
SURFACE between blade and Arundo donax L．，where
blade was contact component and Arundo donax L． was
target component． The part near the contact region was
meshed by improved grid density in order to enhance
the solution accuracy without more increase of
computation quantity． Both sides of Arundo donax L．
were imposed constraints．
Fig． 1 Finite element model of Arundo donax L．
2 Verification Experiment
2. 1 Loading and Displacement Experiment
The RGT computer-servo material testing system
(Shenzhen Rreger Instrument Co．，Ltd．，Guangdong)
was used in the test，of which the type was RGT-10，
the specification was 10 kN，the precision of rank was
± 0. 5% ． As the experiment system shown in Fig． 2，
the blade was fixed by fixture， Arundo donax L．
sample could be vertically cut with various velocities．
This experiment system offered the load-displacement
result of destroy test as curve which was utilized to
confirm the numerical simulation model．
2. 2 Cutting Process Experiment
The experiment system was consisted of two
subsystems:the test-bed based on the general rotary-
Fig． 2 Load-displacement test of Arundo donax L．
penetration
chain cutter and a high speed video subsystem． The
self-designed test-bed was shown in Fig． 3． The high
speed video subsystem included a Mikrotro’s speed
camera MC1311，a Nikko’s lens ZOOM-Nikkor and
an image capture board INSPECTA-5 Frame Grabber
which was installed in the high-powered computer．
This system was used to analyze the cutting process
with the images of the ultra-short process of the blade
cutting down Arundo donax L． at various cutting
condition．
Fig． 3 Test rig of cutting process
1． Cutter platform 2． Cutter 3． Cutting power 4． Feeding platform
5． Feeding chain 6． Feeding power 7． Fixture of Arundo donax L．
3 Results and Discussion
3. 1 Numerical Simulation Analysis
The load-displacement curves (the cutting speed
vx = 3. 00 mm /s，the feeding speed vy = 0 mm /s)were
shown in Fig． 4． The thick curve was came from the
disposal of numerical simulation by software namely
LSPREPOSTD，while the thin curves were came from
loading and displacement experiments． The figure
indicated that the curves of numerical simulation and
real test were consistent，and both maximal loadings of
damage were nearly 450 N． Comparing the damage of
Arundo donax L． in numerical simulation and the
damage of Arundo donax L． in real test (Fig． 5) ，it
could be concluded that the damages were similar．
Both of the load-displacement curves and breach
13增刊 廖宜涛 等:基于 ANSYS /LS-DYNA的芦竹切割-进给速度匹配研究
situation were confirmed the validity and feasibility of
the numerical simulation model．
3. 2 Optimal Cutting and Feeding Speed
Based on the high video image analysis under
various speed， the cutting process observing
experiment revealed that a big value of feeding speed
would make it impossible for cutter to cut down Arundo
donax L．，in detail，the cutting could not be achieved
if the feeding speed vy exceeded 1. 38 m /s while
whatever the cutting speed vx was． Several images
captured at 2 000 frame per second by the high-speed
video subsystem were showed Fig． 6． Fig． 6a presented
the cutting situation when vx = 3. 50 m /s and vy =
1. 50 m /s． The stems were torn apart by the cutter．
The stem was torn apart by the cutter． Fig． 6b
illustrated how the cutter pushed over the stems entirely
when vx = 3. 50 m /s and vy = 2. 00 m /s． On the other
hand，a small value of feeding speed would cause the
cutter working of low efficiency． Considering both the
harvester and working condition，the feeding speed vy
was set at 1. 00 m /s．
It was known that when the blade moved a tooth
depth along feeding way and it also moved two teeth
spaces along the cutting way，each track of blade
movement was neither superposition nor gap in perfect
surrounding． The matching between cutting and
feeding speed would be optimal． In this paper，λ was
defined to describe the ratio of cutting and feeding
speed matching as
Fig． 6 Image of cutting process of Arundo donax L．
captured by high-speed video capture
(a)vx = 3. 50 m /s and vy = 1. 50 m /s
(b)vx = 3. 50 m /s and vy = 2. 00 m /s
λ =
vx
vy
= th
Tests revealed that when the speed of cutting and
feeding was defined according to the perfect ratio λ，
Arundo donax L． could not be cut down in proper
condition，while theory analyses demonstrated that the
value of the perfect ratio should be insufficiency
without considering Arundo donax L． stem rebounding
and contacting with the gingiva during cutting process．
In order to settle this problem， the concept of
correction factor about the matching speed of cutting
and feeding was presented as μ，which value should be
changed along with the species of thick-tall stem crop．
The optimal matching ratio was defined as
λA = μ
vx
vy
= μA
t
h
where，μA—the correction factor about Arundo donax
L．
λA—the ratio of optimal matching
Numerical simulation results with various vx under
the same feeding speed (vy = 1. 00 m /s)indicated that
if μA ＜ 1. 20 m /s，namely vx ＜ 2. 74 m /s，Arundo
donax L． could not be cut down． As Fig． 7 showed，
when vx = 2. 70 m /s，vy = 1. 00 m /s，Arundo donax L．
had distortion without damage， and the numerical
solution alarmed． Fig． 8 showed cutting status of
successful solution when vx = 3. 80 m/s，vy = 1. 00 m/s，
of which Arundo donax L． was cut off by blade．
Tab． 1 showed the maximal power and the average
energy of single Arundo donax L． being cut down by
blade under various cutting velocities． It showed that
single Arundo donax L． cutting energy consumption
would increase along cutting speed increase．
23 农 业 机 械 学 报 2 0 1 1 年
Fig． 7 Arundo donax L． breach situation with
sawing speed at 2. 70 m /s
Considering the vibration of the actual work and other
practical condition，when the feeding speed of was
Fig． 8 Arundo donax L． breach situation with
saw speed at 3. 00 m /s
1. 00 m /s，the optimal cutting speed was 2. 80 m /s，
and the correction factor of matching ratio was 1. 22.
Tab． 1 Sawing performance parameters
Parameters
vx /m·s － 1
2. 80 3. 00 3. 20 3. 40 3. 60 3. 80 4. 00
Max power /W 1 436. 7 1 298. 1 1 956. 4 2 335. 1 2 179. 2 1 719. 5 2 514. 1
Average energy /J 18. 4 22. 6 35. 2 29. 0 40. 0 33. 2 47. 1
4 Conclusions
(1)The numerical simulation model of the
cutting process was established based on ANSYS /LS-
DYNA and was confirmed through comparing the load-
displacement curves and damage status of numerical
simulation and experimentation．
(2)The cutting process experiment indicated that
the cutting should not be achieved if vy ＞ 1. 38 m /s
while whatever vx was，the optimal feeding speed was
1. 00 m /s．
(3)The concept of correction factor of the rate of
cutting and feeding speed was presented;the numerical
simulation indicated that the value must be more than
1. 20 m /s when the general rotary-chain cutter being
used to reap Arundo donax L．
(4)The energy consumptionfor cutting single
Arundo donax L． was increased along with the cutting
speed increase． The optimal matching parameters of
cutting process for cutting and feeding speed were
2. 80 m /s and 1. 00 m /s， respectively． And the
optimal correction factor of cutting process for Arundo
donax L． was 1. 22．
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基于 ANSYS/LS-DYNA的芦竹切割-进给速度匹配研究
廖宜涛 廖庆喜 舒彩霞 田波平 黄海东
(华中农业大学工学院，武汉 430070)
【摘要】 高粗茎秆作物因茎杆硬度和刚度大，机械化收割难度大。以芦竹为对象，以高粗茎秆作物通用型回
转链式切割器为基础，应用 ANSYS /LS-DYNA建立了锯片-芦竹切割破坏动态模拟有限元模型，动态模拟了芦竹切
割破坏过程，试验验证了获取锯齿切割破坏芦竹过程的载荷-位移历程曲线的可行性及芦竹破坏的模拟计算模型
的有效性。提出了回转链式切割器切割-进给速度匹配修正系数概念，确定了切割芦竹时进给速度和切割速度分
别取 1. 00 m /s和 2. 80 m /s为最佳速度匹配，其切割器工作速度匹配修正系数为 1. 22。研究结果为芦竹收割机的
传统系统参数优化设计提供了理论依据。
关键词:芦竹 ANSYS /LS-DYNA 切割过程 高粗茎秆
中图分类号:S225. 5 文献标识码:A 文章编号:1000-1298(2011)
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S0-0030-05
(上接第 29 页)
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43 农 业 机 械 学 报 2 0 1 1 年