ANALYSYS & OPTIMIZATION OF HYDRAULIC … & OPTIMIZATION OF HYDRAULIC EXCAVATOR ... of finite element...

DOI : 10.23883/IJRTER.2017.3144.XNO0N 267

ANALYSYS & OPTIMIZATION OF HYDRAULIC EXCAVATOR

BUCKET TEETH USING FEM

Shailesh sharma1, Alok Sharma2 1,2 Mechanical Engineering Department, SSTC Bhilai

Abstract— In this paper various configurations of the bucket teeth have been designed in order to

perform static analysis. The analysis has been carried out by using ANSYS14.5 where various

configurations of teeth are designed as per SAE J1179 standard and using boundary condition for the

maximum digging force condition all the design teeth are subject to maximum force. The effect of

maximum digging force has been observed on maximum tooth deformation and Maximum

Equivalent Von-Mises stress. In order to validate the obtained results are compared with the

available literature and the results are within acceptable limit. Moreover, the effect of fillet on the

teeth tip has been observed in terms of maximum total deformation and Von mises stresses. And the

optimum condition of the fillet has been proposed for the all the configuration of the bucket teeth.

Keywords—Bucket excavator, Bucket Teeth, Deformation, Failure teeth

I. INTRODUCTION

A hydraulic excavator (digger) is an outsized vehicle that is build up for demolition and

excavation purposes. A conventional hydraulic excavator consists of various parts but the basic

prime parts are boom, chassis, and bucket, and move using wheels or tracks. They are available in a

wide range in size and function, an instance of which is the comparable but smaller “mini

excavator.” All versions are usually designed for the same intentions. Hydraulic excavators weigh

lying 3,000 and 2 million pounds and their speed varies between 19 HP and 5,000 HP.

Conventionally, Hydraulic excavator bucket is made up of selling steel and normally tooth

present, which is protruding from the cutting edge, is to disrupt hard material and prevents from

wearing-and-tearing of the bucket. The excavator bucket tooth has to stand heavy loads of materials,

for example, wet soil and rock furthermore, it also subjected to abrasion wear because of the abrasive

nature of soil particles when tooth acting to disintegrate material. Generally, for making tooth of

excavator bucket alloy steel is used along with the addition of some other wear resistant materials so

that its life will improve against abrasive wear. Using alloy along with solid steel is basically due to

having both good toughness and abrasive resistance as of having direct contact of metallic

components with the soil constituents. Therefore, better selection of tooth material and tooth design

should be undertaken in order to prevent from bucket tooth failure.

II. LITERATURE REVIEW

Maciejewski et al. 2004 conduct an experiment to investigate soil cutting problem. And

concluded that the tool width equalled the width of the soil bin, the soil cutting problems might be

treated as plane strain processes. Moreover in their next paper they conduct a new experiment to

analyze the bucket equipped with teeth. And the effect of no. of teeth and teeth spacing has been

examined in order to enhance the digging cycle efficiency.

Coetzee et al.2007 presents an 2Dimensional discrete and continuum modelling of excavator

bucket filling. Discrete element method and material-point method are used and compared with

experimental results and conclude that The DEM model does not accurately predict the material flow

during filling, while the polar and non-polar techniques are more accurate.

International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 04; April - 2017 [ISSN: 2455-1457]

@IJRTER-2017, All Rights Reserved 268

Knight 2009 analyzed the shovel dipper teeth and evaluate the Optimal replacement intervals.

a novel technique called ‘grouped failure data with multiple suspensions has been used and conclude

that using this replacement interval a saving of US$ 300,000 per shovel per year can be achieved.

Eugeniusz et al 2010 examined the failure caused by fractured shaft of the bucket wheel. To

analyze the failure discrete model has been developed and using FEM technique analysis has been

carried out. At the fractured region Macroscopic and microscopic image has been taken o analyze the

microscopic characteristics so that such failure of shaft can be be prevented in future.

Jovancic et al. 2011 diagnose Load-Bearing capacity of bucket wheel excavator and found

that the force exerted during excavation operation are required to find these forces for better design

of tool, backhoe parts and for trajectory planning.

Miodrag et al. 2011 examined the failure of bucket wheel caused by residual stresses in

welded joints using FEM approach. The results are compared with the numerical–experimental result

and revealed that the combination of working (dynamic) and residual (static) stress can be over the

limit lines of modified Goodman’s.

Babu and Venu et al.2014 optimized the excavator bucket using finite element method. They

develop and bucket for PC-09 and Zaxis-8-1 using solid works and imported in ANSYS for transient

analysis. They modified some parameters and proposed a optimum design.

Kalpak et al 2015 The Excavator bucket tooth have to bear heavy loads of materials like soil,

rock and subjected to abrasion wear due to the abrasive nature of soil particles. Its tooth got damaged

due to abrasive wear and impact load. This paper deals with review of Excavators bucket tooth

analysis to find out its actual failure.

III. METHODOLOGY

The Bucket teeth has been modeled by using ANSYS 14.5 and it is was discretized into 7208

elements with 39127 nodes For bending and contact stress analysis of the bucket tooth the material

properties has been tabulated in table 5.1 and the dimensions of the teeth are detailed in figure 1 the

develop teeth are as per SAE standards. The meshed teeth in ANSYS 14.5 is shown in figure 2. The

boundary condition applied to the teeth is detailed in Figure 3

Table 5.1 Tooth Material properties [10, 11, 12]

Properties Alloy steel Hardox 500

Density (kg/ m3) 7850

Modulus of elasticity (MPa) 2.1*105

Poisson's ratio 0.29

Yield strength (MPa) 1000

Ultimate tensile strength(MPa) 1250

Impact toughness (J) 30

Brinell hardness 370-500



Figure 1 Tooth Dimension [10, 12]

Standard Teeth



Fanggs Digg Teeth

Long Teeth

Twin Tiger Teeth



Tiger Teeth

Figure 2 Meshed Teeth

Figure 3 Boundary condition for tooth

IV. Result and Discussion

Figure 4 Validation of Maximum total deformation with respect to different tooth configuration



Figure 5 Validation of Maximum Equivalent Von-mises stress with respect to different tooth configuration

Figure 4-5 shows the validation of Maximum total deformation and Maximum Equivalent Von-

Mises stress with respect to different tooth configuration. It has been observed that the obtained

results from Present finite analysis (ANSYS) of various tooth has been compared with the work of

Bilal and Abid [10] and observed that the result shows good agreement and are in the acceptable

range.

Percentage variation has also been tabulated and it has been observed that the maximum deviation in

maximum total deformation has been seen for Long Teeth i.e. ±14% .While minimum for Tiger teeth

i.e. ±0.41%. Similarly for Maximum Equivalent Von-Mises stress maximum total deformation has

been seen for Fanggs Digg Teeth i.e. ±9.68% .While minimum for Abbrasion teeth i.e. ±0.42%.

The variations in results are mainly due to different mesh sizing and taken assumptions during

analysis.

Figure 6.and 7 illustrates the effect of Fillet radius on the Maximum total deformation and Maximum

Equivalent Von-Mises stress of the Tiger Teeth. It has been observed that the the Maximum total

deformation and Maximum Equivalent Von-Mises stress drastically decreases as the fillet radius

increases. This means that introducing fillet reduce the stress level at the tip of the tooth. It has been

analyzed that fillet radius above 1mm to 4mm the teeth are under safe zone and can withstand wide

range of force.

From the above, it can also be concluded that increasing fillet radius from 2mm to 4mm i.e. (100%),

the stress level can be decreased by 43.6025% respectively. Similarly, the rate of deformation can

also be reduced by 38.179%.



Figure 6 Effect of Fillet radius on the Maximum total deformation and Maximum Equivalent Von-mises

stress of the Tiger Teeth

Figure 6.18 Effect of different fillet radius on the Maximum Equivalent Von-Mises stress of the Tiger

Teeth



Figure 7 Effect of different fillet radius on the Maximum Equivalent Von-Mises stress of the Tiger Teeth

V. CONCLUSIONS

On the basis of finite element analysis of exactor bucket teeth following conclusions has been drawn

which are as follows:

The obtained result has been compared with the Bilal and Abid [18] and shows good agreement

and varies in the range of ±0.2-±14.

The effect of introducing fillet at the tip of the teeth has been observed for all configurations of

the teeth and it has observed that majorly in most of the cases increasing fillet radius the

Maximum total deformation and Maximum Equivalent Von-mises stress decreases significantly.

It can be concluded that the fillet radius 0 to 1mm the teeth’s are un-safe and has maximum

possibility of failure. While, for fillet radius 2 to 4mm the teeth’s are under safe limit. This is

due to their Von-mises stress lying below their maximum yield strength. i.e. 1000/2 =500MPa,

where 2 is factor of safety.

It has been observed that the twin tiger tooth is not suitable for excavation of rigid surface. As it

can be used for excavation of densely compacted soil/material normally in such cases, teeth are

not subjected to such high force.

It has been found that the optimum fillet radius should be taken between 2-3mm

REFERENCES [1] J. Maciejewski , A. Jarzebowski , W. Tra mpczynski, Study on the efficiency of the digging process using

the model of excavator bucket, Journal of Terramechanics 40 (2004) 221–233

[2] C.J. Coetzee , A.H. Basson , P.A. Vermeer, Discrete and continuum modelling of excavator bucket filling,

Journal of Terramechanics 44 (2007) 177–186

[3] C.J. Coetzee *, D.N.J. Els, The numerical modelling of excavator bucket filling using DEM, Journal of

Terramechanics 46 (2009) 217–227

[4] P.F. Knights, Optimal replacement intervals for shovel dipper teeth, International Journal of Mining,

Reclamation and Environment, Vol. 23, No. 3, September 2009, 157–167

[5] Eugeniusz Rusin´ ski, Piotr Harnatkiewicz, Marcin Kowalczyk, Przemysław Moczko, Examination of the

causes of a bucket wheel fracture in a bucket wheel excavator, Engineering Failure Analysis 17 (2010)

1300–1312



[6] Jovancic, P.D., Ignjatovic, D., Tanasijevic, M., and Maneski, T., Load-Bearing Steel Structure

Diagnosticson Bucket Wheel Excavator, for the Purpose of Failure Prevention, Engineering Failure

Analysis, 2011, vol. 18, pp. 1203–1211.

[7] Miodrag Arsic´ , Srd-an Bošnjak , Nenad Zrnic´, Aleksandar Sedmak , Nebojša Gnjatovi, Bucket wheel

failure caused by residual stresses in welded joints, Engineering Failure Analysis 18 (2011) 700–712

[8] S.Sekhar Babu, Y.Venu, Design optimization of excavator bucket using Finite Element Method,

International Journal of Research and Innovation (IJRI),Volume: I, Issue : IV, December 22, 2014

[9] Kalpak. S. Dagwar, R.G. Telrandhe, Excavator Bucket Tooth Failure Analysis, International Journal of

Research in Mechanical Engineering & Technology, IJRMET Vol. 5, Issue 2, May - Oct 2015 ISSN :

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[10] Bilal Pirmahamad Shaikh and Abid M. Mulla, Analysis of Bucket Teeth of Backhoe Excavator Loader

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[11] Hydraulic Excavator and Backhoe Digging Forces (Cancelled Mar 2008, Superseded by ISO 6015)

http://standards.sae.org/j1179_200803/

[12] http://www.ssab.com/, http://www.ssab.com/products/brands/hardox

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