DEVELOPMENT OF RUBBER COMPOUND FOR FOR CONVEYOR BELT USING BIO-FILLERS Conveyor belts manufactured in laminated layers from plastics, fibres and natural and synthetic rubbers are used to transport a wide variety of materials. Based on application, conveyor belts are classified c lassified into following groups: •
Highly resistant conveyor belts
•
Oil resistant conveyor belts
•
Food conveyor belts
•
Underground conveyor belts
Based on minimum tensile strength, conveyor belts are classified into three categories: M-24 (Min. tensile strength: 24 MPa) M-17 synthetic N-17 (Min. tensile strength: 17 MPa)
Conveyor belts are composite products composed of matrix (generally rubber) and filler (fibres and particulate fillers). Matrices used in conveyor belts are Natural rubber Styrene-Butadiene Rubber Chloroprene Polyvinylchloride-Nitr Polyvinylchloride-Nitrile ile Rubber Blend Polyvinylchloride Ethylene-Propylene Rubber (EPDM)
Fillers to be used are:
Wood Cellulose Coconut pith
MATRICES NATURAL RUBBER `Vulcanisate properties of natural rubber (A) Strength •
Tensile strength: gum vulcanisates: 17-24 MPa Black filled vulcanisates: 24-32 MPa
•
Good tear strength
•
Good cut-growth resistance
•
Strength of natural rubber vulcanisates decreases with increase in temperature, but better than other elastomers.
(B) Abrasion (B) Abrasion and wear •
Excellent abrasion resistance under mild abrasive conditions.
•
Abrasion resistance can be improved by blending with small amount of polybutadiene.
•
Below 35 C, NR shows better wear than SBR, but above 35 3 5 C, SBR is better.
0
0
(C) Dynamic properties •
NR has high resilience value more than 90% in well cured gum vulcanisates.
•
Fatigue life of NR is superior to that of SBR S BR at large strains, reverse is true for small strains.
Good flex resistance (D)Compression (D)Compression set •
•
Compression set and creep are poorer in NR than th an synthetic polyisoprene.
•
Compression set is reduced by good cure.
Reasons for NR to be used for spring/belt applications Excellent resistance to fatigue cut growth and bearing High resilience Low creep Low heat build-up Reasonably good bonding with metals and fibres
Wide temperature range of use Low cost and
Good processability
Natural Rubber Rubber Conveyo Conveyorr beltings beltings
Top grade conveyor belting can c an be made from NR except those for those used in underground mines. In belt manufacture, good tack and adhesion are very important. Good compound viscosity is also very important in the proper p roper compaction of the belt carcass. In service, NR offers reasonably good resistance to wear and chipping by such abrasive materials as stone, coal and ores. For moderate heat resistance, NR is blended with SBR.
STYRENE-BUTADIENE RUBBER (SBR) The properties of SBR are broadly similar to that of NR. o In comparison with NR and CR, SBR gum vulcanisates have poor mechanical o properties. The raw gum elastomer must have reinforcing fillers. o Higher upper temperature heat ageing resistance than NR. o Cost of raw elastomer is low and comparable with NR. Physical Propertie Propertiess Property Tensile Strength( MPa) Elongation at tear (%) Glass Transition 0 Temperature ( C) Polydispersity
S-SBR 18 565 -65
E-SBR 19 635 -50
2.1
4.5
POLYBUTADIENE RUBBER (BR) High resistance to wear g lass transition Cured BR imparts excellent abrasion resistancedue to its low glass temperature (Tg) BR is usually blended with other elastomers like natural rubber or SBR.
Vulcanisate properties Tensile strength:
2
70 kg/cm
Elongation:
540% 2
Modulus @ 300%:165 kg/cm Hardness (shore A): 59 Tear strength:
2
50.3 kg/cm
ETHYLENE PROPYLENE DIENE MONOMER RUBBER (EPDM) The main property of EPDM is its outstanding heat, ozone and weather resistance. Good resistance to polar substances and steam. Properly pigmented black and non-black compounds are colour stable. Amorphous or low crystalline grades have excellent low temperature flexibility with glass transition points of about minus 60°C. Heat aging resistance up to 130°C can c an be obtained with properly selected sulphur acceleration systems and heat resistance at 160°C can be obtained with peroxide cured compounds. p articularly at high temperatures, if sulphur Compression set resistance is good, particularly donor or peroxide cure systems are used. They can develop high tensile and tear properties, excellent abrasion resistance, as well as improved oil swell resistance and flame retardance. EPM and EPDM are used in highly resistant conveyor belts. Thermal properties of EPDM 0
Max. Service temperature: 150 C 0
Min. Service temperature: -50 C Vulcanisate Properties of EPDM Hardness, Shore A Durometer: Tensile Strength: Elongation: Compression Set: Useful Temperature Range: Tear Resistance: Abrasion Resistance: Resilience:
30 to 95 7 to 21MPa 100 to 600 % 20 to 60% -50° to +160°C Fair to Good Good to Excellent Fair to Good (stable over wide temp. ranges)
Properties of different matrices can be summarised as:
FILLERS Wood Cellulose
The depolymerized celluloses of wood and cotton. It is prepared by methylation and subsequent cleavage of methylates of wood α
celluloses. Cleavage of methylated wood cellulose under conditions of promoting p romoting the complete fission of trimethylated cotton cellulose resulted in dissection of materials into two parts. Another method of production of wood cellulose: c ellulose: acetylation – action of Barnett’s reagents on the wood cellulose under carefully c arefully standardized conditions results in formation of triacetates. Deacetylation of cellulose triacetates produces depolymersied wood cellulose. Methylated depolymerized cellulose is a white powder, which is soluble in chloroform, benzene, pyridine, alcohol and glacial acetic acid and insoluble in acetone.
Coconut Pith
a s coir pith, coir fibre pith, coir dust, or simply coir, is Coco peat, also known as
made from coconut husks, which are by-products b y-products of other industries that use coconuts. It consists of short fibres (<2cm) around 2% ‐ 13% of the total and cork like particles ranging in size from granules to fine dust. Coir dust strongly absorbs liquids and gases. This property is due in part to the th e honeycomb like structure of the mesocarptissue which gives it a high surface area per unit volume. Raw coconuts are washed, heat‐treated, screened and graded before beingprocessed into coco peat products of various granularity and denseness. den seness. Coir pith has a high lignin (31%) and cellulose (27%) content. Its carbon‐nitrogen ratio is around 100:1. Because of the high lignin content left to it, coir pith takes decades to decompose. deco mpose. Coir pith and fibre are widely used along with Rubber and Thermoset and thermoplastics resins to make composites. Most of the works were done to utilize the naturally occurring material in the polymer matrix for the cost reduction and property enhancement purposes.
SELECTION OF MATRIX Depending on the application of o f conveyor belt, following matrices can be used: Highly resistant conveyor belts: NR, EPM and EPDM Oil resistant conveyor belts: NR, CR, NBR and PVC-NBR Food conveyor belt: NR, Polyurethane, PVC-NBR Underground conveyor belt: NBR
PREVIOUS STUDIES ON THIS FIELD Coconut pith was found to have a thermal conductivity equivalent to granular cork and when bound into blocks with rubber latex was found suitable as insulating materials for fish boxes (Pillai and Varier 1952). Coconut pith can be used in fibre resistant building boards (Shrisalkar 1964); thermal insulating concrete (Jain and Goerge 1970); thermal insulation boards (Rao 1971). Viswanathan and L.Gothandapanistudied about the particle board madefrom UF and PF resin using coir pith as the filler. Coir pith with various particle sizeswere
employed to make the composite. Better mechanical properties were obtained forPF resins composite than the UF resin ones. V.G.Geethammastudied on the short coconut fibre natural rubbercomposites and the effect of fibre loading, orientation and chemical modification on theoverall properties of the composites. They treated the fibre with alkali like 5% solutionof sodium hydroxide and sodium carbonate for 48 hrs.and washed to remove the excessalkali content. The fibres are then treated with natural rubber and toluene di isocyanatesolution. The tensile properties, both in transverse and longitudinal directions weremeasured and it was found better values in longitudinal direction. And in the case ofalkali treated + natural rubber and toluene di isocyanate solution treated one, gaveproperty enhancement than that of the alkali treated one. The fibre loading of 40 phrshowed better orientation of fibre in the matrix. But it failed to give a hike in tensilestrength and tear strength values. From another study from the same authors, dynamical mechanical behaviour ofshort coir fibre natural rubber composites was revealed. Short fibre reinforced rubbercomposites can be used in vibration dampers, tires etc. so the study on dynamicmechanical properties are of great interest. The study carried out on various treated anduntreated coir fibres in which, NaOH treatment, Resorcinol Formaldehyde Treatment,Bleaching etc were done. In thetreatments provided, the one with bleaching exhibitedgood dynamic mechanical properties. ChanakanAsasutjaritstudiedon the treated coir fibre green composites. The treatment done to coir fibres were washing in boiling water and then washing incold water. In the first treatment coir fibres were thoroughly washed in excess of watertill the water pH reached 7. By this the water procedure removes a part of extraneouscomponents, such as inorganic compounds, tannins, gums, sugars and colouring matterpresent in coir. The hot‐water procedure removes, in addition, starches. From themorphology obtained it was found that in the surface of treated fibres there was theformation of small pits which increased the total surface area which eventually increasesthe interaction between binder and the filler. From the two treatments boiling and thenwashing in water gave much better properties than the first one. J.Rout studied on the coir polyester amide bio composite. The polyesteramide used was a biodegradable material thus the tag bio composite came. Variouspretreatments were done on the coir fibres which were used for composite preparation,namely alkali treatment, cyanoethylation, bleaching and vinyl grafting. In alkalitreatment the coir fibres were treated with NaOH and then washed in water. Afterdrying, AN and MMA were grafted on the surface of the coir fibre. In cyanoethylationthe coir fibres were obtained by refluxing the alkali treated coir with AN, acetone andpyridine (as catalyst) at 60°C for 2 h, then washing the fibres with acetic acid andacetone, followed by washing with distilled water and finally vacuum drying. The fibre content used was from 30 ‐60 wt%. For the untreated coir composites better propertieswere observed for 50 wt% coir fibre incorporated
composite. Among the treated coir fibre composites, the cyanoethylated one showed better properties than that of theuntreated and other treated fibres. In the case of alkali treated + grafted fibres, the 7%PMMA grafted one showed better mechanical properties. In the case of biodegradabilityof the composite, it showed same characteristics of the biodegradable polyester amideused. S.V.Prasadstudied on the properties of coir fibre polyester composite, inwhich alkali treated coir fibre was used. The coir fibre were soaked in 5% NaOHsolutions for various time spans and their impact on mechanical properties wereinvestigated. It was found that, the time span of 72 to 76 hrs..gave much better propertiesafterwards up to 96 hrs.of time span, the properties p roperties got a decreasing trend. In the case ca se ofchanging alkali solution at every 24 hrs., the mechanical properties found decreasingnature after 48 hrs.of treatment. Scanning electron micrographs revealed that the cellwall thickening and fibre shrinkage was occurring by the alkali treatment. The untreatedcoir fibres were having a smooth surface in which alkali treatment increased surfaceroughness which can be accounted ac counted for the better wettability and increased mechanicalproperties. Wang Wei and Huang Gu carried out studies on coir fibre reinforced rubbercomposite boards. The composites were prepared using compression moulding techniquewith layer by layer construction of coir fibres. Various temperatures viz. 130°C 140°C150°C and 160°C were employed for compression moulding. From these temperatures130°C was found to be the optimum one. As the coir fibres used were having lengthfrom 8 mm to 337 mm, they were not homogenously mixed in the rubber matrix, whichwas evident from the tensile property measurements. From the percentage of fillerincorporation versus Tensile Strength studies, it was found that 60% filler loading wasthe optimum one whereas higher or lower filler content the tensile strength reduces. K.G.Sathynarayana studied on coir fibre‐polyester composites alongwith coir fibre, the studies were carried out in banana fibres, cotton were also used forcomposite preparation. The composites were prepared with an eye on end useapplications like laminates, helmets, roofing, postbox, mirror casing, electrical equipment casing, paperweights etc. the composites were using coir mats incorporatedin polyester resin matrix using hand lay‐up process. These materials gave betterweatherablity properties as that of GRP composites. And a considerable cost reductionand utilization of natural resources were assured. R.V.Silva and co-workers studied on Fracture toughness of natural fibres/castor oil polyurethane composites. Sisal and coconut fibres and woven sisal matwere used for the composite preparation. 10% NaOH solution is used for the alkalitreatment and finally repeated washing in water was equipped. But the properties werelesser for coconut fibre composites than that of sisal fibre ones. But as compared to thepolyurethane matrix, no property enhancement was observed. In the treated fibre section the coconut fibres showed better properties. J. Rout and co-workers studied on the influence of the fibre treatment on theproperties of natural fibre polyester composites. Alkali treatment, cyanoethylation,bleaching and vinyl grafting were the different surface treatments
done on coconut fibre.From the result obtained it was found that the th e surface treatments gave much betteraddition between polymer and filler thus improving mechanical properties in aconsiderable manner. Among the treatments alkali treatment gave better results ascompared to the other three. From a study it was found that in the case of natural fibre, coated with lignin andethylene diamine (EDA) in order to reduce the higher resin consumption and to reducethe moisture absorption. Just half of the resin amount was utilized for the treated fibre ascompared to the untreated one. Even though the tensile and modulus values wereaffected little bit by the treatment and gave less value, considering the economic view,the resin consumption and moisture absorption got reduced.
FORMULATIONS FOR CONVEYOR BELT IN WHICH FORMULATIONS REINFORCINGSILICA REINFORCIN GSILICA IS BEEN USED: U SED: Black conveyor belt cover (NR/BR) Formula: SMR CV60-
80
BR 1208-
20
Vanox ZMTI-
1.1
Carbon black N330 10 Hi-Sil-
40
Vanplast-
2
Sundex790-
2.5
Santoflex 6PPD-
2.5
ZnO-
3
RM Sulphur-
2.5
Santocure MBS-
1.4
Perkacit TMTD-
0.2
This compound was mixed in a 2-wing lab internal mixer 0
ML (1+4) 100 C MU-
15.8
Specific gravity-
1.118
Tensile strength-
23.3MPa
Elongation-
766%
Modulus @200%
2MPa
Modulus @ 300%
4.3MPa
Hardness (Shore A)
59
Tear resistance
85.3N/mm 3
Abrasion Resistance DIN loss 137mm D-Flex Crack Growth,
5 mm
100K cycles,
Black Conveyor Belt Cover (SBR) Formula: Copo SBR1500-
100
Flectol TMQ-
2
Carbon Black N550-
15
HiSil-
50
Stearic Acid-
2
Cumar MH-
10
Calsol510 (NAPH Oil)- 10 Sunproof Reg. Wax-
2
Santoflex 6PPD-
2.5
ZnO -
4
RM Sulphur -
0.5
Santogard PVI-
0.2
Santocure TBBS-
3
Perkacit TMTD -
1
This compound was mixed in a 2-wing lab internal mixer. 0
ML (1+4) 100 C
30+
Specific gravity
1.176
De Mattia Flex, 1000 cycles
8.0mm
Tear Resistance
43.9N/mm
Abrasion Resistance-
147mm
3
CONVEYOR BELT COVER NATURAL RUBBER
80
POLYBUTADIENE RUBBER
20
ZINC OXIDE
5
STEARIC ACID
2
ISAF BLACK
50
AROMATIC OIL
10
ANTIOXIDANT
1.5
SULPHUR
2.5
MBTS
1.0
TMTD
0.2
FORMULATION-2 NR
100
PEPTISER
0.2
ZnO
5
STEARIC ACID
2
ANTIOXIDANT
1
ANTIOZONANT
1
HAF BLACK
45
CI RESIN
2
AROMATIC OIL
6
PARAFFIN WAX
0.5
CBS
0.8
TMT
0.05
PVI
0.1
SULPHUR
2.3
FORMULATION-3
SBR 1500
100
CARBON BLACK N375
40
ZINC OXIDE
5
STEARIC ACID
1
AROMATIC OIL
5
CBS
1
SULPHUR
2.5
ANTIOXIDANT
1.5
ANTIOZANANT
1.5
FORMULATION-4 EPDM
100
YELLOW IRON OXIDE
6
POLYETHYLENE GLYCOL 3350
2
SILICA
50
POLYETHYLENE
3
NAPHTHENIC OIL
20
HYDROCARBON RESIN
2
STEARIC ACID
2
ZINC OXIDE
5
SULPHUR
0.5
TETD
3
ZDMC
3
DTDM
1
MANUFACTURING
1. 2. 3. 4. 5. 6.
DRYING OF FABRIC(FOR COTTON FABRIC) RFL DIPPING(FOR SYNTHETIC FABRIC) FRICTIONING AND TOPPING BELT BUILDING PREHEATING(BY MICROWAVE TECHNIQUE) VULCANISATION & MOULDING a) PRESS CURE b) CONTINUOUS VULCANISATION
DRYING OF FABRIC
Drying of fabrics is essential to avoid blowing of the laminate occurring during the vulcanising operation. The fabric is dried by passage over a multiple stem-heated o drum drier or hot plate at a speed of 15 m per min at a surface temperature of 115 C. A minimum moisture level of 1% for cotton containing fabrics is required. RFL DIPPING
Synthetic filament fabrics, which have been impregnated with adhesive, eg: RFL type, and heat treated, do not usually require pre-drying before skim coating. FRICTIONING AND TOPPING
To ensure good fractioning, a hot fabric is essential. Frictioning on each side is carried out on a three/four roll calendar. The lighter weight fabrics are friction coated, and heavier fabrics are also topped or skim coated to give additional rubber between plies and between the outer plies on covers. It is important that a uniform layer of rubber is applied during the topping operation. BELT BUILDING
Usually full width fabrics to the optimum width of the calendar are used for the calendaring operation, in which both sides sides of fabric are coated simultaneously. simultaneously. The fabrics are then cut accurately to the width required on a cam-cutting machine which as multiple circular cutting knives. The cut widths are adhered together by passing them through a doubling roll arrangement until the correct number of plies plies are obtained. The covers are calendared directly onto the th e belt carcass using a three/four roll calendar; or calendared sheeting is applied on the building table. In the latter case, the completely built belt is then consolidated and passed p assed through pricking rollers to remove any trapped air. PREHEATING
This can sometimes result in substantial reduction of vulcanising time, because materials, such as rubber, are difficult to heat uniformly without degrading their structure. Rubber has high dielectric characteristics and thus can absorb energy of v ery high frequency, generating heat uniformly within the material structure. Micro wave heating is basically similar to dielectric heating but, with the frequency increased from 100 MHz to 2000 MHz. Microwave heating system consists of a power supply to raise the mains voltage to approximately 7Kv, which is then fed to a magnetron oscillator. oscillator. The magnetron oscillator contains within within its vacuum envelope a tuned tuned circuit and delivers the energy via an aerial and waveguide to the applicator.
A typical applicator is a metal chamber , so designed that , for frequency generated, the chamber becomes a resonant cavity. c avity. The laminate is placed inside the cavity: no no direct contact with metal is required as in dielectric heating, and the material can be heated irrespective of the product shape. Even distribution of energy is obtained through cavity design and the provision of a rotary deflector system mounted at each entry point, and perhaps inside the pre-heating chamber. ch amber. VULCANISATION & MOULDING
PRESS CURE
Various types of large flat multi-ram presses are used, of frame or column construction, both single and double daylight. The raw belt is unreeled from a braked brake d ‘let-off’ station to the press, and a section is vulcanised. The presses have cool areas at the ends t prevent over cure between b etween successive sections of the belt. Each press is equipped with stretching gear, usually consisting of flat hydraulically operated clamps, the belts being stretched a given amount prior to closing the press. This stretching is essential to prevent excessive lengthening of belt occurring in service. A moulding frame is made from flat 50-75 50-75 mm wider metal irons placed along each side of the belt. Lateral pressure to form the belt edges is usually applied by hydraulically operated op erated cams which move the metal irons in a fixed amount after the press has been closed on low pressure. The thickness of the metal irons is selected to give 10-12 % compression on the raw belt thickness . The length of cure depends upon the thickness of the belt, and an average cure time 0 would be 17 min at 145 C. On completion of the cure of a section , the next length is indexed into the press, press, the the small small semi-cured semi-cured end section being brought to the exit end of the press and its cure completed on the next operation.
CONTINUOUS VULCANISATION
The belt is passed between between a rotating steel drum and an endless high-tensile-steel high-tensile-steel band, pressure being applied by tensioning the latter hydraulically; heat is applied to both sides of the product, from the internally heated drum dru m and also through the steel band by contact with steam-heated shoes. Typical dimensions of one such machine are as follows: width of steel band, 2m; width of main drum,2.3m; d rum,2.3m; approximate maximum
2
product width,1.9m; drum diameter,1.5m; maximum pressure, 4.8kgf/cm . The maximum product thickness is 32 mm, but the maximum product width varies with the application. The curing speeds are variable between 65m/h and 40m/h, giving cure times of from 3.5 min to 53 min, which adequately covers the range normally required for rubber belting. The belt being fed through the vulcaniser is subjected to an initial initial tension accurately set and maintained, and also to a predetermined stretch.
TESTING 1. 2. 3. 4.
Raw material testing In process testing Functional testing Final product testing
Raw material testing
1. 2. 3. 4. 5. 6.
Plasticity Mooney viscosity Tack Plasticity retention index Die swell and stress relaxation Dynamic stress strain properties
In process testing
1. Tests on rubber compound 2. Tests on rubber vulcanisate
Tests on rubber compound I. II. III.
Rheometeric test Mooney viscosity test Mooney scroch test
Tests on rubber vulcanisate
I. II. III. IV. V. VI. VII. VIII. IX. X. XI.
Hardness Stress strain-tensile strength, elongation at break, modulus Creep/stress relaxation Load deflection Set properties Abrasion Flexing test Heat build up Ageing tests Pressure test Electrical testing
Functional testing
1. 2. 3. 4. 5. 6.
Flammability tests Propane burner test Large scale fire test Drum friction test Surface resistance test Limiting oxygen index test
Final product testing
1. 2. 3. 4. 5. 6. 7. 8.
Flexing test Ageing test Hardness Stress-strain test –tensile strength, elongation at break, modulus Creep /stress relaxation Load deflection Set properties Abrasion
Dynamic mechanical analysis
Dynamic mechanical analysis (abbreviated DMA, also known as dynamic mechanical spectroscopy) is a technique used to study and characterize materials. It is most useful
for studying the viscoelastic behavior of polymers. A sinusoid l stress is applied and the strain in the material is measured, allowing one to determin the complex modulus. The temperature of the s mple or the frequency of the stress a e often varied, leading to variations in the com lex modulus; this approach can be sed to locate the glass transition temperature of the material, as well as to identify tr nsitions corresponding to other molecular motio s. Types of analyzers
There are two main types of DMA analyzers used curre tly: forced resonance analyzers and free resonance analyzers. Free resonance anal zers measure the free oscillations of damping f the sample being tested by suspending and swinging the sample. A restriction to free resonance analyzers is that it is limited to rod or rectangular shaped samples, but samples that can be w ven/braided are also applicable. Forced reso ance analyzers are the more com on type of analyzers available in instrumenta ion today. These types of analyzer force the sample to oscillate at a certain frequency and are reliable for performing a temperature sweep.
Analyzers are made for oth stress (force) and strain (displace ent) control. In strain control, the probe is dis laced and the resulting stress of the ample is measured by implementing a force alance transducer, which utilizes different shafts. The advantages of strain control include a better short time respon e for materials of low viscosity and experimen s of stress relaxation are done with relative ease. In stress control, a set force is ap lied to the same and several other experimental conditions (temperature, frequency, or time) can be varied. Stress control is typically less expensive than strain co trol because only one shaft is needed, but this also makes it harder to use. Some adv ntages of stress control include the f ct that the structure of the sample is less likely to be destroyed and longer relaxati n times/ longer creep studies can be done with much more ease. Characterizing low iscous materials come at a disadvantage of short time responses that are limited by i ertia. Stress and strain control analyzers give about the same results as long as characterization is within the linear region of the poly er in question. However, stress contr l lends a more realistic response because polyme s have a tendency to resist a load.
Stress and strain can be applied via torsional or axial analyzers. Torsional analyzers are mainly used for liquids or melts but can also be implemented for some solid samples since the force is applied in a twisting motion. The instrument can do creeprecovery, stress-relaxation, and stress-strain experiments. Axial analyzers are used for solid or semisolid materials. It can do flexure, tensile, and compression testing (even shear and liquid specimens if desired). These analyzers can test higher modulus materials than torsional analyzers. The instrument can do thermomechanical analysis(TMA) studies in addition to the experiments that torsional analyzers can do. Figure shows the general difference between the two applications of stress and strain. Changing sample geometry and fixtures can make stress and strain analyzers virtually indifferent of one another except at the extreme ends of sample phases, i.e. really fluid or rigid materials. Common geometries and fixtures for axial analyzers include threepoint and four-point bending, dual and single cantilever, parallel plate and variants, bulk, extension/tensile, and shear plates and sandwiches. Geometries and fixtures for torsional analyzers consist of parallel plates, cone-and-plate, couette, and torsional beam and braid. In order to utilize DMA to characterize materials, the fact that small dimensional changes can also lead to large inaccuracies in certain tests needs to be addressed. Inertia and shear heating can affect the results of either forced or free resonance analyzers, especially in fluid samples.
NVH analysis
NVH is an industry term that stands for noise, vibration, and harshness. It is a search for the source of a noise, shake, or vibration, and it refers to the entire range of vibration perception, from hearing to feeling.
Noise is unwanted sound; vibration is the oscillation that is typically felt rather than heard. Harshness is generally used to describe the severity and discomfort associated with unwanted sound and/or vibration, especially from short duration events. NVH is also called sound quality analysis, which involves metrics such as loudness, sharpness, sound exposure level, and others. NVH Test Equipment Include
Analyzers, shakers and controllers, accelerometers, noise dosimeters, octave band filters, transducers for vibration and acoustics, dynamometers, sound level meters, microphones, and analysis software.
