Walaupun masih harus kerja dan entar siang ada meeting ma Aqua, tapi hari ini pasti akan berlalu dengan cepat.

Mulai nge-list apa aja yang harus dibawa ke bandung karena selain mau pulang untuk ber-weekend-ria di sana, hari senin dan selasa juga ada kerjaan untuk ketemu calon customer.

Aah bosen nih,, belum ada kerjaan yang bikin mikir pake otak. masih mikir pake dengkul, hehehe. Pinter2 aja cari kerjaan lain selain bengong,, mau itu nge-blog, buka email, ym-an, buka pesbuk,  ber-google ria atau download2 e-book.

Untung ada meeting di luar kantor, sekalian buat jalan2 dan belajar hal yang baru. enaknya kerja di sini ya karena banyak kerjaan dan meeting di luarnya. apalagi sales, harus rajin2 keluar kantor buat nyari prospek. Asik juga ketemu orang2 baru dan ngobrol2 ma mereka, nemuin banyak culture baru dan ilmu untuk menghadapi karakter orang yg beda2. Seru!

Bakal betah gak ya kerja di sini? Hmm,, ampe saat ini sih masih betah2 aja. orang2nya baik, bersedia ngajarin banyak hal, dpt ilmu baru, cuman mungkin masalah salary aja gak sesuai ekspektasi. tapi yakinlah when they depend on me, the salary rise won’t become a problem (Tante Rani, 2009).

Hehehe, yang penting mah semangat aja lah ngejalanin dunia baru ini.

Dan weekend ini dinikmati di Bandung bareng orang2 tercinta,,

Bandung, I’m coming,,,!!!

Hardness is, however, used extensively to characterize materials and to determine if they are suitable for their intended use. All of the hardness tests described in this section involve the use of a specifically shaped indenter, significantly harder than the test sample, that is pressed into the surface of the sample using a specific force. Either the depth or size of the indent is measured to determine a hardness value.

Why Use a Hardness Test?

• Easy to perform
• Quick – 1 to 30 seconds
• Relatively inexpensive
• Non-destructive
• Finished parts can be tested – but not ruined
• Virtually any size and shape can be tested
• Practical QC device – incoming, outgoing

The most common uses for hardness tests is to verify the heat treatment of a part and to determine if a material has the properties necessary for its intended use. Establishing a correlation between the hardness result and the desired material property allows this, making hardness tests very useful in industrial and R&D applications.

Hardness Scales

There are five major hardness scales:

• Brinell – HB
• Knoop – HK
• Rockwell – HR
• Shore – HS
• Vickers – HV

Each of these scales involves the use of a specifically shaped diamond, carbide or hardened steel indenter pressed into the material with a known force using a defined test procedure. The hardness values are determined by measuring either the depth of indenter penetration or the size of the resultant indent. All of the scales are arranged so that the hardness values determined increase as the material gets harder. The hardness values are reported using the proper symbol, HR, HV, HK, etc. indicating the test scale performed.

Five Determining Factors

The following five factors can be used to determine the correct hardness test for your application.

• Material – grain size, metal, rubber, etc.
• Approximate Hardness – hardened steel, rubber, etc.
• Shape – thickness, size, etc.
• Heat Treatment – through or casehardened, annealed, etc.
• Production Requirements – sample or 100%

(source: http://www.instron.us/wa/applications/test_types/hardness/default.aspx)

Standards

Shore test methods are defined in the following standards:

• ASTM D-2240
• DIN 53 505
• ISO 7619 Part 1
• JIS K 6301*
• ASKER C-SRIS-0101

*Note: The JIS standard is very similar to the ASTM 2240 standard. However, there are small but important differences.

Shore Test Method

The Shore test uses a hardened indenter, an accurately calibrated spring, a depth indicator, and a flat presser foot. The indenter is mounted in the middle of the presser foot and extends 2.5mm from the surface of the foot. In the fully extended position the indicator displays zero. When the indenter is depressed flat even with the presser foot’s surface, the indicator displays 100. Therefore, every Shore point is equal to 0.0025mm penetration (M scale is 0.00125mm).

In use the unit is placed on the sample so that the presser foot is held firmly against the test surface. The spring pushes the indenter into the sample and the indicator indicates the depth of penetration. The deeper the indentation the softer the material and the lower the indicator reading.

The different Shore scales, A, B, C, D, DO, E, M, O, OO, OOO, OOO-S and R are created by using 7 different indenter shapes, 5 different springs, 2 different indenter extensions an 2 different presser foot specifications. The A and D scales are by far the most commonly used. The M scale uses a very low force spring and was developed to allow testing very small parts like O rings that can not be tested in the normal A scale. Because different materials respond to the test scales in different ways, there is no correlation between the different scales.

Applications

All Durometers except for the M scale units can be used as a portable device. Test stands are recommended for best accuracy and are required for M scale testing because of its increased sensitivity. Some stands have extra weights to make sure that the force on the presser foot is constant from test to test. Normally multiple tests are done on each sample and the average result is used.

Strengths

1. Fast, easy to use
2. Inexpensive
3. Wide range of materials can be tested
4. Non destructive, part can normally be used after testing

Weaknesses

1. Dwell time variables can cause poor readings.
2. Inconsistent force on the presser foot will cause errors.
3. Difficulties keeping the indenter perpendicular to the test surface will cause errors.
4. The test surface must be large enough to support the presser foot.

(source: www.instron.us/wa/applications/test_types/hardness/shore.aspx)

Why Perform a Flexure Test?

A flexure test produces tensile stress in the convex side of the specimen and compression stress in the concave side. This creates an area of shear stress along the midline. To ensure the primary failure comes from tensile or compression stress the shear stress must be minimized. This is done by controlling the span to depth ratio; the length of the outer span divided by the height (depth) of the specimen. For most materials S/d=16 is acceptable. Some materials require S/d=32 to 64 to keep the shear stress low enough.

Types of Flexure Tests

Flexure testing is often done on relatively flexible materials such as polymers, wood and composites. There are two test types; 3-point flex and 4-point flex. In a 3-point test the area of uniform stress is quite small and concentrated under the center loading point. In a 4-point test, the area of uniform stress exists between the inner span loading points (typically half the outer span length).

Typical Materials

• Polymers

The 3-point flexure test is the most common for polymers. Specimen deflection is usually measured by the crosshead position. Test results include flexural strength and flexural modulus.

• Wood and Composites

The 4-point flexure test is common for wood and composites. The 4-point test requires a deflectometer to accurately measure specimen deflection at the center of the support span. Test results include flexural strength and flexural modulus.

• Brittle Materials

When a 3-point flexure test is done on a brittle material like ceramic or concrete it is often called modulus of rupture (MOR). This test provides flex strength data only, not stiffness (modulus). The 4-point test can also be used on brittle materials. Alignment of the support and loading anvils is critical with brittle materials. The test fixture for these materials usually has self-aligning anvils.

Flexure Test Typical Configurations

Flexure Test Standards

ASTM

• D790-02 Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
• D6272-02 Standard Test Method for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials by Four-Point Bending
• C393-00 Standard Test Method for Flexural Properties of Sandwich Constructions
• C78-02 Standard Test Method for Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading)
• C293-02 Standard Test Method for Flexural Strength of Concrete (Using Simple Beam With Center-Point Loading)
• C1161-02b Standard Test Method for Flexural Strength of Advanced Ceramics at Ambient Temperature
• D143-94(2000)e1 Standard Test Methods for Small Clear Specimens of Timber
• D6109-97e1 Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastic Lumber
• D198-99 Standard Test Methods of Static Tests of Lumber in Structural Sizes
• C1341-00 Standard Test Method for Flexural Properties of Continuous Fiber-Reinforced Advanced Ceramic Composites
• D5572-95(1999) Standard Specification for Adhesives Used for Finger Joints in Nonstructural Lumber Products

ISO

• 178:2001 Plastics – Determination of Flexural Properties

(source: http://www.instron.us/wa/applications/test_types/flexure/default.aspx)

Why Do a Fatigue Test?

In many applications, materials are subjected to vibrating or oscillating forces. The behavior of materials under such load conditions differs from the behavior under a static load. Because the material is subjected to repeated load cycles (fatigue) in actual use, designers are faced with predicting fatigue life, which is defined as the total number of cycles to failure under specified loading conditions. Fatigue testing gives much better data to predict the in-service life of materials.

Typical Configuration

A servohydraulic fatigue testing machine is usually used to perform a fatigue test. This consists of a hydraulically operated actuator fitted into a high stiffness load frame to apply the load to the specimen. Because the system is hydraulically operated, it is possible to achieve both high loads and high cyclic frequencies.

The test system should be fitted with a control system that is capable of controlling the test and measuring data at high frequencies. It is also important that the load measurement system can accurately measure specimen load, and compensate for load errors induced by the dynamic movement of the test system.

Materials

Some typical materials that are subjected to fatigue testing:

• Metals
• Polymers
• Composites
• Elastomers
• Structural Components
• Ceramics

Standards

The following ASTM standards apply to fatigue testing:

• E1820
• E399
• E606
• E64

Test Types

• Low Cycle Fatigue

Low Cycle Fatigue (LCF) describes the service environment of many critical (and primarily metal) components: low frequency, large loads/strains. The LCF environment is typical of turbine blades (heat-up/cool down cycling) and other power generation equipment subject to thermal and/or mechanical cycling (ie. pressure vessels, piping, etc.) LCF typically involves large deformations, thereby accumulating damage on the specimen. LCF research is essential for the understanding of failure (in metals), for design and engineering purposes.

• High Cycle Fatigue

High Cycle Fatigue (HCF) results from vibratory stress cycles at frequencies which can reach thousands of cycles per second and can be induced from various mechanical sources. It is typical in aircraft gas turbine engines and has led to the premature failure of major engine components (fans, compressors, turbines). While LCF involves bulk plasticity where stress levels are usually above the yield strength of the material, HCF is predominantly elastic, and stress levels are below the yield strength of the material.

(source: http://www.instron.us/wa/applications/test_types/fatigue/default.aspx)

As indicated in the accompanying diagram, the creep of a material can be divided into three stages. First stage, or primary creep, starts at a rapid rate and slows with time. Second stage (secondary) creep has a relatively uniform rate. Third stage (tertiary) creep has an accelerating creep rate and terminates by failure of material at time for rupture.

How to Perform a Creep Test?

To determine creep properties, a material is subjected to prolonged constant tension or compression loading at constant elevated temperature. Deformation is recorded at specified time intervals and a creep vs. time diagram is plotted. Slope of curve at any point is creep rate. If failure occurs, it terminates the test and the time for rupture is recorded. If specimen does not fracture within the test period, creep recovery may be measured.

How to Determine Stress-Relaxation?

To determine stress-relaxation of a material, the specimen is deformed a given amount and decrease in stress is recorded over prolonged period of exposure at constant elevated temperature. The stress-relaxation rate is the slope of the curve at any point.

Typical Applications

• Metal Working
• Springs
• Soldered Joints
• High-Temperature Materials

(source: http://www.instron.us/wa/applications/test_types/creep_stress_relax.aspx)

Why Perform a Compression Test?

The ASM Handbook^®, Volume 8, Mechanical Testing and Evaluation states: “Axial compression testing is a useful procedure for measuring the plastic flow behavior and ductile fracture limits of a material. Measuring the plastic flow behavior requires frictionless (homogenous compression) test conditions, while measuring ductile fracture limits takes advantage of the barrel formation and controlled stress and strain conditions at the equator of the barreled surface when compression is carried out with friction. Axial compression testing is also useful for measurement of elastic and compressive fracture properties of brittle materials or low-ductility materials. In any case, the use of specimens having large L/D ratios should be avoided to prevent buckling and shearing modes of deformation¹.”

The image above shows variation of the strains during a compression test without friction (homogenous compression) and with progressively higher levels of friction and decreasing aspect ratio L/D (shown as h/d)¹.

Modes of Deformation in Compression Testing

The figure to the right illustrates the modes of deformation in compression testing. (a) Buckling, when L/D > 5. (b) Shearing, when L/D > 2.5. (c) Double barreling, when L/D > 2.0 and friction is present at the contact surfaces. (d) Barreling, when L/D < 2.0 and friction is present at the contact surfaces. (e) Homogenous compression, when L/D < 2.0 and no friction is present at the contact surfaces. (f) Compressive instability due to work-softening material¹.

Typical Materials

The following materials are typically subjected to a compression test.

• Concrete
• Metals
• Plastics
• Ceramics
• Composites
• Corrugated Cardboard

(source: http://www.instron.us/wa/applications/test_types/compression.aspx)

Bend testing measures the ductility of materials. Terms associated with bend testing apply to specific forms or types of materials. For example, materials specifications sometimes require that a specimen be bent to a specified inside diameter (ASTM A-360, steel products).

Bend testing provides a convenient method for characterizing the strength of the miniature components and specimens that are typical of those found in microelectronics applications. Instron^® has bend and flexure fixtures available for both three and four point loading.

(source: http://www.instron.us/wa/applications/test_types/bend_testing.aspx)

• Modulus of elasticity in shear
• Yield shear strength
• Ultimate shear strength
• Modulus of rupture in shear
• Ductility

While they are not the same, they are analogous to properties that can be determined during a tensile test. In fact, the “torque versus angle” diagram looks very similar to a “stress versus strain” curve that might be generated by a tensile test.

Why Perform a Torsion Test?

Many products and components are subjected to torsional forces during their operation. Products such as biomedical catheter tubing, switches, fasteners, and automotive steering columns are just a few devices subject to such torsional stresses. By testing these products in torsion, manufacturers are able to simulate real life service conditions, check product quality, verify designs, and ensure proper manufacturing techniques.

Types of Torsion Tests

Torsion tests can b e performed by applying only a rotational motion or by applying both axial (tension or compression) and torsional forces. Types of torsion testing vary from product to product but can usually be classified as failure, proof, or product operation testing.

• Torsion Only: Applying only torsional loads to the test specimen.
• Axial-Torsion: Applying both axial (tension or compression) and torsional forces to the test specimen.
• Failure Testing: Twisting the product, component, or specimen until failure. Failure can be classified as either a physical break or a kink/defect in the specimen.
• Proof Testing: Applying a torsional load and holding this torque load for a fixed amount of time.
• Operational Testing: Testing complete assemblies or products such as bottle caps, switches, dial pens, or steering columns to verify that the product performs as expected under torsion loads.

Typical Configuration

An electromechanical or hydraulically-powered testing machine can be used for torsion testing. An electromechanical drive system transfers the rotational motion of a motor to the specimen while a hydraulic system employs closed loop servo control together with a hydraulic power supply to apply torsion loads.

Both electromechanical and hydraulic systems should be fitted with a control system that is capable of controlling the test and collecting data at high frequencies.

(source: http://www.instron.us/wa/applications/test_types/torsion/default.aspx)

Honestly, it’s a new field for me. I’d studied a little bit about material while I was in college and I got C for this class. Now, I should deal with material tester and I must understand about test method and how to test any kind of material. I also must understand and memorize about the product and it’s accessories.

Well, because this is a new field for me, I will share what I’ve learned and my experiences to do my job.

First, I studied about material testing. There are bend test, flexure test, fatigue test, compressed test, creep and stress-relaxation test, impact test, shore test, hardness test, torsion test, and tensile test. I’ll explain it one-by-one in different posting.
So please please kindly review my other posting.