Mechanical Testing - Science topic

Dear all, better to follow ASTM procedures or any other standardized norms. Please have a look at the attached file. My Regards

The formula to calculate the circumferential tensile strength σc\sigma_cσc​ of a blood vessel is:

σc=^P⋅r/_t​

where:

This formula is based on the principle that the tensile strength is a function of the internal pressure, radius, and wall thickness.

Hello Ashrith Kumar Shetty

Thank you for your reply!

I will try it out and get back to you.

Please read the following introductory texts:

ISO 527/ASTM D638; ISO 178/ASTM D790; ISO 1183/ASTM D792 and

ISO 75/ASTM D648are the standards for Tensile Strength & Modulus; Flexural Strength & Modulus; Density and Heat Distortion Temperature respectively.

By computing the slope of the linear regression between σ30 and σ90, which correspond to 30 and 90% of the ultimate stress, one may derive Young's modulus from the stress-strain curves.

Utilising SEM and XCT, research on the alloy's deterioration SHOULD be conducted.

Fatigue simulation using FEA approach.

dynamic corrosion,

Hi Junxian Chen , from your experience is it chatGPT or Google Bard providing better replies to scientific questions?

Adjunto una imagen que podría ayudar a tu interrogante:

Dear Asep Bustanil Aripin

These are just a few examples of textbooks that cover analytical solutions in mechanics for plastic mechanical testing. You can also find many research papers and articles on this topic by searching academic databases like Google Scholar or Scopus.

Yes, there are several ASTM standards available for performing mechanical tensile tests on polymer nanocomposites. Some of the commonly used standards are:

The dimensions of the specimen depend on the specific ASTM standard chosen for the test. For example, ASTM D638 specifies the dimensions for Type I, II and III specimens. Similarly, ASTM D3039 and ASTM D882 specify the dimensions for different types of specimens.

Regarding the creation of a dog-bone mold using a 3D printer, there are several online resources available that provide files for 3D printing dog-bone molds. Some popular online resources include Thingiverse, GrabCAD, and MyMiniFactory. However, it is important to ensure that the dimensions of the mold are as per the ASTM standards to obtain accurate results.

Regarding the 3rd question, the area under curve represents toughness (amount of work done /unit volume) of material specimen, In you case it is 96.1kPa %. The tensile strength is however, ~580.1 kPa = ~ 0.6 MPa. and the Youngs (elastic) modulus is ~ (580.1 /95.5)*(100/1000) = 0.61MPa

However, i am not sure if there are direct conversion units from Pa% to J/mm^3 .

In the case of flexural strength and modulus of carbon fiber composites, the Rule of Mixture equation may not be the most accurate method for prediction. This is because carbon fibers have a much higher modulus of elasticity and strength than the polymer matrix, which can result in a non-linear behavior of the composite.

A more accurate model to predict the flexural properties of carbon fiber composites is the Mori-Tanaka model. This model takes into account the size and distribution of the fibers in the matrix, as well as the interface properties between the fibers and matrix.

Another model that can be used is the Hashin-Shtrikman upper and lower bounds. This model is based on the assumption that the composite is made of a mixture of two phases: a stiff phase and a weak phase.

Respected Madam

the following papers may be useful to you

1.

2.https://www.sciencedirect.com/topics/engineering/stress-relaxation-experiment

3. https://www.sciencedirect.com/topics/engineering/stress-relaxation-experiment

4. https://library.csbe-scgab.ca/docs/journal/29/29_2_209_raw.pdf

5. http://web.mit.edu/cortiz/www/Jerry/TPU_final.pdf

Hi,

Question still not clear? Could you elaborate more.

Himadri Nath Saha whats the difference between this method in the article and simple multiple force to displacement one by one?

Hello Mr.Michael William Spindler

I have a question how do you can calculate theta1 theta2 theta3 and theta 4 ?

I want to find constant Theta projection but I don't know how I can find constant.

Thanks

From your &inputph file, the value for nq1, nq2 and nq3 are for cubic and not for orthorhombic structure.

please I need the software for the TGA-50 instrument, Can you help me?

I have no experience, with this scenario, but suggest you start by defining the required performance envelope - maximum pressure, temperature range, (if variable), the aqueous/gaseous materials to be used, since those could impact whatever seal material, and the maximum planned individual test duration, in case seal life is limited by chemical interaction with the aqueous/gaseous environment. Then, review the test setup in Fig 1, at the link below, for suitability; it avoids moving part seals by using an expanding bellows type of chamber.

(Found via: https://duckduckgo.com/?t=ffab&q=high-pressure+mechanical%2Fcorrosion+test+systems+in+aqueous%2Fgaseous+environment+sealing&ia=web).

Dear Sudhir Kumar,

The R squared is not enough to verify your model. I think you should add a confirmation test and compare the results of obtained value with the model and experiment.

Strain is any kind of deformation, including elongation. Elongation is the word used if we're talking specifically about tensile strain which the sample deforms by stretching and becoming longer. Usually the percent elongation is calculated, which is just the length of the polymer sample after it is stretched (L), divided by the original length of the sample (L0), and then multiplied by 100.

Hello All,

Would it be correct to say the compressive strength of S275 steel is almost the same as the tensile yield? I'm looking for data and can't find a great deal

Also check https://www.sciencedirect.com/science/article/pii/S0260877413004329

Dear sir you can go for hand lay technique also

¿Alguien conoce cómo cambiar el nombre ?

ANSYS has the "Fatigue Tool", which is a very basic tool I would just recommend for very simple cases. nCode Design Life works well on the WB Platform. Maybe you can try that?

Waterjet cutting is suitable for almost any materials, including very fragile materials such as glass and ceramics.

Dear sir,

during my master degree my research work was on laser additive manufacturing.

i would like to pursue my doctor degree on additive manufacturing because of my previous work.

if there is any vacancy on additive manufacturing please let me know.

thank you

Ezekiel Yorke I believe you partly answered your question in the last sentence of the first paragraph-"for cost-effectiveness and resource-saving".

Dear Mr. Dilli R Dhakal

I come from reading your question, namely:

“I am trying to see the effect of modified GO on mechanical properties of CFRP composites. As a part of Mechanical testing, I am doing SENB test. In my understanding, SENB sample should have Notch followed by pre-crack. Can any one help me on creating the pre-crack on SENB sample of CFRP”,

published under the title

“How to make a pre-crack on Single-Edge Notched Beam (SENB) sample on Fiber reinforced polymer composite ?” on the ResearchGate platform.

Indeed, notching and pre-cracking are two facets of a problematic topic in Fracture Mechanics testing of polymeric materials. The literature published on the subject is extensive but the information and indications that can be drawn from it are far from being resolutive. The ESIS Technical Committee 4 (a group of experts from both academia and industrial laboratories, voluntarily engaged in the development of protocols and international standards for FM tests on polymeric materials) has been committed to this problem since the beginning of its activity (1985). Much experience has been accumulated and the task of defining a suitable crack starter will hopefully be reached soon: at present a new round-robin (interlaboratory) exercise is currently underway to validate a protocol covering all relevant details of a suitable notching technique for plain polymers. If the outcome of this exercise is positive, the protocol used will be proposed as an ‘addendum’ to ISO 13586:2018 “Plastics — Determination of fracture toughness (GIc and KIc) — Linear elastic fracture mechanics (LEFM) approach”, which is a revised version of the previous ISO 13586:2000, developed by the same ESIS TC4 group, in parallel with ASTM D5045–14.

But you are interested in testing CFRP. More specifically, since you are talking about SENB samples, I assume you mean plastics containing short fibers, not long or continuous fibers, which cannot be tested with SEN samples.

Well: you should know that in the case of short fiber reinforced plastics, the basic LEFM theory can only be applied with some reservations as the material homogeneity hypothesis is not fully verified. The case is dealt with in Annex B of ISO 13586:2018 (while it is not considered at all in ASTM D5045–14), and also in Annex C of ISO 17281:2018, which is an extension of the previous standard to the case of loading rate moderately high (1 m/s).

In particular, the issue of notching is dealt with in clause B.2.3 of Annex B of ISO 13586:2018.

I hope this information will be of help to you.

P.S.- A couple of notes on your question.

First, you write that you want “to see the effect of modified GO on mechanical properties ...” What do you mean by “modified GO”?

Second, in the title that precedes your question, you write “Single-Edge Notched Beam (SENB)”. Please note: B in the acronym SEN(B) stands for “Bend” or “Bending”, not for “Beam”, to distinguish it from SEN(T), where T stands for Tension, which is a possible variant.

@

Sincerely

Andrea Pavan

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Only with two extensometers mounted on the test piece (one longitudinal, the other transversal) one can measure the Posson's ratio. Only the people equipped to make true stress / true strain tests can do it (and they are not many). I strongly suggest to use cylindrical test pieces and to repeat the test many times, to have a sensible measurement. remember that all materials are anysotropic and this is valid also for Pisson's ratio.

In fatigue experiments the material and its microstructure plays a vital role. Its better you tell which material you are using and its composition. Also let me know whether you are using axial fatigue or rotating beam fatigue ,

Dear Johannes Luft,

Since magnesium alloy retains its strength and elongation after annealing at high temperatures , hence its high innovative demand in production technology. Mostly magnesium alloy fine wire is applicable in couple of potentials areas such as;

1. Surgical as Tension band wiring

2. Biodegradable applications, such as suture materials

3. Medical devices (bioabsorbable medical devices)

4. Cardiology; coil stents- potential applications for magnesium alloys in cardiovascular medicine

5. Orthopedic applications

6. Degradable implants with ligatures for blood vessels

7. Motor paddle shifters

8. High purity Magnesium Wire with the highest possible density for use in semiconductor etc.

Hope information is helpful for you.

Ashish

Thank you very much Moe Jmal. It will help full to us

In simple terms, the difference between those two conditions is whether or not the environment during testing is allowing the hydrogen to escape from the metal. After removal from a hydrogen environment, most metals will start to lose their hydrogen content, as the hydrogen atoms diffuse out of the material and recombine to escape as hydrogen gas. The rate of this loss depends on the material (particularly characteristics like diffusivity and solubility of hydrogen); a material like a ferritic steel may lose enough hydrogen content within the order of minutes that mechanical tests will no longer show an effect of hydrogen while an austenitic steel may take days to lose enough to no longer show an effect. Testing in a hydrogen environment removes (or at least reduces, depending on pressure) the driving force for the hydrogen to leave the sample.

So, which test conditions you want to use depends on the material being tested and the length of the test. If the hydrogen content loss in on the order of minutes, by the time the sample is removed from the environment, the test is set-up, and then run, it is unlikely that the results will show any effect of hydrogen. If the hydrogen content loss is on the order of days, then shorter tests (tensile, fracture toughness) can probably be run before losing too much hydrogen, but fatigue crack growth rate tests, which can take months, will show a decreasing effect of hydrogen as the test continues.

When the crack (be it planar or non-planar) is associated with crack-tip plasticity, the relations between the failure stresses in specimens tested in tension, compression and bending given above (see our answer 1) remain valid, except that σ_T is now multiplied by a quantity that contains the crack-tip plastic zone size, crack-front shape and orientation of average crack surface. Please see “NON-PLANAR CRACK WITH CRACK-FRONT PLASTIC YIELDING UNDER GENERAL LOADING” in our contributions in ResearchGate.

Yes, you can test. However, it is not a standard specimen size. Hence it is recommended to compare the tensile test result of a non-standard specimen with the standard test specimen. Also, you can report the results with the help of reference where they have employed these type of specimens.

Has anyone stored the digitize.opk for Origin V.75 and earlier. It is not available anymore on the fileexchange site. Thanks!

My friend, I suggest you use ABAQUS

The your sample can be measured nondestructively with shear gages and the shear modulus can be calculated from the measurements. A shear gage is a kind of strain gage that is used for testing rigid composite materials. And Poisson's ratio of samples like yours can be measured nondestructively with standard strain gages. As Mohammad Abboud has mentioned, stay in the elastic region of the material (no breaking or plastic deformation - only elastic bending)

In SEM it is possible to distinguish ductile zone and calculate the percentage.

weight acting capacity, stiffness, material, strength etc.

Slope gives the Young's modulus.

I recommend you to use a vacuum during preparation

I used a hex-saw once for the same. We can use milling machines if we have them around... Angle grinders can also be used for cutting the composites. If not we can also use a tiles cutting machine or Plywood cutting machines used in hard ware stores. Depending upon thickness one could also use a Rim cutter (paper cutting machine usually found in offices as a stationary)

Fibre composites provide an improved tensile strength due to delayed crack propagation and load transfer mechanism. Nonetheless, it has a very insignificant effect on the hardness.

I have followed the procedure described in the file attached for property determination and conducted the test as per described codes.

Dear Rana,

Both pin-on-disc and open tribometer are able to replicate the sliding velocities and contact pressures during cutting to some extent; however, open tribometer can simulate continuous sliding against freshly regenerated surface. The friction coefficient can be measured experimentally in dependence of the relative sliding velocity, contact pressure and temperature during machining with MQL.

The three machining conditions: (i) dry rubbing, representing the dry machining condition, (ii) MQL applied to front face rubbing which was similar to milling with MQL can be applied on the insert rake face and (iii) MQL applied to rear end rubbing which was similar to milling with MQL applied on flank face. Tribological tests can be carried out with coated tungsten carbide pins rubbing on CrMoV5 steel cylinder.

Ashish

Dear Mohsen,

You can check this book titled Concrete Technology by Neville and Brooks. Chapter 3 is for aggregate testings and chapters 6, 11, 12, 13, 14, 15, 16 are for concrete testings. The book can be downloaded here:

Good luck

The best procedure to prepare MXenes from MAX phase via:

1- HF

2- HF/H2SO4

3- HF/HCl

No. 1 is recomemnded. recommended

I will address the general solution divergence issue in Comsol. You can try following steps to improve the convergence.

Use structural meshes where you think you are getting the error (or use everywhere), Play with adaptive mesh refinement in solver or adapt option inside mesh node ~ Use this everytime to fine your meshes

Use the Generalized Alpha rather than BDF with strict or intermediate time stepping ~ this improves the convergence in many cases for me

Play with the tolerances (relative and absolute both) ~ sometimes if I change from factor to manual absolute tolerance (with enough time-discretization) it works.

Get the Jacobian update on every iteration than minimum ~ very important for non-linear solvers

Increase the number of maximum iterations ~ good option if you are using very fine tolerances

Change from fully coupled to segregated solvers ~ if you have many integrated physics

Use assembly in geometry and play with source to destination mesh refinements ~ when you are defining BCs or ICs inside the domains

Change scaled values of variables to manual and use values of their respective maximums ~ very helpful at the start of simulation fails.

Regards

Noman

Hello Manuel, I'm afraid you are missing the definition of pitting potential and breakdown potential. Sometimes they can be the same, as corrosion by pitting or by transpassive dissolution causes the breakdown of the passive film, localized or not. Pitting potential is usually much smaller than the actual breakdown potential due to the smaller potential required to the localized corrosion to initiate.

Maybe you can focus on the shape of the cavities.

Assume under uniaxial creep testing:

If the plastic hole growth takes control, then the cavities should be more like a standing needles which is perpendicular to the GB. Otherwise if the vacancy diffusion mechanism controls, the cavities should be like cracks that is parallel to the GB.

But to remember, when the constrained diffusional growth mechanism takes control, then the cavities growth rate actually depends on the slow creep deformation on the neighbourhoods matrix. However, the cavities look like the crack-type, since the vacancy diffusion contributes most of the growth but it is constrained by surrounding slow creep deformation rate. This is the most common type of creep cavitation.

Thanks Gordon and Anton for your valuable inputs.

I think both nano-indentation and ultrasonic wave instruments can help you to estimate the elastic modulus of spark plasma sintered ceramics.

ISO 2380-1:2004 specifies the shape/form, dimensions and designation of the tips of hand.

It also gives the technical specifications and test conditions for the screw-drivers and, in the case of hand-operated screwdrivers, specifies the test torque which the blade-to-handle connection shall withstand.

As bones are subjected to compression loads. so, compression test is very important for bone.Apart of it, fatigue test is also important because various dynamic loads also act on bone.

HI,

I think, from FEMFAT Material Data! It is a nice way to get input parmeters for ANSYS Strain Life calculation.

Best regards, László

If you need to know the 'type of deformation' you have to perform a full cycle in order to assesss if strains can be fully recovered (elastic or viscoelastic behaviour) or not (elasto-plastic or viscous behaviour).

Many indicators are constructed as functions of several variables not necessarily strongly correlated. The ultimate validity condition is their subject domain meaning. Frequently, they are used to measure a certain distance to an ideal modelling condition. Correlational methods, such as factor or principal components analyses, are very good exploratory techniques but they are restricted to linear relationships between the variables. So, you have a lot of work to do on your own.

I agree with Prof. Rethmeier. Our X-ray observation results show that the liquid metal may drop down through the gap in the butt welding, which will increase the penetration. Our following papers show the keyhole and molten pool in butt welding situation and bead-on-plate welding situation, respectively.

:(

Maybe blow some air through a stack of silica gel?

Or a few puffs from a can of 'dust off' spray?

If aluminium, silicone will stick quite well - so I'd start thinking about cutting a larger circular hole in the case, and gluing a sapphire disc to it. Then, make a hermetic seal with an impermeable blown polymer (even Armacel) and then the second disc glued to that. A sort of annular hamburger - with air space for the beef.

The article, "Evolution of Specimen Strain Rate in Split Hopkinson Bar Test," by H Shin and J-B Kim reports a method of validating the experimental result of the split Hopkinson bar. It cal also be used for the calibration of the instrument. The article can be downloaded at: https://doi.org/10.1177/0954406218813386

Have you tried other standards like ASTM D412, D790 or D695 ?

What about other methods for preparation of specimens like injection moulding?

As mentioned, for investigating contribution of each reinforcement, micro structural characterization near each interface must be examined. It can reveal about bonding of each contributing reinforcement and can be concluded to the strength provided by separate reinforcement according to bonding achieved and observed through in depth micro-structural analysis.

In the same field we can also do scratch test to see the surface morphology and reinforcing behavior according to the scratch trend near interface areas.

It all depends on your discussion. These types of contamination windows are the result of the electron beam polarising, attracting and cracking hydro-carbons on your specimens surface, effectively depositing carbon over the field of view. This gets the more problematic the higher your nominal magnification (smaller scan windows). If it's not a problem for your data interpretation then you can just state it. If your investigation is influenced by it then you need to either eliminate it (clean the surface) or control it reproducibly. A student of mine did a nice work on this topic a few years ago (see AJV Griffths and T Walther, J Phys Conf Ser 2010).

i think compressive strength is not to need but hardness must be calculated because polyvinyl alcohol may be make any chemical reaction, Hardness of materials is most affected it will be reduce material strength .....

General information like number of specimens, panel size etc are in standards (ie ASTM D7205 / D7205M). If you think about technology one of methods which I recommend is waterjet

Existence of upper and lower yield points is typical for alloyed steels. The reason for that is so called "solute drag", namely: solute atoms' preference to displace in the vicinity of the dislocations (due to an interaction of their stress fields with those of around dislocation core). Thus, when an external stress applied to a sample reaches the vicinity of a yield stress of the material, initially existing dislocations, surrounded (caught) by solute (impurity) atoms, need to additional stress to come off them. This "additional" stress developed onto the loaded sample, is seen as a "higher" yield point. When the majority of dislocations overcome their interaction to solute atoms, the yield point "fall" to its "lower" level. This mechanism works both for interstitial and substitutional solid solutions.

Regarding superalloys, their phase formation should be discussed in details for each specific case separately. For example, for multi-principle alloys (like high-entropy alloys), no "solute" atoms may be defined and then they normally do not demonstrate higher and lower yield points. For intermelallic hardened superalloys, the majority of alloying elements form inermetallide phases, so no "free"solute" atoms exist and then these materials also have no higher and lower yield points.

I am also working with strain gauges pasting it on circumference of the hollow circular pile. I am currently grooving the outside the layer of pile with the thickness of the gauge length of the strain gauges. The wires soldered to the strain gauges were sent from the holes made on the pile above the strain gauges and the strain gauges are then protected with the protective layer given by the HBM. Thus, driving the pile by hammering does not affect the strain gauges and the wires attached to it.

You can found it in the ASM Atlas of stress-strain curve, pages 523 foward.

If you don't find it, ask me.

Perhaps one should first define what one means by plastic instabilities. As long as we stick to tension, there is no confusion, because the manifestation of instability (necking) is both easily observed and well-defined mathematically.

On the other hand in a test like torsion, it is difficult to establish any geometric instability since the geometry is in principle invariant. Failure simply occurs when a certain condition is reached (consider for instance the max. shear stress criterion); do we consider this point as a plastic instability?

Going further to tests such as compression, where the geometry does change, but in a beneficial manner, making failure less likely. 'Instabilities' in this case would arise from the experimental setup, non-conservation factors like friction, and so on. These are very indirectly related to plasticity.

So at a macroscopic level, the definition is difficult.

At a microscopic level, we may observe certain manifestations; such as flow localisation. People have put forward instability criteria for such cases. These include empirical criteria (eg. Semiatin) as well as criteria developed on energy input/output considerations (eg. rate of energy storage to rate of energy dissipation).But the question again is, at what point do we call it an instability? Stage-I fatigue crack growth is governed by plasticity considerations and Stage-II is governed by fracture mechanics -which of these two is better described as a plastic instability? On one hand it should be Stage-I, because that is 'plastic', on the other hand Stage-II is a more evident 'instability'.

At room temperature, PCL is highly soluble in chloroform, dichloromethane, carbon tetrachloride, benzene, toluene, cyclohexanone and 2-nitropropane; slightly soluble in acetone, 2-butanone, ethyl acetate, dimethylformamide and acetonitrile; and insoluble in alcohols, petroleum ether, diethyl ether and water.

The reason for you getting the graphs that way is because while specifying the displacement boundary condition you chose an amplitude with a smooth curve. Smooth curve has zero velocity at the start and end as you can see in the displacement time graph. Your force time curve is a result of that

Dear all

There is a new work that tries to combine both the Hall-Petch and its inverse in one model through presenting a multiscale model that enables description of both the Hall-Petch relation and its inverse in one equation without the need of prior knowledge of the grain size distribution, for more details, please see the following link: