Wiseco is unique because we forge all of our own pistons in house, and produce all of our own forge tooling right here in the USA.
The terms used here to define material properties and processing are explained immediately below. It is expressed as the applied load divided by the area to which the load is applied. Note that this is the simplest form of stress, to illustrate the point. It does not take into account bending, shear, torsion, or any other complexities.
The Ultimate Tensile Stress UTS of a given material is the stress value required to fracture the specimen pull it apart into two pieces.
The UTS and YS values are measured on a testing apparatus designed to gradually increase the load on a specimen until it fails, and measure the deflection as the load is applied. Figures 1 and 2 show such a test before and after fracture.
Figure 1 Figure 2 Tensile Test, Post-fracture Creep Fatigue life of piston the phenomenon in which a metal, when exposed to a high stress level over an extended time period typically hundreds or even thousands of hours will exhibit a quasi-permanent strain deformationwhich occurs at different rates depending on the length of exposure.
High temperatures generally increase the rate of creep. Fatigue is the term used to describe the breakage of a metal part that occurs when the part is subjected to a load which varies over time, even though the varying load is well below the YS of the material.
Fatigue is covered in detail on a dedicated page on this site. There are different types of fatigue loading. One is zero-to-max-to-zero, where a part carrying no load is subjected to a specific load, then the load is removed. An example is a chain used to pull logs behind a tractor.
Another type is a varying-load-superimposed-on-a-constant-load. The suspension wires in a bridge are an example of this type. The wires carry a constant static load from the weight of the bridge, plus an additional varying tensile load from the vehicles traveling across the bridge. The most severe case is the fully-reversing-load in which a specific tensile load is applied to the part then released, then a compressive load of the same value is applied and released.
An example is the load applied to the roots of the teeth in an idler gear. Fatigue tests use fully reversing loading to test the properties of materials, and the results are extremely statistical.
The number of cycles a given material can survive a specific fully-reversing stress increases as the stress level decreases.
Notch Toughness is a measurement of a material's resistance to breakage from impact loading. If you hit a diamond with a hammer, it will shatter; If you hit the head of another hammer with a hammer and the hammer in your hand will spring back; If you hit the fender of your car with a hammer, well you know how that turns out The pendulum is raised to a specific height and released.
It strikes the specimen right behind the notch and fractures it. The kinetic energy ft-lbs contained in the pendulum at the time it strikes the specimen is easily calculated. The energy remaining in the pendulum after it breaks the specimen can be calculated from the distance it travels post-fracture.
The energy required to break the specimen is obviously the difference between the two values, which is the CVN value ft-lbs for the material at the tested hardness. HRc - The hardness of a material as measured on the Rockwell "C" scale. There are several other hardness scales: HRc is the most frequently used scale for steels; HRb is a common measurement for softer metals.
Since the strength versus hardness relationship is known for each material, this test is a simple way to verify the strength of a known material. Work-Hardening is an increase in the strength and hardness of a metal resulting from plastic deformation at a temperature below the crystal-restructuring range.
Vacuum Induction Melting VIM is a primary-melt process for producing very high purity steels by melting the materials by induction heating inside a high-vacuum chamber.
Electro-Slag Remelting ESR is an open-air remelting process through a reactive slag which produces a clean steel with good crystallography.
Vacuum Arc Remelting VAR is a refining process in which steels are remelted inside a vacuum chamber to reduce the amount of dissolved gasses in the metal.
It is well established that material cleanliness absence of contaminants, oxides, bubbles, unwanted elements is a major contributor to high fatigue life. After the primary melt, there are various remelt processes which produce an increasing level of purity in the metal.
VIM-VAR is generally used to produce the cleanest and most expensiveof double-melt steel, nickel and titanium alloys, and therefore, the best fatigue properties of double-melt methods. Hot Isostatic Processing HIP is a method of essentially eliminating internal voids and microporosity in cast components and powder forgings.
The components are put in an autoclave and heated to a temperature appropriate for the material and held for several hours while being subjected to a high pressure atmosphere of inert gas as high as bar.
In a race engine environment, the demands can be extreme, calling for various combinations of high strength and high fatigue resistance at high temperatures, and the minimum weight which will meet the stress and life requirements.
The perfectly-designed race engine component would operate at its design level until just after the checkered flag of the last race it was designed to run.
The engineering challenge in material selection is complicated by the highly statistical nature of strength and fatigue ratings, as well as the practical problems of cost and availability.THIS IS AN EXPANDED VERSION OF AN ARTICLE BY Jack Kane WHICH APPEARED IN ISSUE of RACE ENGINE TECHNOLOGY MAGAZINE.
This page describes the important aspects of crankshaft design and implementation.
EATON Medium Duty Piston Motors -MOP-M September 3 General Overview Introduction Eaton Medium Duty Piston Motors convert hydraulic energy supplied by . stresses in various parts alongwith fatigue life of the piston has been attained which shows piston can work upto e6 no.
of cycles without any sign of failure. Keywords – Piston, Ansys, Fatigue. Fatigue Life Prediction of Two-Stroke Free Piston Engine Mounting Using Frequency Response Approach Therefore, it can reduce time to market, improve product reliability and customer. Fatigue Life Prediction of Two-Stroke Free Piston Engine Mounting Using Frequency Response Approach Therefore, it can reduce time to market, improve product reliability and customer.
Better fatigue life Excellent High Temperature Strength However, if wear is a consideration with either a or piston, JE offers an optional hard anodizing coating process for .