Concept explainers
The US Army helmet has evolved from sheet steel, to 29�layer Kevlar, to the current Kevlar/Twaron advanced combat helmet. The helmet liners have also changed from compressed paper fibers, plastic, and rayon to sophisticated suspension�webbing systems with chin straps. Exposure to brain�injuring shock waves from explosions is a current concern. A variety of materials and designs have been proposed for helmet liner systems, including: air� and fluid�filled (water or glycerin) chambers, layered composites with interfaces that reflect some of the incoming energy, foamed or cellular materials, aerogel, solid glass beads, hollow glass beads, and others. Select several of these and discuss the related pros and cons.
Want to see the full answer?
Check out a sample textbook solutionChapter 8 Solutions
DeGarmo's Materials and Processes in Manufacturing
Additional Engineering Textbook Solutions
Applied Statics and Strength of Materials (6th Edition)
Applied Fluid Mechanics (7th Edition)
Engineering Mechanics: Dynamics (14th Edition)
Introduction To Finite Element Analysis And Design
Fundamentals Of Thermodynamics
Engineering Mechanics: Statics & Dynamics (14th Edition)
- A ski is made up of:1. Top. Polyamide polymer that has a relatively low glass transition temperature and resists chipping.2. Torque box wrap. Composites reinforced with glass, aramid or carbon fibers. Various fabrics and reinforcing fillers are used to make possible the flex and decoration characteristics of a ski.3. Center. Foams, vertical wood laminates, foam and wood laminates, honeycomb structures and other materials. Commonly used woods include spruce, bamboo, balsa wood, and birch.4. Vibration absorption zone. Rubber is normally used.5. Basis. Ultra-high molecular weight polyethylene is used for its low coefficient of friction and resistance to abrasion.6. Borders. Heat treated carbon steel to 48 HRC hardness. It facilitates turning by "cutting" the snow.7. Layers of reinforcement. Fiber reinforced composites, usually fiberglass. Various fabrics and reinforcing loads to provide longitudinal stiffness. Describe the material, for example, define that it is a polyamide polymer.arrow_forwardA ski is made up of:1. Top. Polyamide polymer that has a relatively low glass transition temperature and resists chipping.2. Torque box wrap. Composites reinforced with glass, aramid or carbon fibers. Various fabrics and reinforcing fillers are used to make possible the flex and decoration characteristics of a ski.3. Center. Foams, vertical wood laminates, foam and wood laminates, honeycomb structures and other materials. Commonly used woods include spruce, bamboo, balsa wood, and birch.4. Vibration absorption zone. Rubber is normally used.5. Basis. Ultra-high molecular weight polyethylene is used for its low coefficient of friction and resistance to abrasion.6. Borders. Heat treated carbon steel to 48 HRC hardness. It facilitates turning by "cutting" the snow.7. Layers of reinforcement. Fiber reinforced composites, usually fiberglass. Various fabrics and reinforcing loads to provide longitudinal stiffness. Answer, what mechanical properties does each material have, add the definition…arrow_forwardProvide an sustanable and economical block flow diagram of rigid polyurethane foam from lignin.arrow_forward
- An extruder barrel has a diameter of 4.0 in and an L/D ratio of 28. The screw channel depth = 0.25 in, and its pitch is 4.8 in. It rotates at 60 rev/min. The viscosity of the polymer melt is 100 x 10-4 lb-sec/in2. What head pressure at exit is required to obtain a net volume flow rate of 150 in3/min? Assume that you are extruding 1/2 in PVC pipe (schedule 40) using the conditions above. How long would it take to extrude a 30 foot section? Be sure to note in your solution where you got your dimensions for the PVC pipe.arrow_forwardEAC in metals causes cracks to form and grow. What other feature can form and grow in amorphous polymers suffering from EAC?arrow_forwardViscosity is an important property of a polymer melt in plastics shaping processes. Upon what parameters does viscosity depend?arrow_forward
- Industrial Pipes Is the residual tightening given in screw cases intended to compensate for internal pressure and should be added to the initial tightening?arrow_forwardDifferentiate thermoplastics and thermosetting plastics with example materials .arrow_forwardSintering of ceramics may exhibit the following characteristics: Select one or more: a. The surface energy of the system increases b. It involves the high-pressure deformation of a pre-existing shape into a new form c. Pores become larger on average d. Pores become smaller e. Parts of the material may become amorphous f. The total surface area (including internal area) decreasesarrow_forward
- Types of post treatment for 3D printed plastics?arrow_forwardThese are some characteristics of composite materialsChoose an optionA) They are manufactured with the intention of preserving the individual properties of each of its components.B) The matrix is the phase that is found in greater proportion and houses the dispersed phase, which is responsible for resisting mechanical stresses.C) The structural can be formed by layers or sheets forming an isotropic material.D) The alignment of the fibers in a polymeric matrix does not affect the tensile or compressive strength.arrow_forwardHow does the use of additive manufacturing (3D printing) revolutionize the design and production of complex mechanical components, and what are the potential applications and challenges in implementing this technology across industries?arrow_forward
- Elements Of ElectromagneticsMechanical EngineeringISBN:9780190698614Author:Sadiku, Matthew N. O.Publisher:Oxford University PressMechanics of Materials (10th Edition)Mechanical EngineeringISBN:9780134319650Author:Russell C. HibbelerPublisher:PEARSONThermodynamics: An Engineering ApproachMechanical EngineeringISBN:9781259822674Author:Yunus A. Cengel Dr., Michael A. BolesPublisher:McGraw-Hill Education
- Control Systems EngineeringMechanical EngineeringISBN:9781118170519Author:Norman S. NisePublisher:WILEYMechanics of Materials (MindTap Course List)Mechanical EngineeringISBN:9781337093347Author:Barry J. Goodno, James M. GerePublisher:Cengage LearningEngineering Mechanics: StaticsMechanical EngineeringISBN:9781118807330Author:James L. Meriam, L. G. Kraige, J. N. BoltonPublisher:WILEY