fbpx
Connect with us

The Conversation

3D printing promises more efficient ways to make custom explosives and rocket propellants

Published

on

3D printing promises more efficient ways to make custom explosives and rocket propellants

3D printing can be used to build with all kinds of materials – even those that go ‘boom.’
kynny/iStock via Getty Images

Monique McClain, Purdue University

Imagine you’re driving to work on a rainy day, when a distracted, reckless driver hits your car out of nowhere. With a “boom,” an air bag deploys faster than you can blink your eyes to save your life.

That air bag deployed rapidly thanks to an energetic material called sodium azide, which generates nitrogen gas during a chemical reaction to inflate your airbag. But what’s an energetic material?

Energetic materials include propellants, pyrotechnics, fuels and explosives, and they’re used in all sorts of settings.

Uses of energetic materials include flares, matches, solid rocket boosters, gun propellants, hot thermite welding used to fuse materials together, fireworks and the explosive special effects in your favorite action .

Advertisement
A gold and white rocket, with flames coming out of its end, attached to a concrete scaffold.
Propellants rockets blast off.
U.S. Air Force/Joe Davila

Energetic materials in many shapes and sizes, but they’re often in a solid form and release a lot of energy through burning or exploding, depending on their shape and the conditions they’re operating in.

I’m a mechanical engineering professor who studies energetic materials. Making energetic materials isn’t easy, but developments in 3D printing could make customization easier, while allowing for more potential scientific applications.

The role of geometry

How energetic materials are made affects the shapes that they come in and how they release energy over time. For example, solid rocket propellants are made similar to a cake where a stand mixer stirs the “batter,” which is mostly made of ammonium perchlorate, aluminum and a rubbery binder, before it’s poured into a pan. The “cake” solidifies in the pan while it bakes in the oven.

Typically, rocket propellants have a cylindrical shape, but with a rod in the center. The rod often has a specific cross-sectional shape, like a circle or a star. When the propellant solidifies, the rod is , leaving the core shape behind.

The core shape affects how the propellant burns, which can affect the thrust of the motor it’s used in. Just by changing the central shape of the propellant, you can make a motor accelerate, slow down or maintain its speed over time.

Advertisement

But this traditional “cake baking” limits the shapes that you can make. You must be able to the rod after the propellant solidifies, so if the rod’s shape is too complex, you might break the propellant, which could make it burn erratically.

Designing propellant shapes that make rockets go faster or fly farther is an active area of research, but engineers need new manufacturing methods to create these increasingly complex designs.

3D printing to the rescue

3D printing has revolutionized manufacturing in a variety of ways, and researchers like me are to understand how it can improve the performance of energetic materials. 3D printing uses a printer to stack up material layer by layer to build an object.

3D printing allows you to make custom shapes, print multiple types of material in one part, and save money and material.

Advertisement
3D printing can be cost- and time-efficient.

However, it is very challenging to 3D-print energetic materials for several reasons. Some energetic materials are very viscous, which means it is very hard to squeeze that mixture out of a tube with a small nozzle. Imagine squeezing clay out of a small syringe – the material is too thick to easily move through the small hole.

In addition, energetic materials can be dangerous if handled improperly. They can ignite if there is too much heat during the manufacturing process or during storage, or if they are exposed to a static electric shock.

Recent progress

Despite this, researchers have made a lot of progress in the past decade to overcome some of these challenges. For example, scientists have 3D-printed reactive inks onto electronics to enable self-destruction if they fall into the wrong hands.

Scientists are studying how to print thin layers of thermite, a type of energetic material, onto surfaces.

Theoretically, you could also 3D-print these inks strategically onto old satellites or the aging International Space Station to break up these orbiting devices into small enough debris that burns up in the atmosphere before hitting the ground.

Advertisement

Many researchers are looking into 3D-printing gun propellants. Modifying the shape of gun propellants could make bullets that can fly farther.

Others have sought to use 3D printing to reduce the environmental impact of gun propellants and igniters that require harsh solvents to manufacture. These solvents are unsafe, difficult to dispose of and can harm the environment and peoples’ health.

I showed that it is possible to 3D-print solid rocket propellants that have similar properties to traditionally made propellants. With that research, we now have the to explore how propellants made of multiple materials burn, which is new territory.

To 3D-print rocket propellants, you first need to figure out how to print very viscous materials.

For example, instead of using a rod to made a cross-sectional shape in a propellant, you could 3D-print a highly reactive material that you could add to the center. Instead of having to remove that center material, you could burn it up so fast that it leaves a core shape behind. The reactive material would also add energy to the propellant. This would eliminate the need to use and remove a rod to make a central core.

Advertisement

While much of this research is in its infancy, companies such as X-Bow have been 3D-printing propellants and conducting successful flight tests with these motors.

Finally, several researchers have studied how 3D-printed explosives detonate. When the explosives are printed into a grid-shaped lattice, they react differently when their pores are filled with air or . This process produces a safer “switchable” explosive that does not react unless it is in a specific .

3D-printing energetic materials is still a new field. Scientists have a long way to go before we completely understand how 3D printing affects their safety and performance. But every day, scientists like me are finding new ways to use 3D-printed energetics to serve crucial, and sometimes lifesaving, purposes.The Conversation

Monique McClain, Assistant Professor of Mechanical Engineering, Purdue University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Advertisement

The Conversation

Why can’t it always be summer? It’s all about the Earth’s tilt

Published

on

theconversation.com – Stephanie Spera, Assistant Professor of Geography and the , University of Richmond – 2024-09-20 10:34:02

One hemisphere has summer, while the opposite has winter.

Prasit photo/Moment via Getty Images

Stephanie Spera, University of Richmond

Advertisement

Curious Kids is a for of all ages. If you have a question you’d like an expert to answer, send it to curiouskidsus@theconversation.com.


Why can’t it always be summer? – Amanda, age 5, Chile


With its long days just itching to be spent by doing nothing, summer really can be an enchanting season. As Jenny Han wrote in the young adult novel “The Summer I Turned Pretty”: “Everything good, everything magical happens between the months of June and August.”

But all good things must to an end, and summer cannot last forever. There’s both a simple reason and a more complicated one. The simple reason is that it can’t always be summer because the Earth is tilted. The more complicated answer requires some geometry.

I’m a professor of geography and the environment who has studied seasonal changes on the landscape. Here’s what seasons have to do with our planet’s position as it moves through the solar system.

Advertisement

This animation shows why the Earth has seasons.

Closeness to the Sun doesn’t explain seasons

First, you need to know that the Earth is a sphere – technically, an oblate spheroid. That means Earth has a round shape a little wider than it is tall.

Every year, Earth travels in its orbit to make one revolution around the Sun. The Earth’s orbit is an ellipse, which is more like an oval than a circle. So there are times when Earth is closer to the Sun and times when it’s farther away.

A lot of people assume this distance is why we have seasons. But these people would be wrong. In the United States, the Earth is 3 million miles closer to the Sun during winter than in the summer.

An artistic diagram shows the Earth revolving around the Sun.

Our distance from the Sun is not why we have seasons.

NASA

Advertisement

Spinning like a top

Now picture an imaginary line across Earth, right in the middle, at 0° latitude. This line is called the equator. If you drew it on a globe, the equator would pass through countries Brazil, Kenya, Indonesia and Ecuador.

Everything north of the equator, including the United States, is considered the Northern Hemisphere, and everything south of the equator is the Southern Hemisphere.

Now think of the Earth’s axis as another imaginary line that runs vertically through the middle of the Earth, going from the North Pole to the South Pole.

As it orbits, or revolves, around the Sun, the Earth also rotates. That means it spins on its axis, like a top. The Earth takes one full year to revolve around the Sun and takes 24 hours, or one day, to do one full rotation on its axis.

Advertisement

This axis is why we have day and night; during the day, we’re facing the Sun, and at night, we’re facing away.

But the Earth’s axis does not go directly up and down. Instead, its axis is always tilted at 23.5 degrees in the exact same direction, toward the North Star.

The Earth’s axis is tilted due to a giant object – perhaps an ancient planet – smashing into it billions of years ago. And it’s this tilt that causes seasons.

A series of diagrams showing the Earth's equator, axis and tilt.

Because of the tilt of the Earth, we are able to experience the seasons.

Stephanie Spera

Advertisement

It’s all about the tilt

So that means in June, the Northern Hemisphere is tilted toward the Sun. That tilt means more sunlight, more solar energy, longer days – all the things that make summer, well, summer.

At the same time, the Southern Hemisphere is tilted away from the Sun. So countries such as Australia, Chile and Argentina are experiencing winter then.

To say it another way: As the Earth moves around the Sun throughout the year, the parts of the Earth getting the most sunlight are always changing.

Fast-forward to December, and Earth is on the exact opposite side of its orbit as where it was in June. It’s the Southern Hemisphere’s turn to be tilted toward the Sun, which means its summer happens in December, January and February.

Advertisement

If Earth were not tilted at all, there would be no seasons. If it were tilted more than it is, there would be even more extreme seasons and drastic swings in temperature. Summers would be hotter and winters would be colder.

A diagram showing the Earth, its tilt and the Northern and Southern Hemispheres.

The Earth’s axis is always tilted at 23.5 degrees.

Stephanie Spera

Defining summer

to a meteorologist, climate scientist or author Jenny Han, and they’ll tell you that for those of us in the Northern Hemisphere, summer is June, July and August, the warmest months of the year.

But there’s another way to define summer. Talk to astronomers, and they’ll tell you the first day of summer is the summer solstice – the day of the year with the longest amount of daylight and shortest amount of darkness.

Advertisement

The summer solstice occurs every year sometime between June 20 and June 22. And every day after, until the winter solstice in December, the Northern Hemisphere receives a little less daylight.

Summer officially ends on the autumnal equinox, the fall day when everywhere on Earth has an equal amount of daylight and night. The autumnal equinox happens every year on either September 22 or 23.

But whether you view summer like Jenny Han or like an astronomer, one thing is certain: Either way, summer must come to an end. But the season and the magic it brings with it will be back before you know it.


Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the where you .

Advertisement

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.The Conversation

Stephanie Spera, Assistant Professor of Geography and the Environment, University of Richmond

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More

The post Why can’t it always be summer? It’s all about the Earth’s tilt appeared first on .com

Advertisement
Continue Reading

The Conversation

Men are carrying the brunt of the ‘loneliness epidemic’ amid potent societal pressures

Published

on

theconversation.com – Alvin , Associate Professor, Phyllis Northway Faculty Fellow, University of Wisconsin- – 2024-09-20 07:27:29

Singer Justin Bieber is seen on May 16, 2024, in Los Angeles.
BG046/Bauer-Griffin/GC Images

Alvin Thomas, University of Wisconsin-Madison and Quinn Kinzer, University of Wisconsin-Madison

A few weeks before Justin Bieber and his wife, Hailey, announced in May 2024 that they were expecting, the pop icon posted a selfie where he appears tearful and distraught.

While attention quickly pivoted to the pregnancy, there was little attention paid to the significance of a male celebrity and expectant father publicly sharing his vulnerability.

Advertisement

Yet Bieber’s social media post is notable for making his internal struggle visible.

Emotional pain is linked to serious health issues. But the public’s response to male expressions of emotion and vulnerability is often minimizing, if not dismissive. In response to Bieber’s tearful post, for example, Hailey described him as a “pretty crier.”

A year ago, the Canadian rapper Dax released the song “To Be a Man.” He said at the time: “This is a song I poured my heart into. I’m praying this reaches everyone who needs it.”

Today, the song’s message remains timely. It includes the lyrics:

Advertisement

Yeah, I know this life can really beat you down, uh
You wanna scream but you won’t make a sound, uh
Got so much weight that you’ve been holdin’
But won’t show any emotion, as a man, that goes unspoken

As researchers who study fatherhood and the roles that play in their families, we recognize the loneliness and pain in these lyrics. We have heard fathers describe the toll of attempting to keep a lid on their feelings.

In a recent study we conducted on 75 new and expectant Black fathers, they spoke of the need to address individual and collective trauma. This, they said, would ultimately help support their families. But they said resources to help men with their mental are often unavailable or very limited. They said they often feel invisible to health providers.

“Being a father and a man,” one participant said, “you have to keep the peace and be strong on the outside. But on the inside, you know, you’re falling apart.”

Advertisement

Dax’s lyrics and our research reflect an enduring social health challenge – the deafening silence that typically surrounds men’s mental health.

The toll of isolation on men

In May 2023, U.S. Surgeon General Dr. Vivek Murthy released an advisory highlighting what he described as an epidemic of loneliness and isolation in the country. Our research confirms this scourge.

Since men’s social support networks – colleagues, , close childhood friends – are often less robust than women’s, the epidemic disproportionately impacts men. The resulting solitude has very real health consequences.

Man walks alone along beach.
Studies show that loneliness is associated with negative health outcomes like elevated levels of heart disease and a higher risk of dementia.
Matthias Balk/picture alliance via Getty Images

In Murthy’s report, loneliness is associated with negative health outcomes, including a “29% increased risk of heart disease, a 32% increased risk of stroke, and a 50% increased risk of developing dementia for older adults. Additionally, lacking social connection increases risk of premature death by more than 60%.”

While Murthy’s report focuses on both men and women, research shows that men are less likely than women to seek mental health services. Additionally, men hold more negative attitudes toward seeking help, and they prematurely terminate treatment more often than women.

Advertisement

With these consequences in mind, a caring society may ask: Why are men carrying the brunt of this health risk, and what can be done about it?

Redefining men’s value beyond breadwinning

Many factors can contribute to feelings of isolation and disconnection among men.

In “To Be A Man,” Dax points toward one prominent factor:

As a man, we gotta pave our way
Our only function is to work and slave
There’s no respect for you if you ain’t paid
You’re disregarded as a human and you can’t complain

Advertisement

Traditional definitions of masculinity emphasize the importance of men’s role as breadwinners.

An uncertain economy and increasingly expensive housing and food prices make the ability to financially provide for a family elusive for many men. These factors also undermine men’s sense of self and contribute to loneliness and feelings of isolation.

As partners and fathers, men are still often perceived as deficient if they can’t provide economically. And societal norms stress that they are not valued for their capacity as caregivers, even if they are more involved in raising their than ever before.

This is out of touch with reality.

Advertisement

Men play an important role as caregivers in their children’s lives, according to our research, and exert a powerful influence on children’s health and well-being. Men also find meaning in their roles as fathers.

As Dax says:

As a man, our son is our horizon

The cost of suppressed vulnerability

Beyond pressures to provide, men also have to overcome enduring stereotypes that suggest they should be stoic and keep their fears and sadness to themselves.

Advertisement

Here, too, gender norms are in need of an . Boys and men need to feel comfortable presenting their true, authentic selves to the world. When they suppress their vulnerability, it creates a barrier to seeking help. It also perpetuates stigma and the epidemic of loneliness.

Man sitting in hospital room.
Men are less likely than women to seek mental health care.
Getty Images

There is a complex interplay between society’s assumptions and beliefs about men and fatherhood.

Men, consequently, are less likely than women to seek mental health services. Health providers, as a result, are more likely to underdiagnose and misdiagnose men. Additionally, when health resources are made available, they are often not tailored to men’s needs.

Societal expectations can create unbearable pressure for men. And the most marginalized groups, like low-income Black fathers, bear a disproportionate burden, research shows. This became more evident during the COVID-19 pandemic, when Black fathers working in high-risk and essential prioritized supporting their children and families over their own risk of infection and mental health.

As men continue to redefine their roles within families and communities, it’s important for society to create a space that acknowledges and embraces their vulnerabilities and full humanity in all social roles.

Advertisement

Men need outlets for their pain. They would benefit from relationships – with partners, family and friends – that support and nurture them in times of joy and through the emotional challenges. Their loneliness will continue to be disproportionate without the necessary connection to services.

Men can consider engaging in low-stakes discussion groups in their communities, with online groups and in their churches. They may also seek out therapists in person or online for introductory sessions to test out the therapeutic interaction before establishing a more consistent pattern of therapy services.

In “To Be a Man,” Dax sings:

No wonder most men are so depressed
All the things that they can’t express
It’s the circle of life, as a man, you provide
They don’t know what you’re worth ‘til the day that you die

Advertisement

As the Biebers adjust to life as parents, Justin may find people he can to about his experiences and emotions, people who see and value him fully. And we hope the same for every man and father, living their life out of the spotlight and doing the best they can for themselves and for their family.The Conversation

Alvin Thomas, Associate Professor, Phyllis Northway Faculty Fellow, University of Wisconsin-Madison and Quinn Kinzer, Graduate student and PhD Candidate, Department of Consumer Science, University of Wisconsin-Madison

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More

The post Men are carrying the brunt of the ‘loneliness epidemic’ amid potent societal pressures appeared first on theconversation.com

Advertisement
Continue Reading

The Conversation

Wind phones help the bereaved deal with death, loss and grief − a clinical social worker explains the vital role of the old-fashioned rotary phone

Published

on

theconversation.com – Taryn Lindhorst, Professor of Social Work, of Washington – 2024-09-20 07:26:00

The first wind phone was built in 2010 in Otsuchi, Japan.
Matthew Komatsu/Wikimedia Commons

Taryn Lindhorst, University of Washington

My mother died in my home in hospice in 2020, on the day my of Washington went into lockdown. Her body was taken away, but none of the usual touchstones for grief were available to our . There was no funeral or supportive gathering, no deliveries of food and no hugs. For months afterward, as the nationwide lockdown continued, thousands of other families like mine saw these rituals – society’s social supports for grieving – stripped away.

As a clinical social worker and health scholar with 40 years of experience in end-of-life care and bereavement, I knew that I needed some way to tend to my grief for my mother. While in lockdown, I began looking for resources to me. Then I heard about the wind phone.

Advertisement
One of the wind phones is in Olympia, Washington.

What is a wind phone?

At its simplest, a wind phone is a rotary or push-button phone located in a secluded spot in nature, usually within a booth-type structure and often next to a chair or bench. The phone line is disconnected.

People use the wind phone to “call” and have a one-way conversation with deceased loved ones. Here they can say the things left unsaid. Wind phones offer a setting for the person to tell the story of their grief, to reminiscence and to continue to connect to the person who is gone. For many, it is a deeply moving, life-affirming experience.

About 200 wind phones are scattered throughout the United States. Wind phones are open to the public, free of charge and usually found in parks, along walking trails and on church grounds. Typically, they are built by those who want to honor a lost loved one.

The wind phone began in Japan in 2010, when Itaru Sasaki, a garden designer, built a phone booth in his yard so he could “talk” with a deceased relative. Months later, the Fukushima earthquake and tsunami hit; in a matter of minutes, more than 20,000 people died.

Advertisement

Sasaki opened the phone booth to his neighbors, who urgently needed a place to express their grief. Word spread, and soon people came on pilgrimage from around Japan to speak through the “phone of the wind” to those they loved.

Since then, wind phones have spread throughout the world.

The story of the first wind phone.

Do wind phones work?

Grief is a universal human experience; it affects us psychologically, socially, spiritually and even biologically. Some of our first rituals as humans are those surrounding death, with some practices more than 10,000 years old, such as using flowers in burial ceremonies and positioning the deceased as if asleep, with a pillow under their head.

Yet there is still no clear guidance on how people should deal with grief. But the power of speaking to rather than about the deceased has long been at the root of many grief interventions worldwide, including Gestalt therapy, which encourages to role play or reenact life experiences. A common approach taken by a Gestalt therapist is letting the client speak directly to an empty chair while imagining the person they’ve lost is sitting there. A similar approach is to write a letter to the deceased and then read it out loud.

Advertisement

What these techniques and the wind phone have in common is the use of a conversational approach that allows connection, reflection and the safe release of strong emotions. By their very nature, both speaking and writing encourage direct emotional expression; this helps release physical and psychological tension in the body.

What’s more, the spontaneity of saying it out loud can reveal subconscious insights. That’s because talking can outpace internal censorship of painful .

Using a wind phone can elicit strong feelings, and not all are positive ones. They may elicit tears, anger, guilt and shame. Some conversations become confessional. The wind phone setting provides a way to contain feelings that the bereaved worry might overwhelm them.

Research is needed

In American culture, it’s common to talk about obtaining closure for the loss of a loved one – to get over it and move on. It is true that the initial period of deep sadness and trauma typically fades over time, but some grief can persist across a lifetime. In the weeks, months and years after the death, feelings can erupt unexpectedly in “grief attacks,” or as sudden waves of emotion, triggered by a memory, a smell, an event or a thought.

Advertisement

To my knowledge, no research has been conducted on wind phones, so it’s not yet possible to say from a scientific perspective whether they definitively help a person cope with their grief. This is not surprising; studies on grief have not received as much research attention as mental disorders, such as depression or anxiety, although grief can lead to either of these disorders.

Yet the rapid spread of wind phones over the past decade suggests, if nothing else, that there is an almost universal need for those in mourning to engage with grief. And for the thousands who have tried it, there is comfort to be found through a one-way call.The Conversation

Taryn Lindhorst, Professor of Social Work, University of Washington

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More

Advertisement

The post Wind phones help the bereaved deal with death, loss and grief − a clinical social worker explains the vital role of the old-fashioned rotary phone appeared first on .com

Continue Reading

Trending